JPH0436501Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a signal transmission cable having a center conductor and a shielding outer conductor, and particularly to the structure of its insulating core.

(Prior art) There are various cables such as coaxial cables as low-loss high frequency cables used for transmitting audio signals, video signals, etc. Of these, coaxial cables in particular have an outer conductor formed around a central conductor. acts as a shield, making it extremely suitable for high frequency transmission. In recent years, with the spread of home video cassette players, the interconnection of audio/video equipment such as video tape recorders, video disc players, and system televisions has become more diverse, and the need for superior transmission characteristics to prevent deterioration of sound and picture quality has increased. There is a demand for high quality coaxial cables with

Conventionally, there has been a cable of this type as shown in FIG. The configuration will be explained below using figures.

FIG. 2 is an exploded perspective view of a coaxial cable showing an example of the configuration of a conventional cable.

In the figure, a center conductor 2 is provided near the center of a coaxial cable 1;
An insulating core 3, an outer conductor 4, and an outer sheath 5 are formed so as to be sequentially wrapped in a concentric cylindrical shape.

The center conductor 2 is made of a single or stranded copper wire, and is used to transmit high-frequency signals.In order to minimize transmission loss, the center conductor 2 has a lower oxygen content than conventional annealed copper wire, which hinders signal transmission. Oxygen-free copper conductors (OFC), which have significantly reduced oxidation, are also used.

The insulating core 3 formed around the center conductor 2 is
It provides insulation between the center conductor 2 and the outer conductor 4, and its material is made of polymeric synthetic resin such as polyvinyl chloride or hard polyethylene. As the frequency increases, the dielectric loss of polyvinyl chloride increases and its effectiveness as an insulator decreases.
Hard polyethylene is often used. Furthermore, in order to reduce dielectric loss, attempts have been made to use foamed polyethylene to which a foaming agent has been added.

An outer conductor 4 made of braided thin annealed copper wire or OFC wire for shielding is formed around the insulating core 3, and an outer sheath 5 for covering is further formed around the outer conductor 4. .

(Problems to be solved by the invention) However, the cable with the above configuration has the following problems.

(1) Various attempts have been made to reduce dielectric loss as described above, but conventional insulated cores 3 do not necessarily have sufficient insulation to be used as high-quality connection cables that prevent deterioration of sound quality, picture quality, etc. not enough.

(2) For example, in cables that are likely to be bent during use, such as connection cables for high-precision microphones, the contact surface between the insulating core 3 made of polymer synthetic resin and the outer conductor 4 is Therefore, static electricity is likely to be generated, and during a transient period when the generated static electricity flows out to the outer conductor 4 side, there is a possibility that it may have an adverse effect on the center conductor 2 side as noise. Particularly, such noise has been a big problem in audio equipment and the like because it causes deterioration in sound quality.

The present invention provides a cable that solves the problems of the prior art, such as insufficient insulation and the tendency to generate noise due to the generation of static electricity.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a center conductor for signal transmission, an insulating core for insulation formed around the center conductor, and an insulating core. In the cable, the cable includes an outer conductor for shielding formed around the outer conductor, and an outer sheath for covering formed around the outer conductor, the insulating core being in close contact with the insulating core, A protective layer containing ceramic powder having static electricity resistance and flexibility is formed.

(Function) According to the present invention, since the cable is configured as described above, the protective layer containing ceramic powder formed around the insulating core in close contact with the insulating core has high insulating properties, so that the protective layer It works to supplement the insulation properties of the metal and significantly improve the insulation properties as a whole. When the cable is bent, its high flexibility and adhesion prevent friction from occurring on the contact surface between the insulating core and the external conductor, and work to prevent the generation of static electricity. Furthermore, even if static electricity is generated, the protective layer serves to prevent the influence from spreading to the center conductor. Therefore, the above problem can be solved.

(Embodiment) FIG. 1 is an exploded perspective view of a cable showing a first embodiment of the present invention.

This cable is a low-loss high-frequency coaxial cable 11, and has a concentric cylindrical insulating core 13 formed around a central conductor 12 made of a single or stranded copper wire. A protective layer 1 is provided around the insulating core 13.
4 is formed, and around this protective layer 14 is formed an outer conductor 15 made of a braided copper wire for a central conductor shield, and further around it is an outer sheath made of polyvinyl chloride or the like for covering. 16
is formed.

The insulating core 13 provides insulation between the center conductor 12 and the outer conductor 15, and is made of a polymeric synthetic resin such as polyvinyl chloride or hard polyethylene. The protective layer 14 formed in close contact with the surface of the insulating core 13 is made of a ceramic layer. It is formed by coating 13. The ceramic layer can also be formed by wrapping a polymer film or the like on which ceramic powder has been applied or vapor-deposited in advance around the insulating core 13 and adhering it.

The coaxial cable 11 configured as above is
Since the ceramic protective layer 14 having high insulation properties is formed on the insulating core 13, the center conductor 12 and the outer conductor 15 are reliably insulated. In addition, the protective layer 14, which has a high surface roughness and flexibility, prevents friction caused by peeling at the contact surface between the insulating core 13 and the outer conductor 15 even when the coaxial cable 11 is bent, and prevents static electricity. This has the advantage of preventing the occurrence of Further, even if static electricity is generated, the protective layer 14 also has a shielding effect on the center conductor 14 during a transition period when the static electricity flows out to the outer conductor 15 side.

FIG. 3 is a sectional view of a cable showing a second embodiment of the present invention.

This embodiment differs from the first embodiment in that a protective layer 23 made of the ceramic layer is formed around each insulating core 22 of the two central conductors 21. Between the protective layer 23 and the outer conductor 24, an insulating layer 25 made of insulating intervening yarn or the like is formed for shaping or the like.

With such a configuration, the two center conductors 21
A cable having substantially the same functions and effects as the first embodiment can be obtained, and also has the advantage that mutual interference of high frequency signals between the two center conductors 21 can be prevented.

FIG. 4 is a sectional view of a cable showing a third embodiment of the present invention.

The difference between this embodiment and the second embodiment is that two central conductors 31 separated by an appropriate gap are wrapped in an integral insulating core 32, and this integral insulating core 32 is made of the ceramic layer. Protective layer 3
3 was formed.

This configuration has the advantage that it has substantially the same functions and effects as the second embodiment, and that the structure of the cable is simplified, making it easier to manufacture.

Note that the present invention is not limited to the illustrated embodiment;
Various modifications are possible, including the following modifications.

The structure, shape, material, etc. of the first to third embodiments are not limited, and for example, the center conductor 1221, 31
The present invention can also be applied to cables with three or more cables. In addition, insulating cores 13, 2
2 and 32 can also be formed of materials other than polymer synthetic resin.

In the first to third embodiments, the protective layer 1
The method for forming the ceramic layers 4, 23, and 33 is not limited to the method shown in this embodiment, but it is also possible to form them, for example, by directly spraying ceramic powder onto the surfaces of the insulating cores 13, 22, and 32.

An insulating layer, for example a ceramic layer, can also be interposed between the outer conductors 15, 24 and the outer sheath 16.

(Effects of the invention) As explained in detail above, according to the invention, a protective layer containing ceramic powder is formed around the insulating core in close contact with the insulating core, so that the insulation between the center conductor and the outer conductor is improved. It is possible to significantly increase the signal transmission rate and prevent deterioration of sound quality, image quality, etc. during signal transmission. In addition, the protective layer has the large surface roughness, flexibility, and high flexibility of ceramic powder, so even if the cable is bent during use, the protective layer has high flexibility and adhesion. Prevents friction caused by peeling at the contact surface between the insulating core and the outer conductor, and prevents the generation of static electricity. Further, even if static electricity is generated, the shielding effect of the protective layer prevents the influence of static electricity from spreading to the center conductor, thereby preventing the generation of noise and the like.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of a cable showing the first embodiment of the present invention, Fig. 2 is an exploded perspective view showing an example of the configuration of a conventional cable, and Fig. 3 is an exploded perspective view of a cable showing the first embodiment of the invention. FIG. 4 is a cross-sectional view of a cable showing a third embodiment of the present invention. 11... Coaxial cable, 12, 21, 31...
Center conductor, 13, 22, 32... Insulated core, 1
4, 23, 33... protective layer, 15, 24... outer conductor, 16... outer sheath.

Claims (1)

[Claims for Utility Model Registration] 1. A center conductor for signal transmission, an insulating core for insulation formed around the center conductor, an outer conductor for shielding formed around the insulating core, and In a cable including an outer sheath for covering formed around an outer conductor, a protective layer containing ceramic powder around the insulating core and closely adhering to the insulating core has insulating properties, static electricity resistance, and flexibility. A cable characterized by forming. 2. The cable according to claim 1, wherein the protective layer comprises a layer of ceramic powder applied to the insulating core with an insulating adhesive. 3. The cable according to claim 1, wherein the protective layer is made of a polymer film on which a ceramic layer is formed.