Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
1999-12-06
2001-09-04
Chang, Audrey (Department: 2872)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S062000, C385S078000, C385S060000
Reexamination Certificate
active
06283643
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ferule into which an optical fiber is inserted which has a core covered with one or plural protecting films and not covered with its end, and a method of processing the end of the optical fiber.
2. Description of the Related Art
In a prior art, where optical fibers are connected to each other and a light emitting/receiving element is connected to an optical fiber, a ferule was securely attached to the end of the optical fiber.
Now referring to
FIG. 16
, an more detailed explanation will be given of the prior art.
FIG. 16
is a sectional view of the attachment state between an optical fiber and a ferule, which is disclosed in JP-A-9-90163.
As seen from
FIG. 16
, a ferule, generally
1
is composed of an inner small-diameter cylinder
2
and an outer outer-diameter cylinder
3
, which are stepped. The outer cylinder
3
is provided with a flange
4
on its outer wall. The flange
4
is adapted to receive urging force of a spring (not shown) mounted in an optical connector housing (not shown).
An optical fiber
5
has a core
6
covered with two sheathing films, an inner primary sheath
7
and an outer secondary sheath
8
.
The small diameter cylinder
2
has an inner diameter that is slightly larger than the diameter of the core
6
of the optical fiber
5
. The larger diameter cylinder
2
has also an inner diameter that is slightly larger than the outer diameter of the secondary sheath
8
.
As seen from
FIG. 16
, the optical fiber
5
has an end which is covered with no sheathing film. The optical fiber
5
, with an adhesive (two-liquid mixed epoxy resin adhesive in the above prior art) being applied to the outer surface of the optical fiber inclusive of the end, is inserted in the ferule
1
. In this state, when the structure thus formed is heated for a prescribed time at a prescribed temperature, the optical fiber
5
and ferule
1
are coupled with each other with sufficient adhesive force.
The two-liquid mixed epoxy adhesive used in the prior art can provide great adhesive force. However, use of this adhesive requires a large number of working steps for processing or trimming for the end of the optical fiber
5
, i.e. application of an adhesive, insertion of the optical fiber, wiping off of the excessive amount of adhesive, heating/hardening of the adhesive, etc. This influences the production cost.
Changes in the mixing ratio of the two adhesive liquids will vary the adhesive intensity. This will make the quality control complicate.
Further, heating/hardening of the adhesive which satisfies the condition of e.g. 100° C. and one hour requires a comparatively large heating device. Therefore, a sufficient working space must be assured. A limited working space cannot increase the number of times of heating/hardening, which leads to reduction in the productivity.
SUMMARY OF THE INVENTION
A first object of the present invention is to a ferule capable of making it easy to process or trim the end of an optical fiber to reduce the production cost and improve quality control and productivity.
A second object of the present invention is to provide a method for processing the end of the optical fiber.
A third object of the present invention is to provide an assembly of an optical fiber and a ferule which can be surely coupled with each other.
In order to attain the first object, in accordance with the present invention, there is provided a ferule for receiving a ferule composed of a core and a sheathing for covering the core exclusive of its end, comprising
a core holder for holding the core;
a sheath holder for holding the sheathing, the sheath holder communicating with the core holder and being located on an outer wall of the sheathing; and
a metallic cylinder member for fixing the sheathing, the metallic cylinder member being formed integrally to the sheath holder, wherein the sheathing holder has a window from which the metallic cylinder member is partially exposed; and the metallic cylinder member is caulked through the window so that the sheathing is compressed toward the core.
In this configuration, the optical fiber and ferule can be surely secured to each other without using any adhesive.
Specifically, with the optical fiber whose end is void of the sheathing being inserted into the ferule, the metallic cylinder member can be caulked to compress the sheathing toward the core. Thus, the above securing or fixing can be completed. The fixing force can be easily altered by changing the position and area subjected to caulking. Even if external force is applied to the optical fiber, the edge of the metallic cylinder member is caught by the sheathing. Thus, the fixing force between the ferule and the optical fiber is not reduced and the optical fiber will not be readily fallen off.
Since the metallic cylinder member is exposed through the window, caulking can be easily positioned. Thus, the caulking position is not shifted so that the operation of caulking can be stabilized every time, thereby keeping the fixing force constant.
The ferule, which can be previously manufactured by a separate process, does not exert an influence on the operation of fixing to the optical fiber. Since a large space is not required for the caulking, a change in the layout of a manufacturing location is not required.
Preferably, in the ferule, the window is located centrally in the sheathing holder in its longitudinal direction. For this reason, the caulking position can be made unaltered. Additionally, if the shape of the assembly after caulking is unaltered, when the assembly is mounted in an optical connector housing, a play or clearance of the ferule for the optical connector housing is also unaltered. This makes it easy to design the optical connector using the optical connector housing.
In the ferule, preferably, the metallic cylinder member is located internally of the outer wall of the sheath holder. Therefore, the metallic cylinder will not protrude from the sheathing holder. This makes it easy to set the assembly in a jig in a step after the caulking or to mount the assembly in an optical connector housing. Further, using a level difference formed between the outer wall of the sheathing holder and the metallic cylinder member for caulking, the assembly can be engaged with an engagement member of the optical connector housing. This prevent the assembly from being fallen from the optical connector housing.
Further, in the ferule, preferably, the sheath holder has an internal taper with which the sheath is brought into contact. This enhances the degree of fitness between the ferule and the optical fiber after assembled.
Further, in the ferule, preferably, the core and the core holder are aligned with each other in their end faces.
This configuration prevents random reflection of light at the end face of the core and reduces optical loss there.
Further, in the ferule, preferably, the core holder is made of synthetic resin. For this reason, when the optical fiber is mounted in the optical connector housing, or is received by a receptacle, the optical connector housing or receptacle will not be injured.
In order to attain the above second object, in accordance with the present invention, there is provided a method of processing and end of an optical fiber using the ferule according to the present invention, comprising the steps of:
inserting the optical fiber into the ferule until the core of the optical fiber protrudes from the core holder;
caulking the metallic cylindrical member so that the optical fiber and the ferule are fixed to each other; and
cutting or grinding a portion of the core protruding from the core holder so that the core and the core holder are aligned with each other in their end faces.
In this process, since adhesive is not required to fix the ferule and optical fiber to each other, the end face of the optical fiber can be easily processed or trimmed. Specifically, when the ferule and optical fiber are fixed to each other using the adhesive, it takes a long time since the adhesive must be
Armstrong Westerman Hattori McLeland & Naughton LLP
Boutsikaris Leo
Chang Audrey
Yazaki -Corporation
LandOfFree
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