Electrolysis: processes – compositions used therein – and methods – Electroforming or composition therefor – Roll – ring – or hollow body
Reexamination Certificate
1999-11-26
2002-07-16
Bell, Bruce F. (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electroforming or composition therefor
Roll, ring, or hollow body
C205S050000, C205S078000, C205S079000, C385S060000, C385S078000
Reexamination Certificate
active
06419810
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to an optical fiber connector, a ferrule to be used for the optical fiber connector, and a method for producing the ferrule. In particular, the present invention relates to an optical fiber connector for correctly aligning mutual positions of cores of optical fibers and connecting them to one another by inserting the optical fibers into cylindrical ferrules to support them, a ferrule to be used for the optical fiber connector, and a method for producing the ferrule. The present invention also relates to a wire member-supporting apparatus to be used for producing the ferrule.
2. Description of the Related Art
In recent years, the electric cable for the telephone line is being replaced with the optical fiber cable on a worldwide scale. The use of the optical fiber is not limited to the optical communication based on the telephone. The optical fiber is also widely used for optical devices, apparatuses for LAN, and a variety of optical systems. Methods are known to mutually connect optical fibers in such an optical communication system, including a permanent connection method based on the use of fusion or mechanical splice, and a detachable connection method based on the use of an optical fiber connector. It is required for the optical fiber connector used for the latter method that attachment and detachment can be easily performed, and the optical fiber connector is resistant to the environment. Additionally, in order to respond to the demand for the optical communication system to realize long distance communication and large capacity, for example, it is required for the optical fiber connector that the connection loss is low, and the nonreflective treatment is applied in order to stabilize laser transmission.
Conventionally, as shown in (C) of
FIG. 1
, an optical fiber connector comprises tubular parts (hereinafter referred to as “ferrules”)
1
a
,
1
b
having a perfect circular cross section for highly accurately holding optical fibers
40
a
,
40
b
having a diameter of about 0.13 mm at predetermined positions and fixing them coaxially, and an aligning section
42
for holding the ferrules
1
a
,
1
b
while allowing them to make mutual abutment. For example, the ferrule has a columnar configuration as shown in (A) of
FIG. 1
, and it is made of a zirconia ceramic material or the like. The ferrule
1
shown in (A) of
FIG. 1
is a ferrule of the one-core type. For example, the ferrule
1
has a perfect circular through-hole
2
of &phgr;=0.126 mm which is formed in the longitudinal direction at the center of the column having a length of about 8 mm. A ferrule
1
′ shown in (B) of
FIG. 1
is a ferrule of the two-core type. The ferrule
1
′ is bored with two through-holes
2
a
,
2
b
for allowing two optical fibers to pass therethrough.
When the ferrule as shown in (A) of
FIG. 1
is produced, the following method has been hitherto adopted. At first, a mixture of zirconia powder and resin is used as a raw material which is molded to have a cylindrical configuration by employing, for example, a mold for injection molding or extrusion molding to mold the cylindrical configuration. Subsequently, a molded product is fired at a temperature of about 500° C. to decompose the resin component, followed by being fired at a high temperature of about 1200° C. An obtained cylindrical fired product has a through-hole into which a diamond-polishing member having a liner configuration is inserted so that the inner diameter of the through-hole is finely adjusted. Finally, the outer portion of the cylindrical product is machined about the center of the inner hole to finish the ferrule so that it has a perfect circular shape.
In the molding method described above, the fired molded product is slightly contracted due to the firing, and the inner diameter thereof is deviated from a desired dimension. For this reason, the polishing process based on the use of the diamond-polishing member, which is performed after the firing, is a necessary and indispensable treatment. However, the polishing process is laborious, and it requires skill, causing the decrease in productivity. Further, it has been not easy to obtain a perfectly uniform inner diameter concerning the position in the axial direction of the inner hole of the fired product even when the polishing process is performed, for example, because the diamond is not uniformly attached to the linear polishing member. Further, a problem arises in that the equipment cost is expensive, because the diamond-polishing member is consumed and exhausted.
A molding machine and a mold, which are expensive and specialized in this purpose, are required to perform the injection molding or the extrusion molding as described above. Especially, the molding machine and the mold are conspicuously abraded by the extremely hard zirconia powder, and hence their service lives are short as well. It is also possible to use a hard material for the surfaces of the molding machine and the mold. However, the production cost is extremely expensive for such a special molding machine and a special mold. Further, the energy cost is increased, and the energy source is wasted as well, because the firing is performed at a high temperature of 500 to 1200° C. in the firing step. If the production cost of the ferrule is increased as described above, the production cost of an optical fiber connector including the ferrule accommodated therein is also increased.
Further, the following problem also arises. Although the ferrule of the one-core type as shown in (A) of
FIG. 1
has been hitherto dominantly used, the ferrule of the two-core type as shown in (B) of
FIG. 1
or ferrules having more than two cores are gradually demanded. In the case of the ferrules having two or more cores, it is extremely difficult to perform the step to establish the dimension by means of the polishing with the diamond-polishing member. The production of ferrules having three or more cores has been substantially impossible.
When optical fibers are connected to one another by using an optical fiber connector, the process is executed by means of the connection in which tips of the optical fibers are allowed to make mutual abutment, i.e., so-called physical contact (hereinafter referred to as “PC”), in order to decrease the reflection loss at the connecting portion. In order to achieve the PC connection, the following processing has been performed. That is, the end surface of the ferrule is polished to have a convex spherical surface or an oblique convex spherical surface, or the end surface of the ferrule is polished to have a flat surface or an oblique flat surface, together with the tip of the optical fiber in a state in which the optical fiber is charged in the ferrule. The conventional ferrule made of zirconia or glass has involved the problem that such process cannot be easily performed.
In the conventional technique, when the ferrule is installed to the optical fiber connector, then the ferrule is installed in a holder, and it is installed to the optical fiber connector together with the holder, in order to adjust the rotational position of the ferrule. A problem has been also pointed out in that the number of parts of the optical fiber connector is increased due to the use of such a holder.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the problems involved in the conventional technique as described above, a first object of which is to provide a ferrule, a method for producing the same, and an apparatus for producing the same, wherein the ferrule can be produced at low energy cost with a simple and cheap equipment without any necessity for the expensive and special equipment such as a molding machine and a mold.
A second object of the present invention is to provide a ferrule, a method for producing the same, and an apparatus for producing the same, wherein the ferrule is excellent in dimensional stability, and it can be produced in accordance with a process with high product
Okamoto Shinichi
Tanaka Tetsuo
Bell Bruce F.
Nicolas Wesley A.
Nixon & Vanderhye P.C.
Tanaka Tetsuo
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