Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
2000-07-06
2002-07-09
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S028000
Reexamination Certificate
active
06417445
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an elementary coaxial cable wire, and a coaxial cable and a coaxial cable bundle using the above elementary coaxial cable wire.
2. Description of Related Art
It is known that wire cables used for signal transmission in medical equipment such as a diagnostic probe in a ultrasonic diagnostic apparatus, and an endoscope, as well as in an industrial robot; and wire cables used for internal connection in information equipment such as a notebook-sized personal computer are repeatedly bent during use. This causes strain to be accumulated in the wire cable and there is a possibility that a break in the wire cable may occur.
Accordingly, in order to increase bending resistance of the wire cable, a stranded wire formed by twisting a number of thin wires together is broadly employed as the core conductor of a coaxial cable (or an elementary coaxial cable wire thereof), i.e., as the wire cable. One example of such a coaxial cable is shown in Japanese Laid-Open Patent Publication No. 9-35541, in which a wire made of conductive fiber reinforced copper matrix complex and a cable formed by this wire are disclosed.
SUMMARY OF THE INVENTION
The inventors in the present application have applied themselves closely to the study of the above prior art wire and cable using such a wire. As a result, they have found that the prior art involves the following drawbacks, that is:
(1) Although the prior coaxial cable using a stranded wire as a core conductor thereof has good flexibility, the configuration of the stranded wire formed by twisting thin wires together may collapse or loosen when crimped or pressed. Thus, a break in the core conductor may occur when the coaxial cable is in service;
(2) When the end of the core conductor is soldered to a circuit board having a pattern of fine-pitch traces, short circuits may be possibly caused, as the thin wires come undone due to the loosening of the stranded wire. Thus, the connection and successive processing of the coaxial cable end, including inspection of manufactured coaxial cables, become very complicated; and
(3) Furthermore, the stranded wire not only involves the above disadvantages, but also requires much expense in time and effort to manufacture the same. Thus, it has been desired to provide a coaxial cable not only having good flexibility, but also capable of decreasing manufacturing and connecting costs.
The present invention has been made in view of the above circumstances and has for its object to provide an elementary coaxial cable wire, a coaxial cable, and a coaxial cable bundle, each of which has a sufficient bending resistance, can effectively prevent a break or a short circuit in the connection, and can achieve greater economy.
The inventors have repeated diligent studies and, as a result, have found that there is a close correlation between a tensile strength and material of a core conductor, and a bending resistance of a wire. The present invention has been invented based on the above finding.
According to one aspect of the invention, an elementary coaxial cable wire comprising a core conductor, an insulator surrounding the core conductor, and an outer conductor surrounding the insulator is provided. The elementary coaxial cable wire is characterized in that the core conductor is made of a metallic material including copper and silver so as to have a tensile strength of 120 kgf/mm
2
(kg/mm
2
) or more and an electrical conductivity of 60 to 90% by IACS (International Annealed Copper Standard).
Although a high bending resistance is required to elementary coaxial cable wires and coaxial cables used for the above-described applications, the prior art solid single wire consisting of the copper-containing metallic material could not exhibit the required bending resistance, resulting in a relatively short bending life (the number of bending times until fracture may be small). However, it has been determined that the elementary coaxial cable wire being constructed as above-explained according to the present invention has a very extended life despite the solid single wire employed as the core conductor. Generally, the fatigue limit increases with the tensile strength and this is substantially applicable to the bending characteristics. The more the tensile strength increases, the more the bending characteristics become superior.
Preferably, the core conductor has a plastic elongation of L in %, which meets the requirements expressed by the following equation (1):
0.2%≦L≦2.0% (1)
Bending tests were conducted on coaxial cables using conductors as a core conductor having the same tensile strength of 120 kgf/mm
2
or more but different in plastic elongation. As a result, it has been shown that the coaxial cables using the core conductors, of which plastic elongation falls within the range expressed in the equation (1), have bending life longer than that of the coaxial cables using the core conductors, of which plastic elongation is below the lower limit in that range. Thus, in point of the bending characteristics, the coaxial cables according to the present invention are far superior to the prior art cable.
This tendency is more notable in the coaxial cable according to the present invention, in which the core conductor comprises the solid single wire, as compared to the prior coaxial cable including the core conductor composed of the stranded wire. It is considered that in the bending tests, a strain larger than plastic elongation is created in the surface of a core conductor and with the specific configuration of a coaxial cable, plastic elongation of the core conductor according to the present invention becomes larger than the prior art. Therefore, it is expected that under the above conditions, the occurrence of a crack and the propagation thereof in a surface portion of the core conductor which is subject to the largest strain is more restricted in the core conductor forming the elementary coaxial cable wire according to the present invention.
It is also noted that as the core conductor is composed of a solid single wire, the configuration of the core conductor will not be easily collapsed when it is forcedly pressed at connectorizing process. Thus, a break in the core conductor is prevented from occurring when the elementary coaxial cable wire is in service. Furthermore, when the core conductor is soldered to a circuit board having a pattern of fine-pitch traces, the core conductor does not become loose, so that occurrence of short circuits can be effectively prevented. Thus, not only the load of inspection during the connection is significantly lightened, but also the number of man-hours needed to perform the connection and successive processing for the elementary coaxial cable wire can be surprisingly diminished.
Furthermore, as the core conductor is a solid single wire, the core conductor can be deformed so as to have a uniform cross section when the terminal end of the elementary coaxial cable wire is swaged by a press and so on, provided that pressure conditions and so on are maintained constant. Thus, it is possible to surely connect a plurality of elementary coaxial cable wires, as a single unit, to the corresponding connecting points on such as a substrate. In other words, the elementary coaxial cable wires can be easily connected, so to speak, in a manner similar to that in which an integrated circuit (IC) is deposited on such a substrate as a circuit board. As a result, the number of man-hours needed to perform the connection and successive processing of the elementary coaxial cable wires can be further surprisingly diminished.
As the conductivity is within the above range, it is possible to prevent increased transmission loss due to Joule heat created within the core conductor. Thus, as the increased loss of transmission due to Joule heat created within the core conductor during the signal transmission can be prevented, it is not necessary to increase the core-conductor diameter in order to restrict the loss of transmission.
Fur
Chiba Yukifumi
Sato Kazuhiro
Yokoi Kiyonori
Mayo III William H.
Reichard Dean A.
Smith , Gambrell & Russell, LLP
Sumitomo Electric Industries Ltd.
LandOfFree
Elementary coaxial cable wire, coaxial cable, and coaxial... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Elementary coaxial cable wire, coaxial cable, and coaxial..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Elementary coaxial cable wire, coaxial cable, and coaxial... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2831768