Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2000-03-10
2002-10-01
Ullah, Akm E. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
Reexamination Certificate
active
06457876
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical device that may be connected to an optical fiber cable and used in optical communication. In particular, the invention relates a surface-mountable optical device that may be mounted on a circuit board and assembled with other components.
2. Description of Related Art
Various optical devices and their peripheral components have been devised and developed heretofore for optical communication. One of such optical device and its peripheral components are shown in
FIGS. 16 and 17
.
FIG. 16
is a schematic plan view for illustrating a conventional optical device and its peripheral components and
FIG. 17
is a schematic side view of the assembly where the optical device and its peripheral components are mounted on a circuit board
5
.
In these figures, the reference numeral
28
denotes an optical device,
3
denotes an optical fiber cable comprising a cable wire
3
a
and a standard plug
3
b
, and
29
denotes an adaptor for optically coupling the optical device
28
and the optical fiber cable
3
. The reference numeral
5
denotes a circuit board on which the optical device
28
is mounted. The reference numeral
30
is a device body
30
in which internal optical components (not shown) and the like are integrated. The reference numeral
31
denotes leads for securing the device body
30
on the circuit board
5
and electrically connecting the above optical components to external components (not shown). The reference numeral
32
denotes an optical cable protruded from the device body
30
, and also
33
denotes a plug fixed on the tip of the optical cable
32
.
The conventional optical device
28
and the peripheral components are assembled by: soldering leads
31
on the circuit board
5
; and then coupling the plug
33
with the standard plug
3
b
through the adapter
29
.
As the optical device is assembled as described above, there are several problems that lie within the step of mounting both the optical device and its peripheral components on the surface of the circuit board and also lie within their usage patterns.
Firstly, for a manufacturer, the conventional optical devices cannot be provided in quantity by automatically controlled manufacturing process because each of them has the optical fiber cable
32
that extends from the device body
30
irrespective of its length. For a user, the conventional optical device
28
cannot be mounted on the circuit board
5
simultaneously with other components. Thus each part of the optical device
28
needs to be manually mounted on the circuit board
5
after mounting the other components on the circuit board
5
.
Secondary, most components currently available have surface-mountable leads. For the conventional optical device
28
described above, the number of terminals to be used in electrical contact between the optical device
28
and other components may be 8 to 20. Therefore, the leads are provided as through-hole leads in DIP (Dual Inline Package) in consideration of a strength of securing the optical device
28
on the circuit board
5
against, for example, pulling the optical fiber cable
32
accidentally. It means that there is no component that can be installed on the backside of the circuit board
5
on which the optical device
28
is mounted, standing in the way of attaining higher packing density.
Thirdly, the required number of components is considerable. The conventional optical device
28
requires a connecting means such as the adapter
29
mentioned above for connecting the optical fiber cable
32
that extends from such a device to the standard plug
3
b of another cable
3
in practical use.
To solve the above problems, several approaches have been proposed so far in the step of mounting an optical device and its peripheral components on a circuit board and the usage pattern thereof.
FIG. 18
is a schematic plan view for illustrating the construction of another conventional optical device (hereinafter, referred as a second conventional optical device) and its peripheral components.
In the figure, the reference numeral
34
denotes a ferrule protruding from one end of the device body
30
in which an optical fiber (not shown) is coaxially provided. The reference numeral
35
denotes an optical fiber cable designed specifically for the device body
30
. The optical fiber cable
35
comprises a cable wire
36
, a ferrule
37
, and a plug
38
. The reference numeral
39
denotes a sleeve for positioning the ferrule
37
of the specific optical cable
35
and the ferrule
34
of the device body
30
together with great precision. The reference numeral
29
denotes an adaptor for optically coupling between the plug
38
and the standard plug
3
b.
In addition, the reference numeral
41
denotes a female connector fixed on the device body
30
, and
42
denotes a male connector which is provided around the ferrule
37
.
Accordingly, the optical device and its peripheral components are constructed as described above, so that the optical device can be configured in which the optical fiber cable
35
extends from the surface of the device body
30
by mounting the device body
30
on a circuit board (not shown in
FIG. 18
) and then coupling the connectors
41
,
42
together through the sleeve
39
.
The second conventional optical device is designed so that the optical fiber cable
35
does not extend from the device body
30
in itself. Thus, the device body
30
can be automatically mounted on the substrate
5
together with other components by means of batch reflowing.
In spite of the improved configuration of the second conventional optical device, a sufficient strength securing the device
28
on the circuit board
5
against an externally applied force caused by mating and unmating of the optical fiber cable
3
cannot be ensured. Notably, an insufficient securing strength becomes increasingly serious if surface-mountable leads are used. Thus, the second conventional optical device requires through-hole leads. In this case, however, it stands in the way of attaining simultaneous mounting with other components and higher packing density.
Furthermore, the second conventional optical device cannot attain a sufficient securing strength against an externally applied force caused by directly mating and unmating the standard plug
3
b
of the optical fiber cable
3
with the optical device. Thus, the device body
30
should be connected to the specific optical fiber cable
35
, followed by connecting such a cable
35
to the standard plug
3
b of the optical fiber cable
3
. As a result, the number of components required increases considerably.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a surface-mountable optical device which can be installed on a circuit board simultaneously with other components by means of surface-mount technology and directly connecting to a standard plug of an optical fiber cable for simultaneously attaining the reduction in component count and an increased packaging density.
In the first aspect of the invention, there is provided a surface-mountable optical device comprising:
an optical component unit having a package, an inner optical components installed in the package, a plurality of surface-mountable leads protruded from the package, and a ferrule optically coupled to the inner optical components and protruded from the package in a predetermined direction; and
a receptacle unit having a receptacle for holding an optical fiber cable to ensure an optical coupling between the optical fiber cable and the ferrule, and a plurality of surface-mountable leads fixed on the receptacle,
wherein
the surface-mountable optical device and the receptacle unit are provided independently, and the receptacle unit is inserted into the surface-mountable optical unit along the predetermined direction.
Here, the receptacle unit may be formed to ensure the optical coupling between the optical fiber cable and the ferrule when a space between an outermost surface-mountable
Burns Doane , Swecker, Mathis LLP
Connelly-Cushwa Michelle R.
Mitsubishi Denki & Kabushiki Kaisha
Ullah Akm E.
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