JPS63259914A - Shield 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 (Field of Industrial Application) The present invention relates to a shielded cable, and particularly to a shielded cable with good characteristics that does not reduce the shielding effect even at high frequencies.

(Prior Art and its Problems) Conventionally, as this type of shielded cable, cables in which copper braid, copper tape, or the like is used as a shield layer have been mainly used to shield noise generated inside the cable.

Figure 2 shows a coaxial cable that is an example of a conventional shielded cable, and the shield layer, that is, the outer conductive layer,
Copper braid and copper tape are the most commonly used.

However, (a) the manufacturing method of the copper braided shield is very complicated. (b) There were problems such as the weight of the product becoming very heavy.

Furthermore, at high frequencies, the gaps between the braids cannot be ignored, resulting in poor shielding effectiveness.

Incidentally, the copper tape also had the above-mentioned problems (a) and (b).

The present invention aims to solve the problems with conventional copper braided shields and the like, and to provide a shielded cable with good characteristics that does not reduce the shielding effect even at high frequencies.

(Means for Solving the Problems) The shielded cable according to the present invention is a first example product.
As shown in the figure, a shield layer 4 made of carbon fiber, carbon black, and rubber/plastic is provided on an insulator layer 2 of the shield cable. 4
is a rubber compound containing short carbon fibers and carbon black.
It is preferable to use a plastic mixture, or a rubber-plastic mixture containing long carbon fiber yarn and carbon black.

In one embodiment, the shield layer 4 is formed by longitudinally splicing or winding a long carbon fiber yarn on the cable insulator layer 2 to form a carbon fiber layer, and on the carbon fiber layer, carbon black is applied. It is also possible to construct the carbon fiber layer by extrusion coating a rubber-plastic mixture containing the above and integrating it with the carbon fiber layer.

FIG. 1 shows a schematic diagram of the structure of a coaxial cable as an embodiment of the shielded cable of the present invention.

The feature of the present invention lies in the shield layer 4;
~30 parts by weight of carbon fibers, preferably carbon fibers consisting of short carbon fibers or long carbon fiber yarns, 5 to 60 parts by weight of carbon black including carbon black, and 100 parts by weight of rubber/plastic. It is.

In the present invention, the reason why carbon fiber is limited to 5 to 30 parts by weight is that if it is less than 5 parts by weight, the desired shielding performance cannot be obtained even when used in combination with carbon black, and if it exceeds 30 parts by weight, molding This is because the performance is lowered and the price increases.

The reason why carbon black was limited to 5 to 60 parts by weight was as follows.
This is because if the amount is less than 5 parts by weight, the performance of the carbon fiber cannot be brought out and the desired electromagnetic shielding performance cannot be obtained. This is because if the amount exceeds 60 parts by weight, the molding processability will deteriorate.

As the rubber/plastic material in the present invention, polyolefins such as polyethylene, polypropylene, ethylene vinyl acetate copolymer, etc., polyvinyl chloride, ethylene propylene rubber, etc. are used.

(Example) Next, examples of the present invention will be described.

Example 1 After covering a 3.4 mm thick polyethylene insulating layer 2 on a conductor 1 with a diameter of 2.9+++ mφ, a polyethylene conductive layer consisting of 15 parts by weight of short carbon fibers, 20 parts by weight of carbon black, and 100 parts by weight of polyethylene was coated. 1,
After forming the carbon fiber-containing conductive shield layer 4 by extrusion coating to a thickness of Qmm, a polyvinyl chloride sheath 5 of 2mm thickness is formed.
The coaxial cable was completed by coating the

Example 2 After covering the conductor 1 with a diameter of 6.3 mmφ with a polyethylene insulating layer 2 having a thickness of 3.7+ nm, long carbon fiber yarns were longitudinally attached, and the conductive mixture containing carbon black in Example 1 was further applied. The material is extrusion coated with long carbon fibers arranged in the conductive mixture layer to form a 1.2 mm thick shield layer 4.
form. Thereafter, a coaxial cable was completed by covering it with a polyvinyl chloride sheath 5 having a thickness of 2.Q mm.

Comparative Example 1 A coaxial cable having substantially the same configuration as Example 1 was prepared except that the shield layer in Example 1 was replaced with shield layer 3 using the same braid.

Regarding Examples 1 and 2 and Comparative Example 1, 5 Q l,
(The shielding effects at Hz were as follows.

In comparative example ■, it is 40 dB.

In Example 1, it was 45 dB.

In Example 2, it is 50 dB.

Both the examples and the examples were better than the comparative examples.

(effect) The effects of the present invention are as follows.

(1) The weight of the cable can be reduced.

(2) The method of manufacturing the cable, including the shielding, becomes simpler and the manufacturing cost can be reduced.

(3) It has sufficient shielding effect even in the high frequency fatigue region.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing the main parts of an embodiment of the present invention, and FIG. 2 is a schematic perspective view showing the main parts of an example of a conventional shielded cable. 1... Internal conductor 2... Insulator layer 3...
Copper braided shield layer 4... Carbon fiber-containing conductive shield layer 5... Sheath Patent applicant Furukawa Electric Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1. A shielded cable comprising a shielding layer made of carbon fiber, carbon black, and rubber/plastic. 2. The shielded cable according to claim 1, wherein the shield layer is made of a rubber-plastic mixture containing short carbon fibers and carbon black. 3. The shielded cable according to claim 1, wherein the shield layer is made of a long carbon fiber yarn and a rubber/plastic mixture blended with carbon black.