Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
1998-12-10
2001-07-10
Kim, Robert H. (Department: 2877)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S089000, C385S071000
Reexamination Certificate
active
06257770
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical connector and, more particularly, to a ferrule for an optical connector that connects optical fibers to each other.
FIG. 10A
shows a ferrule for an optical connector disclosed in Japanese Patent Laid-Open No. 62-276513 (Reference 1), and
FIG. 10A
shows this ferrule from which its upper and lower molds are removed.
As shown in
FIG. 10B
, a press plate
74
made of a silicon material is adhered to a silicon support plate
73
having an upper surface formed with V-shaped optical fiber guide grooves and guide pin grooves, thereby forming optical fiber guide holes
81
and guide pin holes
82
each having a regular-triangular cross section. Optical fibers
75
are inserted in the optical fiber guide holes
81
, and closed with upper and lower molds
72
and
71
, as shown in FIG.
10
A. Molding with a resin
76
is performed including the optical fibers
75
, thereby fixing the optical fibers
75
.
Japanese Patent Laid-Open No. 62-276514 (Reference 2) also discloses a technique similar to that of
FIGS. 10A and 10B
.
FIG. 11A
shows a ferrule for an optical connector disclosed in Japanese Patent Laid-Open No. 3-179406 (Reference 3), and
FIG. 11B
shows the main part of the same.
As shown in
FIG. 11A
, a ceramic support plate
90
having an upper surface formed with V-shaped optical fiber guide grooves and guide pin grooves is buried in a molded resin
93
. Optical fiber guide holes
91
and guide pin holes
92
each having a circular cross section are formed in the molded resin
93
with reference to these optical fiber guide grooves and guide pin grooves.
More specifically, the optical fiber guide holes
91
and guide pin holes
92
extend from the interior of the molded resin
93
and open in a side end face
94
of the molded resin
93
through the optical fiber guide grooves and guide pin grooves of the ceramic support plate
90
. As shown in
FIG. 11B
, the side end face
94
of the molded resin
93
is separate from a side surface
95
of the ceramic support plate
90
by a distance L.
Japanese Patent Laid-Open No. 3-179405 (Reference 4) also discloses a technique similar to that of
FIGS. 11A and 11B
.
In the prior art of
FIGS. 10A and 10B
or
FIGS. 11A and 11B
, the grooves are formed in the silicon support plate
73
or ceramic support plate
90
, and the optical fiber guide holes
81
or
91
and the guide pin holes
82
or
92
are formed at the predetermined portions of the silicon support plate
73
or ceramic support plate
90
.
In the prior art of
FIGS. 10A and 10B
, when optical connectors are to be connected to each other, the distal ends of the optical fibers
75
cannot be made to project by a small amount (e.g., 0.5 &mgr;m to 1 &mgr;m) from the side end face of the ferrule in order to bring the distal ends of the optical fibers
75
into direct contact with each other.
More specifically, the projecting shape of the optical fibers
75
can be obtained by subjecting the side end face of the ferrule to optical mirror surface finishing by means of buffing (buff polishing). The mirror surface finishing is also called PC (Physical Contact) polishing. According to mirror surface finishing, in order to decrease connection loss of propagation light by Fresnel reflection, the distal ends of the optical fibers
75
are made to project from the side end face of a ferrule by a small amount, and the end faces of opposing optical fibers
75
are brought into direct contact with these projecting distal ends, thereby realizing a low connection loss.
This buff polishing (PC polishing) uses a polishing medium, e.g., diamond abrasive grains. The distal ends of the optical fibers
75
cannot be made to project by a small amount unless the end face of the ferrule is formed of only a resin (plastic) softer than the optical fibers
75
.
This is due to the following reason. When the difference in hardness between the side end face of the ferrule and the optical fibers
75
is small, like the conventional ferrule shown in
FIGS. 10A and 10B
, or when a ceramic material or silicon harder than the optical fibers
75
exists, the finished surface including the optical fibers
75
may become flat, or inversely the distal ends of the optical fibers
75
may be recessed.
In the prior art shown in
FIGS. 11A and 11B
, the side end face of the ferrule is formed of only the molded resin
93
to be separate from the side surface
95
of the ceramic support plate
90
by the distance L.
Generally, a coefficient of linear expansion is large in a resin and small in a ceramic material or silicon. Hence, after a high-temperature molded resin is set, if it is cooled down to room temperature (temperature of the environment where the connector is to be used), a difference in size occurs between the resin and ceramic material.
For this reason, the optical fiber guide holes
91
and guide pin holes
92
appearing in the side end face of the ferrule cannot reflect the high-precision size of the ceramic support plate
90
serving as the core pin guide member.
More specifically, due to the difference in coefficient of linear expansion between the ceramic support plate
90
and molded resin
93
, the hole pitch error may occur at the resin portion corresponding to the distance L between the side surface of the ceramic support plate
90
and the side end face
94
of the molded resin
93
.
In the prior art shown in
FIGS. 11A and 11B
, when L=0 is set, i.e., when the side surface
95
of the ceramic support plate
90
is set to coincide with the side end face of the ferrule, the distal ends of the optical fibers cannot be made to project from the side end face of the ferrule by a small amount in accordance with buffing in the same manner as in the prior art of
FIGS. 10A and 10B
. Accordingly, it becomes impossible to realize a low connection loss by bringing the distal ends of opposing optical fibers into direct contact with each other.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optical connector in which optical fiber guide holes and guide pin holes can be formed at high precision, and a method of manufacturing the same.
It is another object of the present invention to provide an optical connector in which the distal ends of optical fibers can be made to project by a small amount to realize a low connection loss, and a method of manufacturing the same.
In order to achieve the above objects, according to the present invention, there is provided an optical connector comprising a core pin guide member made of a resin to guide a distal end portion of an optical fiber, a molded resin for molding the core pin guide member while exposing one end face thereof, thus constituting a ferrule main body attached to the distal end portion of the optical fiber, the one end face of the core pin guide member being flush with a distal end face of the ferrule main body, and at least one optical fiber guide hole which has an inner wall constituted by the core pin guide member and the molded resin and into which the distal end portion of the optical fiber is inserted.
REFERENCES:
patent: 5815621 (1998-09-01), Sakai et al.
patent: 5862281 (1999-01-01), Shahid
patent: 62-276514 (1987-12-01), None
patent: 62-276513 (1987-12-01), None
patent: 63-246707 (1988-10-01), None
patent: 3-179406 (1991-08-01), None
patent: 3-179405 (1991-08-01), None
patent: 5-34550 (1993-02-01), None
patent: 8-334651 (1996-12-01), None
Kim Robert H.
McGinn & Gibb PLLC
NEC Corporation
Stafira Michael P.
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