Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
2000-11-28
2003-04-01
Nasri, Javaid (Department: 2839)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
active
06540408
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a waveguide connecting method and structure for connecting waveguides to each other and, more particularly, to a waveguide connecting method and structure for connecting waveguides to each other by using a shim which closes a gap formed between the end faces of the waveguides.
When connecting waveguides to each other, if a gap is formed between the end faces of the waveguides or the flange surfaces of flanges formed on the ends of the waveguides, a reflection wave is generated at the connecting portion, and a loss (reflection loss) due to the reflection wave increases. In order to improve the reflection characteristics by decreasing the reflection loss caused at the waveguide connecting portion, a choke flange is generally used.
If the flange surfaces outside a choke groove cannot be brought into tight contact with each other, a sufficient effect cannot be obtained. A waveguide connecting structure for obtaining better reflection characteristics is proposed in Japanese Patent Laid-Open No. 9-312501 (reference
1
).
FIG. 8
shows the sectional structure of the connecting portion of two waveguides
110
and
120
disclosed in reference
1
. Referring to
FIG. 8
, a ring-like groove
116
is formed in the surface of a flange
112
of the waveguide
110
to surround an opening
111
a
. A thin metal plate
117
with spring properties and a radio wave absorber
118
are disposed in the groove
116
. The metal plate
117
is bent to have an uneven section, and some bent portions
117
a
and
117
b
project from its flange surface
112
a.
When the waveguide
120
is to be connected to the waveguide
110
, the bent portions
117
a
and
117
b
are forced backward as they are pushed by a flange surface
122
a
of the waveguide
120
. Hence, when connecting the waveguides
110
and
120
, the bent portions
117
a
and
117
b
of the metal plate
117
come into tight contact with the flange surface
122
a
of the waveguide
120
. At this time, during connection, even if a gap is formed due to damage and unevenness of the flange surfaces
112
a
and
122
a
of the waveguides
110
and
120
, it is closed midway by the bent portions
117
a
and
117
b.
In the conventional waveguide connecting structure described above, the position where the gap is closed by the metal plate
117
of the waveguide
110
is away from the opening
111
a
of the waveguide
110
and an opening
121
a
of the waveguide
120
, that is, from the interiors of the waveguides. Since the discontinuity of the connecting portion itself of the waveguides
110
and
120
is not solved, a sufficient effect cannot be obtained in improving the reflection characteristics.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a waveguide connecting method and structure that can provide good reflection characteristics when waveguides are connected to each other.
In order to achieve the above object, according to the present invention, there is provided a waveguide connecting method comprising the steps of fabricating a shim with a cylindrical portion and a flange which projects from one end of the cylindrical portion outwardly, the cylindrical portion having an outer diameter substantially equal to an inner diameter of a first waveguide which is to be connected to a second waveguide, inserting the other end of the cylindrical portion of the shim into the first waveguide, and urging the second waveguide against the first waveguide, with an end face of the second waveguide being in contact with the flange of the shim, until the end face of the second waveguide abuts against an end face of the first waveguide.
REFERENCES:
patent: 3374450 (1968-03-01), Stewart
patent: 3784939 (1974-01-01), Maeda et al.
patent: 3786377 (1974-01-01), Spinner
patent: 5432879 (1995-07-01), Lee
patent: 5563971 (1996-10-01), Abendschein
patent: 820455 (1951-11-01), None
patent: 654135 (1951-06-01), None
patent: 58-47301 (1983-03-01), None
patent: 60-105197 (1985-06-01), None
patent: 1-95801 (1989-06-01), None
patent: 3-28801 (1991-03-01), None
patent: 4-75403 (1992-07-01), None
patent: 8-170528 (1996-07-01), None
patent: KOKAI 9-312501 (1997-12-01), None
patent: 9-312501 (1997-12-01), None
patent: 10-318465 (1998-12-01), None
European Search Report dated Mar. 22, 2002.
McGinn & Gibb PLLC
Nasri Javaid
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