Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
1998-03-05
2001-01-30
Sanghavi, Hemang (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
C385S053000, C385S055000, C385S072000
Reexamination Certificate
active
06179478
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a sleeve for connecting between ferrules to hold, for example, an optical fiber.
Conventionally, split sleeves as shown in
FIG. 4
have generally being used to photo-couple to one another to each other, in a simple manner, ferrules for holding an optical fiber. As shown in
FIG. 4
, the conventional split sleeve
100
is formed with one strip of a penetrating groove
102
in an axial direction of the cylindrical member
101
, which is made of ceramics such as zirconia and usually formed by sintering a cylindrical member, then lapping an inner surface, and then forming a slit by grinding. There has also been used a split sleeve
200
as shown in
FIG. 5
that has a plurality of axially-extending concave portions
202
that are spaced at such an interval as to be in parallel with each other on an inner peripheral surface
201
a
of the cylindrical member
201
to have one strip penetrating groove
203
formed in the axial direction.
With the shape having the one strip penetrating groove provided in the cylindrical member as shown in
FIG. 4
, however, the inner peripheral surface is usually formed in a surface without roughening. Accordingly, it becomes difficult to maintain the position in which the ferrule is held constant, and the inner diameter dimension tends to deviate. Therefore, there is a problem that the center of the ferrule may somewhat deviate thereby degrading alignment stability. For example, when the sleeve is used to connect ferrules holding an optical fiber, the coupling loss becomes large. Also, the split sleeve as described above tends to be affected by dusts or ground powders, raising a problem of instability in withdrawal force/coupling loss.
Under such circumstances, a split sleeve as shown in
FIG. 5
has been used which has the concave portions
202
provided on the inner peripheral surface of the cylindrical member. However, the split sleeve shown in
FIG. 5
has to hold a ferrule in a line so that there are disadvantages of high friction and dust occurence. Also, the contact surface between the ferrule and the cylindrical member is small so that the ferrule tends to be removed off, thus keeping the coupling state insufficient.
The present invention has been made to overcome the foregoing drawbacks in the conventional art. It is the object of the present invention to provide a sleeve which is excellent in alignment stability and capable of positively supporting a ferrule with less dust occurrence. Another object of the present invention is to provide a manufacturing method for the sleeve.
SUMMARY OF THE INVENTION
A first form of the present invention lies in a sleeve adapted for fitting rod members therein from respective sides to thereby place the rod members at their tip surfaces in abutment against each other, characterized in that: the sleeve is generally in a cylindrical form to have at least three convex projections or strips provided on an inner peripheral surface that continuously and helically extend at an equal interval from one end to the other end of the sleeve.
This can increase the holding force in a ferrule-withdrawal direction to thereby improve alignment stability.
Here, the sleeve may have at least one strip of an axially extending penetrating groove.
A second form of the present invention lies in a sleeve adapted for fitting rod members therein from respective sides to thereby place the rod members at their tip surfaces in abutment against each other, characterized in that: the sleeve is generally in a cylindrical form to have at least three convex strips provided in an inner peripheral surface that project in a direction inclined from a radial direction to a predetermined circumferential direction so as to extend continuously and at an equal interval from one end to the other end of the sleeve.
This enables the convex strip to be elastically deformable by a slight amount in a radial direction so that the ferrule can be given with an urging force and positively held due to the radial elastic deformation.
Here, the convex strip may be provided to helically extend between the ends of the sleeve.
Also, the sleeve may have at least one strip of a penetrating groove extending in an axial direction.
REFERENCES:
patent: 4134641 (1979-01-01), Kao et al.
patent: 4193665 (1980-03-01), Arnold
patent: 5239603 (1993-08-01), Sonoda et al.
patent: 196 29 510 (1997-01-01), None
patent: 185413A1 (1986-06-01), None
patent: 543094A1 (1993-05-01), None
Patent Abstracts of Japan, vol. 013, No. 215 (P-874) May 19, 1989.
Patent Abstracts of Japan, vol. 008, No. 141 (P-283) Jun. 30, 1984.
Shouji Setsuo
Tsunemi Masahiko
Adams & Wilks
Cushwa Benjamin
Sanghavi Hemang
Seiko Instruments Inc.
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