Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2001-11-19
2004-04-20
Sanghavi, Hemang (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S094000
Reexamination Certificate
active
06722794
ABSTRACT:
BACKGROUND OF THE INVENTION
This application claims the benefit of a Japanese Patent Application No. 2001-133675 filed Apr. 27, 2001, in the Japanese Patent Office, the disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to optical modules and optical module producing methods, and more particularly to an optical module, having an optical connector, which is detachably and optically coupled and is covered by a molded resin for protection at the time of production, and to an optical module producing method for producing such an optical module.
2. Description of the Related Art
In optical communication apparatuses and information processing apparatuses which process optical signals, there are demands to realize a high-density optical signal transmission at a high speed and a high capacity. On the other hand, there are also demands to reduce the size and cost and to simplify the structure of a transmitter section and a receiver section of a terminal equipment which transmits and receives the optical signal. Hence, there are similar demands with respect to various kinds of optical modules.
In the optical module which is coupled to an optical fiber of the transmission line, it is desirable that the optical module is detachably connected directly by an optical connector. Hence, the so-called pig-tail type optical module, which has the optical connector at a tip end of an optical fiber having a suitable length, is popularly used. However, the provision of the optical fiber introduces various problems.
For example, when assembling the optical module by an automatic assembling process, the provision of the optical fiber interferes with the full automation of the assembling process. In addition, when transporting the optical module, it is necessary to accommodate the optical module within a transporting case and to handle the optical module with care. Furthermore, when mounting a main body of the optical module within an apparatus, it is necessary to take appropriate measures such as mounting the optical fiber by winding the optical fiber to a predetermined diameter.
In view of the above, it is possible to effectively reduce the size of the optical module, by providing an optical connector section without via an optical fiber, as shown in a cross sectional view of FIG.
1
.
An optical module
1
has a projecting ferrule
2
, for an optical connector, provided with an optical fiber at a central portion on a tip end portion on the left side of the optical module
1
in FIG.
1
. The periphery of the ferrule
2
fits in a first cylindrical member
3
, and the periphery of the first cylindrical member
3
fits in a second cylindrical member
4
. An end surface of the second cylindrical member
4
is connected to an end surface of an optical device
5
which is made of a sealed container. An optical element, such as a laser diode which is used as a light emitting element, is provided within the optical device
5
.
A plurality of terminals
6
for connecting to electrical circuits is provided on the right side of the optical device
5
in FIG.
1
. The terminals
6
are connected to a circuit board
7
having various electrical circuits. Terminals
8
for connecting to an external circuit are provided on both sides of the circuit board
7
.
A synthetic resin molded portion
9
covers, that is, encapsulates, the periphery of the optical module
1
, excluding the tip end portion of the ferrule
2
and the ends of the terminals
8
, to form the optical module
1
.
The synthetic resin molded portion
9
has an engaging part
11
which projects on both sides in a direction perpendicular to an axis direction of the ferrule
2
and the first cylindrical member
3
. The engaging part
11
includes a sloping surface
12
located on a left side in
FIG. 1
, an engaging surface
13
perpendicular to the axis direction located on the right of the sloping surface
12
, a flat guide portion
14
located on the left of the sloping surface
12
, and a constricted portion
15
located on the right of the engaging surface
13
. These elements of the engaging part
11
form a connector section
16
of the optical module
1
.
In
FIG. 1
, the cross section of the synthetic resin molded portion
9
is shown along the solid line to facilitate understanding of the positional relationship of the optical device
5
and the circuit board
7
.
FIGS. 2A and 2B
respectively show a plan view and a cross sectional view of an optical connector
21
of an optical fiber cord which forms an optical fiber transmission line that connected to the optical module
1
. In the optical connector
21
, a cylindrically coiled spring
24
having a slit
23
in the axis direction, and also referred to as a split sleeve, is fit into a central penetration hole in a synthetic resin molded housing
22
. A ferrule
25
is press-fit within the cylindrically coiled spring
24
so as to push and spread the diameter of the cylindrically coiled spring
24
.
A holder
26
is press-fit and connected to the left side of the ferrule
25
in
FIGS. 2A and 2B
. An optical fiber cord
27
is fixed to the holder
26
. In addition, the optical fiber of the optical fiber cord
27
penetrates the center of the ferrule
25
and is connected to the ferrule
25
. The end of the optical fiber is exposed at the end portion of the ferrule
25
, and is optically polished.
A compressed coil spring
28
is inserted between the housing
22
and the holder
26
. The compressed coil spring
28
, together with the holder
26
, pushes against the ferrule
25
and urges the ferrule
25
towards the rightward direction in
FIGS. 2A and 2B
.
A pair of engaging leaf springs
31
which project towards the axis direction are provided in parallel on the right side of the housing
22
in
FIGS. 2A and 2B
. Each engaging leaf spring
31
has an engaging projection
32
on a tip end thereof, and a guide portion
33
on an inner side of the engaging projection
32
. The engaging projections
32
of the pair of engaging leaf springs
31
confront each other, and the guide portions
33
of the pair of engaging leaf springs
31
confront each other.
A sloping surface
34
and an engaging surface
35
which is perpendicular to the axis direction are formed on the tip end of the engaging projection
32
. The engaging projection
32
and the guide portion
33
are separated by an intermediate space or gap which extends in a direction perpendicular to the paper in
FIGS. 2A and 2B
.
The optical connector
21
is known as an EZ type optical connector, and the diameter of the ferrule
25
is 1.25 mm. The housing
22
is made of a synthetic resin having mechanical resilience. The cylindrically coiled spring
24
is made of a resilient material such as zirconia ceramics or metal. The ferrule
25
is made of zirconia ceramics. The holder
26
is made of a molded synthetic resin, and the compressed coil spring
28
is made of a known metal coil.
When optically connecting the optical module
1
and the optical connector
21
, the engaging projection
32
of the optical connector
21
is fit over the connector section
16
of the optical module
1
, as shown in
FIG. 3A
which shows the optical connector
21
in cross section.
In other words, the optical connector
21
is pushed so that the guide portions
14
fit into the intermediate spaces of the upper and lower engaging projections
32
. Hence, the sloping surfaces
12
and
34
contact each other, and the engaging leaf springs
31
of the optical connector
21
are spread on both sides against the spring force by this contact. As a result, the engaging projections
32
fit into the constricted portions
15
of the connector section
16
as shown in
FIG. 3B
, and the engaging leaf springs
31
are restored to their original states by the spring force.
During the above process, the tip end of the ferrule
2
fits into the cylindrically coiled spring
24
against the spring force of the cylindrically coiled spring
24
. Hence, the tip end of the ferrule
2
is positioned to
Fujitsu Limited
Rojas Omar
Sanghavi Hemang
Staas & Halsey , LLP
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