JPH02142019A - coaxial multicore cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in coaxial multicore cables.

[Prior Art] FIG. 5 shows an example of the configuration of a conventional coaxial multicore cable. As is clear from this figure, each wire core a is connected in a ribbon shape, and each wire core a has an inner conductor 1. Insulator 2. Outer conductor 3. It consists of 4 jackets. According to the coaxial multicore cable with the above structure, cables with various characteristic impedances can be obtained, but on the other hand,
The plurality of external conductors 3 must be grounded for each core, which has the disadvantage of complicating terminal processing.

Moreover, FIG. 6 shows the structure of a conventional coaxial cable that has a usage pattern similar to that of a coaxial cable.

5 is a conductor, 6 is a shield plate, and 7 is a jacket. In this case, multiple conductors 5 are used alternately for signal and ground purposes, and the grounding itself is relatively easy, or the terminal processing that is the pre-process is also complicated. There is a drawback.

[:5'i5Clearly the problem to be solved] In order to eliminate these drawbacks, the outer conductors of each core, which has an inner conductor and an outer conductor, are short-circuited through an insulator, and the ground wire is It is proposed to bond an embedded conductive plastic to the external conductor in a short-circuited manner. (Refer to Japanese Utility Model Application No. 53-107986.) This significantly improves operational disadvantages.

However, when a polyvinyl chloride composition mixed with carbon was used as the conductive plastic, the shielding effect was insufficient or remained unsatisfactory. In other words, it has a drawback in electrical characteristics.

The present invention has been made in view of these points, and an object of the present invention is to provide a coaxial multicore cable that has excellent electrical characteristics and can be easily terminal-treated when grounding.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 is a sectional view showing the structure of a coaxial multi-core cable according to an embodiment of the present invention, in which each wire core a is joined in a ribbon shape, and each inner conductor 1. It is composed of an insulator 2 and an outer conductor 3. The ground wire 9 is made of conductive plastic 8 with a central conductor 1' embedded therein, and the outer conductors 3, 3, . ... are connected in a row in a short-circuited state. In addition, in order to join the external conductor 3 and the conductive plastic 8, it is sufficient to bond them with conductive paint, for example.

Therefore, in the coaxial cable having the above structure, in order to ground the ground wire 9 buried in the conductive plastic 8, the outer conductors 3, 3°, etc. of the plurality of wire cores a can be grounded together. This can greatly improve the efficiency of terminal processing.

Also, conductive plastic 8 is used as a covering material for the ground wire 9.
By using a wire stripper, the terminals can be processed very easily with a wire stripper, and the connection between the conductive plastic 8 and the external conductor 3 can be easily performed in many cases by adhesion with conductive paint.

However, in the coaxial multicore cable described above, if a conductive plastic material is also used for the outer conductor 3 of each wire core a, the thickness of the outer conductor 3 and the pitch of each conductor 3uJ'l can be adjusted without changing the characteristic impedance. Since it is easy to align the ground wire 9 and the internal conductor l of each wire core a at the same height h, it is possible to use a one-touch connector.

In this way, it is very advantageous to use a conductive plastic material for the outer conductor 3, or if the DC resistance or shielding effect of the outer conductor 3 is a problem, it is better to use a metal tape for the outer conductor 3. , a large amount of work is required to align each conductor to a specified pitch. Therefore, in order to solve this problem, it is preferable to further coat the outer periphery of a metal tape wound or stretched vertically with a conductive plastic material.

FIG. 2 is a sectional view showing the structure of a coaxial cable according to another embodiment of the invention. That is, each wire core a and the ground wire 9
A jacket 10 is provided around the periphery.

Therefore, this coaxial multicore cable is often used in cases where there is a problem in use if the external conductor 3 is exposed, or where the material of the external conductor 3 is difficult to adhere to with paint. It is something.

Now, the conductive plastic of the coaxial multicore cable of the present invention is formed by mixing nickel powder. Average particle size 2~1gm and specific surface area 0.3~0.8
15 to 40% by volume of nickel powder produced by the carbonyl method with a weight of 7 g.

And a particle size range of 2-7 pm is preferred. Average particle size 2
If the average particle size is less than 7 μm, it is difficult to produce nickel powder, and if the average particle size is 7 μm or more, it is disadvantageous for imparting conductivity to the composition. Preferably, the average particle size is 2 to 31 Lm. The specific surface area of nickel powder is a value measured by the BET method. 0.3-0.8m27g indicates that the nickel powder has an uneven surface rather than a smooth spherical surface, and it is preferable that the balata particles have a connected shape to some extent, such as filament-like ones. . This or 0.
If it is less than 3 m2/g, it is disadvantageous for imparting conductivity, and if it is less than 0.8 m
``More than 7g is a limitation due to the difficulty in manufacturing the powder.This nickel powder minimizes surface oxidation,
In order to obtain a composition with high conductivity, it is preferable to manufacture by the carbonyl method. The amount of nickel powder mixed is
It is necessary to add 15% by volume or more to provide a shielding effect and conductivity. Further, if the content exceeds 45% by volume, the processability of the composition becomes extremely difficult, so it must be avoided.

Preferably it is 25 to 40% by volume. The preferred amount of nickel powder to be mixed is 250 to 600 parts by weight per 100 parts by weight of boria.

Next, the electrical characteristics will be explained in more detail by comparing Examples and Comparative Examples.

The conductive plastic of the example can be obtained, for example, by the following method. That is, polyethylene (manufactured by Ube Industries, Ltd. F-322, melt index MI = 3.' pE degree d = 0.922
) 100 parts by weight of nickel powder (parakeet type 25
5. By using nickel powder such as 430 (average particle size 2.5 gm) mixed with a test roll, conductive plastic has high conductivity and high shielding effect, and has excellent moldability. It was found to be an excellent composition. It has been found that this allows the electrical characteristics of coaxial multi-core cables to be significantly improved.

As shown in FIG. 3, the conductive plastic 8 of the ground wire 9 is made of the above-mentioned nickel-mixed comparan 1- (body resistivity 7xlO-''Ω-cm), and the insulator 2 on the coaxial cable side is made of polyvinyl chloride. coat the inner conductor l,
On top of this, an aluminum mylar tape 3 was placed vertically along the circumference of the conductive plastic 8 on the ground wire 9 side in a spectacle-like manner, and the circumference 8F was further sheathed with polyvinyl chloride lO to form a sample. The inner conductors 1 and 1' were tin-plated copper wires with a diameter of 0.5 mm, and each had an outer diameter of 1.0 mrnφ after being coated with an insulating layer 2 of polyvinyl chloride and a conductive plastic layer 8.

In addition, when the resistance of the surface of the bamboo wire coated with the conductive plastic layer 8 was measured using a tester at 1 cm intervals, it showed a value of 1.5Ω.

The shielding effect was measured using the apparatus shown in FIG.

That is, the copper pipe 11 is arranged parallel to the center conductor 1 of the cable having the structure shown in Fig. s3 and the inner conductor 1' of the ground wire 9. One end of the center conductor l is grounded, and one end of the center conductor l' of the ground M19 is grounded via the voltmeter 12. Further, the shielding effect is measured by applying radio waves of I MHz and 2 MHz to the copper vibrator 11 from a generator 13 of a network analyzer (manufactured by Hewlett-Parakart).

Note that the reference numeral 14 is a voltmeter installed in parallel with the generator 13.

In the cables of the example, large shielding effects of 76 db and 63 db were obtained, respectively.

Comparative Example As the conductive plastic 8 of the above example, conductive polyvinyl chloride (RIKEN VINYL) mixed with carbon black was used.
Co., Ltd. product 5P-7131 body resistivity 2Ω-cm
), an electric wire having the structure shown in FIG. 3 was prepared as a sample in the same manner as in the above example.

The resistance at 1 cm intervals on the surface of the conductive polysalt 1-hibinyl coated wire was 350Ω. Further, the shielding effects of IMH and 2MH2 were 59 db and 44 db, respectively, and the shielding effects were small.

In addition to polyethylene, the conductive composition containing nickel powder may also contain polyvinyl chloride, polyvinyl butyral,
Polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetate, polyvinyl formal, polyvinyl dichloride, chlorinated polyether, polystyrene, styrene-acrylonitrile copolymer, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene , ultra-low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polypropylene, polyacetal, polymethyl methacrylate, and various polyimide resins.

Various cellulose, polycarbonate, phenoxy, polyester, trifluorochloroethylene resin.

Tetrafluoroethylene-hexafluoropropylene resin.

Vinylidene fluoride resin, polyurethane resin, polybutene-1, ionomer resin, epoxy resin.

Polyamide resin or the like may also be used.

Furthermore, other additives and fillers may be added.

Additionally, rubber may be used as the base material. Furthermore, properties can be improved by crosslinking.

[Effects of the Invention] As explained above, the coaxial multicore cable of the present invention has the following effects:
Terminal processing is simple and products with excellent electrical characteristics can be manufactured.

[Brief explanation of the drawing]

FIGS. 1, 2 and 3 show examples of embodiments of the invention.
FIG. 4 is a cross-sectional view showing the configuration of a coaxial multi-core cable, and a circuit diagram of a measuring device that measured the shielding effect. FIGS. 5 and 6 are cross-sectional views of a conventional coaxial multicore cable and a multicore cable that is used in a manner similar to that of the coaxial cable.

Claims (1)

[Claims] 1. Connecting the outer conductors of each core having an inner conductor and an outer conductor via an insulator in a short-circuited state, and
A coaxial multicore cable comprising a conductive plastic with a ground wire buried therein and short-circuited to the external conductor, characterized in that the conductive plastic is a composition mixed with nickel. 2. The coaxial multicore cable according to claim 1, wherein the conductive plastic has a volume resistivity of 1 Ω-cm or less.