Electrical connectors – Including or for use with coaxial cable – Having crimpable metallic cable conductor grip
Reexamination Certificate
2002-09-10
2004-03-23
Ngo, Hung V. (Department: 2831)
Electrical connectors
Including or for use with coaxial cable
Having crimpable metallic cable conductor grip
C439S616000
Reexamination Certificate
active
06709290
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a connection of such a cable as a wiring harness to electric devices or the like in a motor vehicle or the like. More particularly, the invention relates to a connection structure of a shielding connector for relay connecting a shielded cable to a printed circuit board in the electric device and an antenna.
An electric device in a motor vehicle, such as a car navigation system, contains a control-use printed circuit (PC) board on which electronic parts, IC (integrated circuit) packages and others are mounted. Recently, a transmission speed of an electric signal transmitted to and from the PC board is increased (viz., the transmission signal frequency is increased). Further, board patterns of the PC board are densely arranged. To transmit such high frequency signals, a shielded cable designed to be adapted for the high frequency signal transmission is generally used. With increase of the transmission signal frequency, also in the shielding connector for relay connecting the shielded cables, there is an increasing demand to take some measure for the high frequency signal transmission.
A called coaxial cable is known as an example of the shielded cable. Usually, the shielded cable has a coaxial structure having a signal conductor which is formed by binding a plurality of element wires and serves as a signal transmission line, a shielding conductor consisting of a plurality of braided element wires, an insulating member interposed between the signal conductor and the shielding conductor, and a sheath covering the outer periphery surface of the shielding conductor. The shielding conductor closely covers the outer periphery of the insulating member to thereby electrically shield the signal conductor.
Generally, the shielding connector for relay connecting coaxial cables for transmitting high frequency signals is formed with an internal conductor terminal to be connected to the signal conductor for transmitting a high frequency signal, an outer conductor terminal which is to be connected to the shielding conductor of the braid wire or the like and covers the internal conductor terminal for the electromagnetic shielding purpose, and a dielectric body of a predetermined dielectric constant provided between the internal conductor terminal and the outer conductor terminal. The shielding connector individually and electrically relay connects the signal conductor and the shielding conductor of a shielded cable to be relay connected, which are exposed by peeling the connection terminal and the insulating member off the shielded cable.
A typical example of such a shielding connector is disclosed in the Unexamined Japanese Patent Publication No. 2000-173725.
FIG. 4A
is a longitudinal sectional view showing the shielding connector, and
FIG. 4B
is a cross sectional view taken on line B—B in FIG.
4
A. As shown, an insulating member and a sheath
71
c
of a coaxial cable
71
are peeled off to expose a signal conductor
71
a
and a shielding conductor
71
b
. A connection process of connecting the shielding connector to the coaxial cable follows. To start, a press connection part
72
a
of an inner conductor terminal
72
is press connected to the exposed signal conductor
71
a
. Then, the inner conductor terminal
72
is forcibly inserted into and fixed to a press-fitting bore
74
a
of a dielectric body
74
, which has been put in and assembled to an outer conductor terminal
73
. The shielding conductor
71
b
as is inverted on the coaxial cable
71
is put on a press connection part
73
a
of the outer conductor terminal
73
, and compressed by the latter. Then, the sheath
71
c
and the shielding conductor
71
b
are both clamped with the press connection part
73
a
of the outer conductor terminal
73
. Here, the connection work is completed.
In the step in which the inner conductor terminal
72
is forcibly inserted into and fixed to the dielectric body
74
, which the step is executed before the step of clamping the shielding conductor with the press connection part
73
a
of the outer conductor terminal
73
, a terminal insertion hole
73
b
, which is formed by opening the upper surface of the outer conductor terminal
73
to an upper part of the drawing, is utilized as a press-fitting work space, whereby the inner conductor terminal
72
may easily be press inserted into the connector by means of a press-fitting jig or another tool.
Another conventional art is disclosed in the Unexamined Japanese Utility Model Application Publication No. Hei 3-80982.
FIG. 5A
is a longitudinal sectional view showing the shielding connector and
FIG. 5B
is a cross sectional view taken on line C—C in FIG.
5
A. As shown, an insulating member and a sheath
81
c
are peeled off a coaxial cable
81
to expose a signal conductor
81
a
and a shielding conductor
81
b
. In a step of connecting the shielding connector to those exposed parts, a dielectric body
84
and an inner conductor terminal
82
are assembled to an outer conductor terminal
83
in advance. The signal conductor
81
a
and the shielding conductor
81
b
are respectively put on a press connection part
82
a
of the inner conductor terminal
82
and a press connection terminal
83
a
of the outer conductor terminal
83
to which those conductors are to be connected. The former conductors and the latter terminals are press connected together simultaneously by using a press connection jig D or another appropriate jig. Then, the connection work is completed. For the press connection work of connecting the press connection part
82
a
of the inner conductor terminal
82
, a press-inserting hole
83
b
is opened to an upper part and a lower part in the vicinity of the press connection part
82
a
of the outer conductor terminal
83
. With the press-inserting hole, the press connection part, together with the coaxial cable
81
, is press connected simultaneously to thereby providing easy connection.
Generally, the characteristic impedance of the transmission line for the high frequency signal transmission is set at 50 &OHgr;, for example. The high frequency signal transmission line is impedance matched to the signal transmission paths of the PC board of the electric device to be relay connected or the cable also to be relay connected. If the transmission path contains a part where the characteristic impedance is not matched (impedance mismatching part), the signal reflects at the impedance mismatching part to reduce the transmission efficiency, and noise is generated thereat. Accordingly, the shielding connector as a relay connection part in the transmission path is also impedance matched to the signal transmission line.
The impedance of the shielding connector is matched to that of the shielded cable as the transmission line by adjusting a “ratio of the inside diameter of the body of the outer conductor terminal and the outside diameter of the terminal part of the inner conductor terminal” and “a dielectric constant of the dielectric body”. As shown in
FIGS. 4 and 5
, the diameter of the press connection part
72
a
(
82
a
) after the inner conductor terminal is press connected is designed to have a size and a shape, while giving priority to a reliability of its electrical connection to the signal conductor. Usually, it is smaller than the diameter of the terminal body. It does not satisfy the “ratio of the inside diameter of the body of the outer conductor terminal and the outside diameter of the terminal part of the inner conductor terminal”. Further, a part of the wall of the outer conductor terminal near the press connection part is opened to secure a space for the work using the press-fitting jig or press-inserting jig. The press connection part as the connection part to the signal conductor of the inner conductor terminal is not covered in all directions with the outer conductor terminal provided for the electromagnetically shielding purpose and the dielectric body, and is exposed to air having a dielectric constant of &egr;r=1. For this reason, the impedance of this
Autonetworks Technologies Ltd.
Ngo Hung V.
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