Electrical connectors – Including or for use with coaxial cable
Reexamination Certificate
2002-05-29
2003-08-19
Ta, Tho D. (Department: 2833)
Electrical connectors
Including or for use with coaxial cable
C439S932000
Reexamination Certificate
active
06607399
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coaxial connector that is connected to a coaxial cable at one end for external connection. More particularly, the coaxial connector is connected to a coaxial cable that is run in environments where the coaxial conncetor undergoes thermal shock and variation in temperature.
2. Description of the Prior Art
Referring now to
FIG. 8
, a conventional coaxial cable designed to carry high-frequency signal includes a central conductor
111
. Central conductor
111
is coaxially layered with an insulated cable dielectric
112
, a woven or braided outer conductor
113
and an insulating outer cladding
114
as shown. Referring now to
FIG. 9
, in a conventional design coaxial connector
100
is affixed to one end of the the coaxial cable and enables connection to other equipment or another coaxial cable.
Conventional coaxial connector
100
includes a central contact
101
formed by bending a conductive metal sheet. An insulating housing
103
surrounds a contact receiving hole
102
formed to receive the central contact
101
. A cylindrical grounding shell
104
mounts on an outer surface of insulating housing
103
.
Central contact
101
has a forward (to right-hand side in
FIG. 9
) portion formed as a plate-spring-like contact piece
108
and a rearward portion formed as a conductor clamping barrel
106
,
108
. to connect with central conductor
111
. Contact receiving hole
102
extends through insulating housing
103
lengthwise and receives central conductor or switch for contact
101
during an assembly. Contact receiving hole
102
also guides a plug pin
120
of, a mating connector, into contact with contact piece
108
.
Referring now to
FIG. 10
, an assembly sequence for connecting a coaxial cable to coaxial connector
100
is shown and described. First, a cylindrical clamp
107
is placed on coaxial cable, and then a grounding shell
104
is slid onto insulating housing
103
from behind to form a unitary structure. Next, central conductor
111
is inserted into clamping barrel
106
. Central conductor
101
has a U-like cross section formed at rear end portion of central contact
101
.
At same time central contact
101
is inserted into insulating housing
103
, a shell connecting part
105
, that extends rearwardly from grounding shell
104
, is inserted between cable dielectric
112
and outer conductor
113
. Therefore, outer conductor
113
and outer cladding
114
are clamped together by clamp
107
which was fitted on coaxial cable.
Since grounding shell
104
is fixed to insulating housing
103
, coaxial connector
100
is mechanically connected to coaxial cable. Also, central contact
101
and grounding shell
104
are electrically connected to central conductor
111
and outer conductor
114
, respectively.
When a coaxial cable connected to coaxial connector
100
above, is used in environments where wide temperature variations are encountered, central conductor
111
and cable dielectric
112
typically expand or contract relative to outer cladding
114
. This movement variation is due to the fact that central conductor
111
, cable dielectric
112
, outer conductor
113
and outer cladding
114
have different thermal expansion coefficients.
When the expansion or contraction occurs, since outer conductor
113
and outer cladding
114
are fixed to insulating housing
103
through grounding shell
104
, central contact
101
, which is fixed to central conductor
111
, is likely to be pulled out of insulating housing
103
. A protrusion
102
a
is located at an intermediate portion of the central contact
101
. Protrusion
102
a
prevents rearward movement of central contact
101
by engaging a locking stepped portion
101
a
protrusively provided in contact receiving hole
102
. This is to prevent central conductor
111
from being pulled out of insulating housing
103
even if contraction of central conductor
111
occurs.
Conventional coaxial connector,
100
protrusion
101
a
is in central contact
101
. Contact receiving hole
102
is provided with stepped portion
102
a
for engaging protrusion
101
a
. Stepped portion
102
a
is formed by cutting a U-groove
109
(see
FIG. 10
) lengthwise into the interior surface of contact receiving hole
102
at front end face of insulating housing
103
after it is removed from a molding die.
This structure may, due to thermal expansion or contraction, allow central contact
101
to tilt and partly enter into U-groove
109
of contact receiving hole
102
. If control contact
101
is tilted, plug pin
120
will not correctly make resilient contact with contact piece
108
once inserted into contact receiving hole
102
. Also, plug pin
120
must be inserted with greater force causes plastic deformation of contact piece
108
.
Further, since U-groove
109
creates a detrimental air gap at an asymmetrical position about central contact
101
, distortion will occur which will not match characteristic impedance of coaxial cable, this distortion will degrade high-frequency signal transmission characteristic.
Moreover, it is necessary to insert central contact
101
into contact receiving hole
102
while bringing protrusion
101
a
into engagement with stepped portion
102
a
, this impairs efficiency of assembling.
Also, since central contact
101
is inserted into contact receiving hole
102
until protrusion
101
a
goes beyond stepped portion
102
a
, they are always separated by a slight gap &dgr; as illustrated in FIG.
9
. Inevitably, after assembly, central contact
101
moves as central conductor
111
contracts.
Thus, there is still a need in art to devise a coaxially connector that will hold central contact in place regardless of thermal conditions and expansion and contraction caused therefrom.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a coaxial connector that, even if thermally shocked, securely holds the central contact in place within the insulating housing and prevents breakage of the central contact.
Another object of the present invention is to provide a coaxial connector wherein, even if thermally shocked, securely retains and prevents degradation of the high-frequency transmission characteristic of the coaxial cable.
Another object of the present invention is to provide a coaxial connector that can be assembled with high efficiency.
It is the foregoing and various of drawbacks of the prior art which the present invention seeks to overcome by providing a coaxial connector that includes a central connector having a forward portion where a contact portion makes electrical contact with a central terminal of the mating connector. The central connector also has a rearward portion where a conductor connecting portion is crimped into contact with a central conductor of a coaxial cable. An insulating housing is bored lengthwise through a contact receiving hole to receive the central contact in place, and also, a grounding shell is mounted over the insulating housing and has a shell connecting portion extending from a rear end of the insulating housing. The grounding shell is crimped into contact with an outer conductor of the coaxial cable. Additionally, a marginal portion of the insulating housing around the conductor connecting portion, is thermally fusion welded to fixedly secure the central contact to the insulating housing when the terminal of the central conductor is brought into contact by crimping from the outside.
The terminal of the central conductor is crimped to the marginal portion of the conductor connecting portion from the outside of the marginal portion. Thus, the crimping action makes the surface of the marginal portion uneven and the thermally fused material of the insulating housing adheres to the uneven-surfaced marginal portion of the conductor connection portion. The adhering of the fused material firmly fixs the insulating housing and the central contact to each other.
Accordingly, the central contact will not be displaced in the insulating housing by the
Abe Kimihiro
Endo Takayoshi
Tagashi Kouji
Darby & Darby
Ta Tho D.
Yazaki -Corporation
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