Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
1999-04-16
2002-06-11
Font, Frank G. (Department: 2877)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
C385S070000
Reexamination Certificate
active
06402388
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates of optical connectors, and in particular, to an optical connector whose structure accommodates in a housing an optical connector ferrule urged forward towards a butt connection by an urging means.
2. Description of the Related Art
Optical connector ferrules such as those stipulated by JIS C 5981 (Japanese Industrial Standards) have been proposed as optical connectors which switchably connect together optical fibers.
In addition, recently, in consideration of, for example, improving the connection operability of this optical connector ferrule, what are termed MPO connectors (connectors optical connectors whose structure accommodates a multi-core optical fiber connector ferrule stipulated, for example, by JIS C 5981 in a plastic housing) have been used widely.
FIG.
11
and
FIG. 12
show this MPO connector. In
FIG. 12
, this MPO connector
1
is stipulated by Japan Industrial Standards, JIS C 5982, and the International Electronics Standards Committee, EEC publication 1754-7, and has a structure wherein an optical connector ferrule
2
, whose end is PC (physical contact) polished as stipulated by JIS C 5981, etc., and a pin clamp
4
, which clamps a guide pin
3
inserted into this optical connector ferrule
2
in the vicinity (
FIG. 12
, right side) of the back end of the optical connector ferrule
2
, are supported within a sleeve-like housing
5
, the back end of this housing
5
is supported within a sleeve-like coupling
6
, and an abutment force generating coil spring
7
is accommodated by the coupling
6
. The optical connector ferrule
2
can move forward and backward (left to right in
FIG. 12
) in the housing
5
, the housing
5
is urged forward (to the left side in
FIG. 12
) by the housing spring
8
installed separately, and when the optical connector ferrule
2
in inserted into the MPO connector
1
, if the housing
5
is in the end position of the MPO connector
1
and does not move with the optical connector ferrule
2
, then the optical connector ferrule
2
is completely inserted into the housing
5
. When the housing
5
is inserted into the optical connector adapter
10
(see FIG.
11
), the jacks
15
formed on this optical connector adapter
10
engage detachably with the engagement part
9
of the housing
5
side surface, and thereby the inserted state of the MPO is maintained.
Reference numeral
11
in
FIG. 12
is a boot, and from its back end, and the optical fiber
12
(in this figure, optical fiber ribbon cords stipulated by JIS C 6839, etc.), which can terminate in a butt connection due to the optical connector ferrule
2
, is pulled out. The exposed ends of the optical fiber core of the optical fiber
12
, which is an optical fiber ribbon cord, are terminated by the optical connector ferrule
2
, and the cord part is anchored in the housing
5
.
Reference numeral
13
in
FIG. 12
is the interior cavity, and accommodates a coil spring
7
that this optical fiber passes through.
However, in the above-described MPO connector
1
, a pair of MPO connectors
1
are butt connected only by insertion from both sides of the optical connector adapter
10
, and good optical characteristics and connection operability are attained. But, for example, as shown by the line in
FIG. 11
, when the optical fiber
12
pulled out from the back end of one connected MPO connector
1
is being pulled, and a pulling force is applied in the sideways direction on the MPO connector
1
(what is termed ‘side pull’), there is the possibility that the connections will not be aligned and that the characteristics may deteriorate due to sideways pressure being applied to the optical connector ferrules
2
,
2
in a connected state.
That is, when a pulling force is applied in a direction other than the axial direction of the MPO connector
1
, for example, in the direction of the arrow A, to the MPO connector
1
shown in
FIG. 11
, this plastic MPO connector
1
may be slightly displaced due to the small gap which exists between the range of deformability of the connector itself and the optical connector adapter
10
, or the small gap between the optical connector ferrule
2
side surface and the wall surface inside the housing
5
. On the other hand, when side pull above a tolerance value is applied, as shown in the conceptual diagram of
FIG. 13
, because the optical connector ferrule
2
positioned in the housing
5
is displaced as a whole with the MPO connector
1
, displacement of the pressure force on the optical connector ferrule
2
of the MPO connector
1
, which is the counterpart optical connector ferrule
2
of this MPO connector
1
, and misalignment are produced, and thus it is possible that the object of low connection loss cannot be attained. Specifically, at the butt connection between the optical connector ferrules
2
, the PC (Physical Contact) polished ends of the optical fibers
12
a
(bare fibers) exposed at the junction end surface
2
a
of the optical connector ferrule
2
are precisely butt connected by a specified pressure force, and between the several &mgr;m to several tens of &mgr;m diameter cores of the optical fibers
12
a
there is optical coupling, but when a slight displacement of the optical connector ferrule
2
in the MPO connector
1
is produced because of small deformations, etc., due to side pull of the MPO connector
1
, a bias in the pressure force between the optical fibers
12
a
and misalignment of the optical axis are produced, an ideal PC connection state cannot be maintained, and connection loss between the cores of the optical fiber
12
a
in the abutted state is increased, That is, there are cases in which PC connection is possible. In addition, precision in the positioning between the optical connector ferrules
2
can be obtained by the engagement between the guide pin
3
(see
FIG. 11
) and the guide pin holes on the counterpart optical connector ferrule
2
, but when the side pressure applied to the optical connector ferrule
2
becomes large, the optical connector ferrule
2
and the guide pin
3
can be damaged and fail, and the precision of the positioning is lowered.
In consideration of this problem, as shown, for example, in
FIG. 14
, one countermeasure is to provide a large clearance
14
which permits a floating of the optical connector ferrule
2
in the housing of the MPO connector
1
. In this case, the application to the optical connector ferrule
2
of the sideways pulling force applied to the MPO connector
1
due to displacement of the optical connector ferrule in the housing
5
can be largely avoided. However, presently, the support position of the optical connector ferrule
2
in the MPO connector
1
becomes unstable, and it is difficult to fit a guide pin
3
inserted into one optical connector ferrule
2
into the guide pin hole of the other optical connector ferrule
2
, and thus there is the problem that the connection operation between optical connector ferrules
2
deteriorates, and no fundamental solution to this problem has been achieved.
SUMMARY OF THE INVENTION
In light of the above-described problems, it is the object of the present invention to provide an optical connector which:
a) can ensure connection operability by stably maintaining an optical connector ferrule in a specified position in a housing during the connection operation between optical connector ferrules by a positioning retaining part, and can stably and reliably obtain favorable optical connection characteristics such as the intended low connection loss by preventing production of misalignment between optical connection ferrules after completion of the connection even if an external force is applied sideways on the housing; and
b) prevents the external force applied in the sideways direction to the housing from being applied to the optical connector ferrule and maintaining stably and reliably the PC connection state between optical connector ferrules by permitting the rotation of the optical connector ferrule centered on a rotating bearing p
Arikawa Toru
Imazu Natsuka
Nagasawa Shinji
Takaya Masaaki
Takizawa Kazuhiro
Burns Doane , Swecker, Mathis LLP
Nippon Telegraph and Telephone Corporation
Stafiva Michael P.
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