Optical waveguides – Accessories
Reexamination Certificate
1999-12-07
2002-01-01
Spyrou, Cassandra (Department: 2872)
Optical waveguides
Accessories
C439S573000, C257S081000
Reexamination Certificate
active
06335996
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fixing structure for optical connectors which fixes a conductive, shielding receptacle housing to a circuit board by means of a tapping screw.
2. Description of the Related Art
FIG. 4
shows a conventional optical connector.
The optical connector
35
is made up of a male optical plug
21
and a female receptacle
36
. The optical plug
21
is inserted into a fitting chamber
37
of the receptacle
36
and locked there through its locking arm
27
. The receptacle
36
has a pair of substantially cylindrical fixing portions
38
at its opposite sides and is fixed to a circuit board
39
with a pair of tapping screws (male screws) threaded into the fixing portions
38
.
The optical plug
21
has a male housing
26
and, as best shown in
FIG. 5
, ferrules
41
(only one is shown) inside the housing which connect to optical fibers
33
. The ferrule
41
is biased forwardly (in a connector-fitting direction) by a coil spring
42
, so that its flange
43
is movable between a stopper
44
and a locking projection
45
inside the housing
26
.
The receptacle
36
has a female housing
26
′ of conductive synthetic resin material and, as best shown in
FIG. 6
, ferrule-receiving cylinders
44
inside the housing
26
′. The fitting chamber
37
of the housing
26
′ is defined by a vertical partition wall
13
, and the receiving chambers
45
project integrally from the partition wall
13
.
The receptacle-making synthetic-resin material contains, for example, carbon fibers to exhibit conductivity and shield against noise-making electric interference from outside and inside the housing
26
′. The housing
26
′ makes contact with a ground circuit (not shown) on the circuit board
39
through the fixing portions
38
at the opposite sides at the rear of the housing, a forwardly-located positioning pin
46
(FIG.
6
).
The receiving cylinder
45
has at the rear side a large diameter portion
45
a
with a sleeve
14
inserted therein. The sleeve
14
consists of an inner waveguide (not shown) of glass or synthetic resin and a metal cylindrical holder. An optical element module
12
is located adjacent to the rear of the receiving cylinder
45
. The sleeve
14
is in contact with the optical element module
12
. The optical element module
12
connects through a lead terminal
19
to the circuit board
39
, and a cover
47
presses the module from the rear toward the receiving cylinder
45
.
The optical element module
12
includes a light emitting element (e.g. light emitting diode) module and a light receiving element (e.g. photodiode) module which are juxtaposed in correspondence to the two optical fibers
33
on the optical plug
21
.
If the optical plug
21
is fitted in the receptacle
36
in
FIG. 4
, a small diameter portion
41
a
at the front of the ferrule
41
in
FIG. 5
advances into a small-diameter portion
45
b
at the front of the receiving cylinder
45
in
FIG. 6
, so that the tip end of the ferrule small diameter portion
41
a
makes contact with the waveguide of the sleeve
14
, and the front end of a ferrule large-diameter portion
41
b
abuts against the front end of the receiving cylinder
45
.
Before the optical plug
21
and the receptacle
36
are fitted together, the housing
26
′ of the receptacle
36
is preliminarily fixed through the positioning pin
46
(
FIG. 6
) to the circuit board
39
, followed by, as shown in
FIGS. 7 and 8
, fully fixing same on the circuit board
39
by means of tapping screws
40
(only one is shown). The circuit board
39
is provided with insertion holes
48
(only one is shown) of diameter equal to or larger than that of the tapping screws
40
, and each fixing portion
38
is provided with a prepared throughhole
49
of diameter smaller than the tapping screw diameter. The tapping screw
40
is threaded into the throughhole
49
, while shaving the inner periphery of the latter.
With the conventional fixing structure for optical connectors, however, when the tapping screw
40
is threaded in as shown in
FIG. 8
, it shaves the inner periphery of the fixing portion
38
to produce shavings
32
which are of the same conductive resin material as the housing
26
′ and which, when dropped on the circuit board
39
, may cause a short in the wiring (not shown) on the circuit board
39
. Further, where the circuit board
39
is used in a vertical position or upside down, the conductive shavings
32
tend to fall and cause an electrically adverse effect on other equipment and electric components located therebelow.
SUMMARY OF THE INVENTION
This invention has been accomplished to overcome the above drawbacks and an object of this invention is to provide a fixing structure for optical connectors in which a conductive housing of a receptacle of an optical connector is tightened to a circuit board with tapping screws (male screws) with resultant production of shavings at the fixing portion of the housing, but yet which is free of a malfunction such as a short caused by the shavings in the wiring on the circuit board.
In order to attain the object, according to this invention, there is provided a fixing structure for optical connectors which comprises: a circuit board; a receptacle having a conductive housing shieldingly connected to the circuit board, the housing having an integral fixing portion with a prepared hole formed therein; and a screw passed through the circuit board and screwed in the prepared hole of the fixing portion to fix the housing to the circuit board, wherein the fixing portion has a sealing wall which closes the prepared hole at a distal end thereof and an enclosed shaving receiver formed in the prepared hole, between the sealing wall and the screw, for retaining shavings produced when the screw is screwed in the prepared hole.
Preferably, the screw comprises a tapping screw, and the prepared hole comprises a hole without a thread.
Preferably, the screw comprises a bolt, and the prepared hole comprises a hole with a female thread.
Preferably, a length of the prepared hole is set greater than a projection length of the screw from the circuit board.
Preferably, the sealing wall of the fixing portion is flush with an outer wall of the housing.
The above and other objects, features and advantages of this invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4428640 (1984-01-01), Pittman
patent: 4842467 (1989-06-01), Armstrong
patent: 5648889 (1997-07-01), Bosli
patent: 5662444 (1997-09-01), Schmidt, Jr.
patent: 5697796 (1997-12-01), Harji et al.
patent: 5738533 (1998-04-01), Furay
patent: 10-284183 (1998-10-01), None
patent: 11-174550 (1999-07-01), None
patent: 11-204969 (1999-07-01), None
Cherry Euncha
Spyrou Cassandra
Yazaki -Corporation
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