Electrical connectors – Including or for use with coaxial cable – Having crimpable metallic cable conductor grip
Reexamination Certificate
2003-03-06
2004-10-26
Feild, Lynn (Department: 2839)
Electrical connectors
Including or for use with coaxial cable
Having crimpable metallic cable conductor grip
Reexamination Certificate
active
06808417
ABSTRACT:
The present disclosure relates to the subject matter contained in Japanese Patent Application No.2002-104242 filed on Apr. 5, 2002, which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a connector for connection to a cable having a shielding conductor such as a coaxial cable, and more particularly to a high-frequency connector, which achieves the characteristic impedance matching with a transmission path and can be easily mounted on and connected to a cable end.
2. Description of the Related Art
In recent years, electrical signals have been adapted to be transmitted at high speed (high frequency) to a control-purpose printed circuit board having electronic parts, ICs (Integrated Circuits) and the like contained in an automotive electrical equipment such as a car navigation system. In addition, circuit patterns on such a printed circuit board have been densely arranged to provide a high-density design. Generally, a coaxial cable is used for transmitting such a high-frequency electrical signal and with the higher-frequency transmission of the electrical signal, the connector for connection to this coaxial cable has been required to have a compact design meeting with the high-frequency transmission.
Referring to a common structure of a coaxial cable, the coaxial cable has a coaxial structure in which an insulator is interposed between a signal conductor (serving as a transmission path for an electrical signal or the like) including a plurality of metal wires twisted together into a bundle and a shielding conductor including a braided wire having a plurality of woven wires. The outer periphery of this structure is covered with an insulating sheath. The shielding conductor covers the outer peripheral surface of the signal conductor with a predetermined gap therebetween completely over the entire periphery thereof, so that this structure is suited for transmitting a high-frequency electrical signal.
Generally, a coaxial connector, which contains terminals and is connected to each of both ends of such a coaxial cable for transmitting a high-frequency signal, includes an inner conductor terminal, an outer conductor terminal, and a dielectric member. The inner conductor terminal is connected to the signal conductor of the cable. The outer conductor terminal is connected to the shielding conductor such as a braided wire and covers the outer periphery of the inner conductor terminal to electromagnetically shield the inner conductor terminal. The dielectric member having a predetermined dielectric constant is interposed between the inner conductor terminal and the outer conductor terminal. The inner conductor terminal and the outer conductor terminal are electrically connected separately respectively to the signal conductor and the shielding conductor, which are exposed at the cable end to be connected to the connector by removing the sheath and the insulator therefrom.
When the characteristic impedance of a coaxial cable for transmitting a high-frequency electrical signal does not coincide with the characteristic impedance of each of coaxial connectors connected to both ends of this cable, respectively, the reflection of the signal occurs. This reflection causes noises and besides the transfer of energy is wasted. Therefore, it is necessary to achieve the impedance matching between the coaxial connector and the coaxial cable usually by setting the impedance value, for example, to 50&OHgr;. With respect to the characteristic impedance of the coaxial connector, generally, “a ratio of an inner diameter of a cross-section of the outer conductor terminal to an outer diameter of a cross-section of the inner conductor terminal” and “the dielectric constant of the dielectric member” are adjusted to achieve the impedance matching with a coaxial cable to be connected to the coaxial connector. If the inner conductor terminal within the coaxial connector has any portion, which is not covered with the outer conductor terminal, there is encountered a problem that the shielding performance such as radiation characteristics is lowered. Therefore, it is preferred that the inner conductor terminal should be covered with the outer conductor terminal completely over the entire periphery thereof.
One high-frequency coaxial connector is disclosed in JP-A-2000-260540. This connector is so designed that at a time of mounting the connector on the coaxial cable to connect the connector, cutting of the signal conductor of the coaxial cable and an eccentric arrangement of the inner conductor terminal of the connector with respect to the coaxial cable are prevented.
A process of mounting this coaxial connector on the coaxial cable includes the following steps: i) exposing the signal conductor and a shielding conductor over a predetermined length by peeling a sheath from an end portion of the coaxial cable; ii) press-fastening a press-clamping portion of the inner conductor terminal to the signal conductor; iii) inserting a separately-prepared sleeve between an insulator and the shielding conductor; iv) fitting an outer conductor terminal to the coaxial cable and attaching a dielectric member to the inner conductor terminal; v) subsequently returning the fitted outer conductor terminal to cause this outer conductor terminal to receive the dielectric member therein; and vi) finally press-fastening a press-clamping portion of the outer conductor terminal to the cable.
However, in the coaxial connector disclosed in the JP-A-2000-260540, an opening portion in a rear end of the outer conductor terminal is made large in order to prevent the signal conductor from being cut when returning the outer conductor terminal to cause it to receive the dielectric member attached to the inner conductor terminal. Therefore, the impedance matching with the coaxial cable and the shielding performance were not excellent.
Furthermore, the connector of this structure has a problem with the manner of mounting the connector on the cable. Namely, most of the above mounting steps must be carried out manually and the ratio of its production cost to its product price is higher as compared with those connectors mounted on the cable by a highly-automated process. Therefore it has been difficult to provide this connector at low costs.
SUMMARY OF THE INVENTION
An object of this invention is to provide a coaxial connector in which the impedance matching in the coaxial connector is achieved to reduce the noise radiation amount, the reflection loss of a signal and the like, and a process of mounting the connector on a cable end can be carried out efficiently.
To solve the above problems, there is provided a coaxial connector for a coaxial cable having a signal conductor, a shielding conductor, an insulator disposed between the signal conductor and the shielding conductor, and a sheath covering an outer periphery thereof. The coaxial connector includes an inner conductor terminal, a dielectric member, an outer conductor terminal, and a shielding member. The inner conductor terminal is connected to the signal conductor. The outer conductor terminal of a cylinder shape, receives the inner conductor terminal through the dielectric member. The outer conductor terminal is connected to the shielding conductor. The outer conductor terminal includes a first opening, a side wall, and a convex wall. The convex wall is formed at a position opposed to a connection portion between the exposed signal conductor and the inner conductor terminal, to project toward inside thereof. The shielding member is attached to the outer conductor terminal to close the first opening.
A sectional area of the first opening closed by the shielding member may be smaller than that of other portion of the outer conductor terminal.
The convex wall may be formed to reduce a sectional area of the first opening.
In the coaxial connector of the above construction, the cross-sectional area of the outer conductor terminal at a connecting portion where the signal conductor of the coaxial cable and the inner cond
Autonetworks Technologies Ltd.
Dinh Phuong
Feild Lynn
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