Optical waveguides – With optical coupler – Particular coupling structure
Reexamination Certificate
2000-03-27
2002-10-01
Spyrou, Cassandra (Department: 2872)
Optical waveguides
With optical coupler
Particular coupling structure
C385S033000, C385S088000, C385S098000, C385S092000
Reexamination Certificate
active
06459835
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical connector with sleeves located between optical fibers and light-receiving/light-transmitting modules and being capable of making optical contacts therebetween.
2. Description of the Related Art
A typical optical connector with sleeves located between the optical fibers and the optical-receiving/optical transmitting module is disclosed in J-UM-6-33443 by the inventors of the invention.
FIG. 17
is a horizontal sectional view of a conventional optical connector, and
FIG. 18
is a horizontal sectional view of the receptacle shown in FIG.
17
. In
FIGS. 17 and 18
, reference numeral
1
denotes a sleeve, and reference numeral
2
denotes an optical connector.
Sleeves
1
are attached to a receptacle (connector on the side of a device) constituting the optical connector
2
. These sleeves
1
are arranged between optical element modules
4
(consisting of a light-receiving module and a light-emitting module) and a pair of optical fibers
6
which are attached to an optical plug (connector on the side of the optical fiber) constituting the optical connector
2
, respectively. The sleeves
1
serve to make an optical connection between the light-receiving/light-transmitting modules
4
and optical fibers
6
.
A more detailed explanation will be given of the optical connector
2
as well as the sleeves
1
.
The optical connector
2
includes the receptacle
3
and the optical plug
5
fit into the receptacle
3
.
The receptacle
3
, as shown in
FIGS. 17 and 18
, has a housing
7
made of synthetic resin. and having a pair of housing chambers
8
. The housing chambers
8
each houses a light-receiving/light transmitting module
4
which is supported by a back sheet
9
made of elastic material such as rubber. The rear of each of the housing chambers
8
is covered with a cap
10
. The receptacle
3
has a pair of receiving cylinders
12
which are arranged in front of the housing chambers
8
, and extended forward so as to accord with the respective axes of lenses
11
. The sleeves
1
are inserted in the receiving cylinders
12
, respectively. The sleeve
1
can be formed by grinding both end surfaces of the optical fiber composed of a core and a cladding (not shown) after it has been secured to a cylindrical holder
14
.
On the other hand, the optical plug
5
fits in the receptacle
3
, as seen from
FIG. 17 and 19
which is a horizontal sectional view of the optical plug shown in
FIG. 12
, includes a pair of ferule assemblies
15
each covering the optical fiber with its end face exposed at the tip of the assembly, a plug housing
17
with a pair of cylindrical partitions
16
for protecting the ferule assemblies
15
housed therein, a spring cap
17
fit over the plug housing
18
and a boot
19
fit over the rear of the spring cap
18
.
The plug housing
17
has shoulders
17
a
each to be engaged with a flange
15
a
formed on the. rear half of the periphery of each ferule assembly
15
. The ferule
15
is urged forward normally by a spring
20
which is located between the flange
15
a
and inner cylinder
18
a
of the spring cap
18
.
As shown in
FIG. 19
, by engagement between the flange
15
a
and shoulder
17
a
, the tipA of the ferule assembly is always pulled more internally than the tip of the plug housing
17
. The tip A of the ferule assembly
15
corresponds to the light-incident/emitting face of the optical fiber
6
.
As regards the above configuration, referring to
FIG. 17
, an explanation will be given of connection between the receptacle
3
and the optical plug
5
.
When the receptacle
3
is fit over the optical plug
5
, the receiving cylinders
12
advance into the plug housing
17
, and the ferule assemblies
15
also advance into the receiving cylinders
12
. At this time, the ferule assembly
15
is brought into contact with the tip of the receiving cylinder
12
and a suitable contact pressure is kept by the elastic force by the spring
20
.
In this state, the tip A (
FIG. 19
) and sleeve
1
are arranged with a minimum gap (not shown) kept. Therefore, the loss of the gap can be minimized.
The prior art described above, in which the sleeve
1
has an optical fiber
13
and is formed in a ring-shape, presents the following problems.
As shown in
FIG. 20
, with respect to a light beam c
1
(within a range of a critical angle) which is propagated through an optical fiber
6
and sleeve
1
along an optical path indicated by arrow in
FIG. 20
, when the light receiving face
4
a
of the light receiving element module
4
is smaller than the light-emitting face
1
a
of the sleeve
1
(the width of the module
4
is smaller by d than that of the optical fiber
13
on the one side with respect to a center line), the light beam c
1
may not be received by the light receiving element module
4
. This is one of causes reducing the transmission efficiency.
Therefore, by designing the optical connector so that light-receiving module
4
can receive such optical beam c
1
, the transmission efficiency can be improved.
Although not shown, when the light beam emitted from the light emitting face (not shown) of the light emitting element module is diffusive-LED light, part of the light cannot enter the sleeve
1
.
Even if such a light beam is incident on the sleeve
1
, it becomes a light beam c
2
out of the critical range of angle (&thgr;). Therefore, the light c
2
does not reflect totally but permeates through the sleeve
1
. The light c
2
will be not be propagated.
Therefore, by designing the optical connector so that the light such as the light beam c
2
is totally reflected, it is expected that the transmission efficiency can be improved.
Further, the prior art intends to minimize the gap loss to improve the transmission efficiency. However, a slight gap between the optical fiber
6
and sleeve
1
and axis displacement therebetween may influence the transmission efficiency.
There is also a problem relative to productivity of the sleeve
1
as well as the problem of the transmission efficiency.
Specifically, as described above, in order to improve the optical characteristic (transmission efficiency of light) of the sleeve
1
, after the optical fiber
13
is inserted in and attached to the holder
14
, both end surfaces of the optical fiber
13
as well as the holder
14
must be ground using abrasives of plural grain sizes. Thus, production of the sleeve
1
requires many manufacturing steps inclusive of necessary previous steps of making its components, and is inferior in productivity.
Further, production of the: sleeve
1
, which requires monitoring the production status of its components and testing the size, is involved with complicate production management. This deteriorates the productivity of the sleeve and increases the production cost.
It is also demanded to assemble the sleeve with a receptacle smoothly.
SUMMARY OF THE INVENTION
An object of the invention is to provide an optical connector which can improve its transmission efficiency and enhance its productivity to reduce the production cost.
In order to attain the above object, in accordance with the present invention, there is provided an optical connector comprising a pair of optical fibers, light receiving/transmitting modules and sleeves each located therebetween and making an optical connection therebetween, wherein each the sleeves has a light guiding passage which is tapered from each the optical fibers toward the light receiving/transmitting modules, thereby forming a conical shape with an sloped side wall and a first end face having a reduced diameter of the light-guiding passage and arranged oppositely to each the light receiving/transmitting modules.
In this configuration, when the light propagated through the optical fiber is incident on the sleeve, it is propagated through the light-guiding passage while while repeating total reflection on the sloped side wall and gradually converged toward the light-receiving module.
On the other hand, the light which falls out of a critical angle in
Kondo Hiroyuki
Matsushita Junichi
Nagaoka Yasutaka
Suzuki Nobuhiko
Suzuki Norihito
Armstrong Westerman & Hattori, LLP.
Assaf Fayez
Spyrou Cassandra
Yazaki -Corporation
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