High Frequency Noise Prevention Cable

Abstract

A high frequency noise prevention cable comprising a non-metallic filament coated with a conductive and magnetic coating layer composed of one selected from the group of a magnetic metal, metallic oxide and metallic silicate, which may be employed alone except the metal or in combination, and non-metallic particles dispersed in a binding agent of a high frequency inductive synthetic resin or synthetic rubber; a conductive non-metallic filament having a film of conductive non-metallic particles such as carbon, graphite etc. dispersed in a binding agent of a high frequency inductive synthetic resin or synthetic rubber and of more favorable electric conductivity than the former conductive and magnetic coating layer, said first non-metallic filament being wrapped with said second non-metallic filament; a conductive, magnetic and flexible coating layer composed of one selected from the group of a magnetic metal, metallic oxide and metallic silicate, which may be employed alone except the metal or in combination, and conductive non-metallic particles such as carbon, graphite etc. dispersed in a binding agent of vulcanized rubber, said conductive, magnetic and flexible coating layer being formed around said wrapped non-metallic filament; and a rubber coating having an insulating property and another rubber coating for protection being formed therearound. Such a cable is capable of preventing noises in every range of high frequency and is also capable of attaining a favorable electrical connection with a metallic terminal at the end thereof.

Description

This invention relates to a high frequency noise prevention cable, and more particularly to an improvement in a cable capable of preventing noises in every range of high frequency, and also capable of attaining a favorable electrical connection with a metallic terminal at the end thereof.

The conventional high frequency noise prevention cable is composed of a non-metallic conductor such as a filament simply dipped in colloidal alcoholic carrier of carbon particles to apply the carbon particles to the surface of the filament, a conductive rubber coating is applied thereto to prevent said particles from falling off and to give the filament flexibility, a mesh tissue is provided thereon and a conductive rubber layer further applied thereto on its outermost surface. Accordingly, in the cable thus obtained, when the rubber insulator is peeled off for attaching a metallic terminal to the end of the cable, the carbon particles applied to the surface of the filament easily fall off due to a mechanical stress, thereby causing a substantial reduction of conductivity.

At the same time, a variation of the compression power in pressing the metallic terminal onto the cable causes a variance of contact resistance between the conductor and the metallic terminal, and leads to the generation of corona discharge which invites the high frequency noise contrary to what is desired.

Such corona discharge forms a film of metallic oxide on the surface of the metallic terminal, which causes an unfavorable conductivity between the conductor and the metallic terminal.

The conventional cable of this kind has a further defect that it is effective in preventing the VHF noise, but scarcely any measures are taken to prevent the UHF noise.

The present invention is made to overcome the above described drawbacks through the conventional technique of the field.

Therefore, it is an object of the present invention to provide a high frequency noise prevention cable which can effectively prevent noises in every range of high frequency and can attain a favorable electrical connection with a metallic terminal at the end thereof.

Essentially, according to this invention, there is provided a high frequency noise prevention cable comprising a non-metallic filament coated with a conductive and magnetic coating layer composed of a material selected from the group consisting of a magnetic metal, metallic oxide and metallic silicate, which may be employed alone, except a metal, or in combination, and nonmetallic particles dispersed in a binding agent of a high frequency inductive synthetic resin or synthetic rubber; a conductive non-metallic filament having a film of conductive non-metallic particles such as carbon, graphite etc. dispersed in a binding agent of a high frequency inductive synthetic resin or synthetic rubber and of more favorable electric conductivity than the former conductive and magnetic coating layer, said first non-metallic filament being wrapped with said second non-metallic filament; a conductive, magnetic and flexible coating layer composed of a material selected from the group consisting of a magnetic metal, metallic oxide and metallic silicate, which may be employed alone except a metal or in combination, and conductive non-metallic particles such as carbon, graphite etc. dispersed in a binding agent of vulcanized rubber, said conductive, magnetic and flexible coating layer being formed around said wrapped non-metallic filament; and a rubber coating having an insulating property and another rubber coating for protection being formed therearound, thereby preventing noises in every range of high frequency.

The foregoing and other objects, features and advantages of the present invention will be apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 shows a partly cut away perspective view of a high frequency noise prevention cable according to the present invention;

FIG. 2 shows a longitudinal sectional view of the central portion of said cable.

Referring now to FIGS. 1 and 2, numeral 1 is a non-metallic filament. Numeral 2 is an electrically conductive coating layer composed of one selected from the group of a magnetic metal, metallic oxide and, metallic silicate, which may be employed alone except a metal or in combination, and non-metallic particles having a particle size passable through a sieve of 400 - 450 meshes and dispersed in a binding agent of synthetic resin such as phenol resin, aminoalkyd resin or synthetic rubber such as polychloroprene with high frequency inductive property. The external surface of said electrically conductive layer 2 is further wrapped tightly with a conductive non-metallic filament 3 having a conductive film therearound composed of non-metallic particles such as carbon particles, graphite particles, etc. having the same particle size as above and dispersed in a binding agent of synthetic resin or rubber with high frequency inductive property. There is further applied thereto an electrically conductive, magnetic, and flexible coating layer 4 composed of one selected from the group of magnetic metal, metallic oxide, and silicate, which may be employed alone except a metal or in combination, and carbon particles, graphite particles and or other conductive non-metallic particles having the same range of particle size as above and vulcanized rubber. Numeral 5 designates a rubber insulation coating and numeral 6 a rubber protection coating.

The present invention is further illustrated by the following examples which should not be construed to limit the scope of this invention.

The percentage values in the examples are all by weight if not otherwise specifically indicated.

Example 1

On the surface of 6 bundles of glass fiber ECG No. 150 (diameter size prescribed by Japan Industrial Standards) on the market is formed a layer of coating material consisting of 30 percent of phenol resin, 3 percent of Fe, 5 percent of Fe.sub.2 O.sub.3, 55 percent of Fe.sub.3 0.sub.4, and 7 percent of FeO.sup.. SiO.sub.2 with a particle size passable through a sieve of 430 meshes to obtain a linear conductor with conductivity and magnetism. (D.C. resistance value is 1M.OMEGA. per 100mm.) The external surface of said linear conductor is tightly wrapped at a uniform pitch with a conductive filament formed of a strand of six nylon with a size of 1000 denir, the surface of which is coated with coating material consisting of 40 percent of aminoalkyd resin and 60 percent of carbon particles with a particle size passable through a sieve of 400 meshes (D.C. resistance value of 500.OMEGA.per 100mm). On the further external surface is formed a rubber layer having both conductivity and magnetism consisting of 10 percent of natural rubber, 3 percent of vulcanizing agent, 20 percent of phenol resin, 3 percent of Fe, 4 percent of Fe.sub.2 O.sub.3, 50 percent of Fe.sub.3 O.sub.4, 6 percent of FeO.sup.. Sio.sub.2, and 4 percent of graphite particles with a particle size of 400 meshes and the still further external surface is covered with ordinary rubber.

The thus obtained high frequency noise prevention cable has a DC resistance value of 1.3K.OMEGA. per 100 mm and is immediately magnetized when it comes near the magnetic field and demagnetized the instant the magnetic field is withdrawn.

Said high frequency noise prevention cable is magnetized when a DC is applied to the conductor and is demagnetized immediately after the DC is cut off. It is also magnetized when a high frequency current is applied thereto.

Example 2

1. On the surface of six bundles of glass fiber ECG No. 150 on the market is formed a coating of coating material consisting of 30 percent of phenol resin, 1 percent of Fe, 3 percent of Fe.sub.2 O.sub.3, 60 percent of Fe.sub.3 O.sub.4, 5 percent of FeO.sup.. SiO.sub.2, 0.01 percent of V.sub.2 O.sub.5 and 0.99 percent of carbon particles with a particle size of 400 meshes to obtain a linear conductor with conductivity and magnetism. (DC resistance value is 400K.OMEGA. per 100mm)

2. On the surface of glass fiber ECG No. 450 is formed a coating of coating material consisting of amino-alkyd resin and carbon particles with a particle size of 450 meshes to obtain a conductive filament (DC resistance value is 650.OMEGA. per 100mm).

On the external surface of the linear conductor as above mentioned in (1) is tightly wrapped at a uniform pitch with a conductive filament obtained in above (2). On the further external surface is formed a rubber layer with both conductivity and magnetism consisting of 30 percent of polychloroprene, 3 percent of vulcanizing agent, 4 percent of phenol resin, 3 percent of Fe, 3 percent of Fe.sub.2 O.sub.3, 55 percent of Fe.sub.3 O.sub.4, 1 percent of FeO.sup.. SiO.sub.2 and 1 percent of graphite particles with a particle size of 400 meshes and the still further external surface is covered with ordinary rubber.

The thus obtained high frequency noise prevention cable has a DC resistance value of 1.7K.OMEGA. per 100mm and is immediately magnetized when it comes near the magnetic field. The cable is magnetized when a DC is applied thereto, and demagnetized immediately after the DC is cut off. It is also magnetized when a high frequency current is applied thereto.

According to the present invention, the two conductive magnetic layers formed inside and outside of the wrapped conductive non-metallic filament are magnetized by the magnetic field effected when the current flows in the coil of said conductive non-metallic filament, thereby increasing the reactance of said conductive filament to prevent noises in the high range of high frequency, and noises in the low range of high frequency are prevented by means of DC resistance.

Moreover, according to the present invention, all kinds of particles of the conductive materials are fixed in a coating materials by means of a binding agent so that they do not easily fall off to make the terminal connection unstable.

Claims

1. A cable capable of preventing high frequency noise, comprising: a non-metallic core coated with a first, conductive and magnetic coating layer, said first coating layer consisting essentially of a dispersion, in a high frequency inductive synthetic resin or synthetic rubber, of fine particles of material selected from the group consisting of 1 magnetic metal mixed with metallic oxide or metallic silicate, 2 metallic oxide, 3 metallic silicate, 4 conductive non-metallic particles and 5 mixtures of 1, 2, 3, 4; a conductive non-metallic filament wound around said first coating layer, said filament being coated with a conductive film which is more conductive than said first coating layer, said conductive film consisting essentially of a dispersion, in a high frequency inductive synthetic resin or synthetic rubber, of particles of conductive non-metallic material; a second, conductive magnetic and flexible coating layer applied onto and encircling said filament, said second coating layer consisting essentially of a dispersion in vulcanized rubber of fine particles of material selected from the group consisting of 1 percent a magnetic metal mixed with metallic oxide or metallic silicate, 2 metallic oxide, 3 metallic silicate, 4 percent conductive non-metallic particles and 5 percent mixtures of 1, 2, 3, 4; and rubber coating layer means

2. A cable according to claim 1, in which the particles all have a size in

3. A cable according to claim 1, in which the synthetic resin is selected

4. A cable according to claim 1, in which the synthetic rubber is

5. A cakle according to claim 2, in which the non-metallic particles are selected from the group consisting of carbon and graphite.