JP2001143543A - Coaxiail cable with shield - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shield attachment coaxial cable that can excellently remove a noise and accomplish an improvement in reducing diameter, flexibility and handling. SOLUTION: A shield has at least two layers of structure, a first layer of the shield is metal, metal laminate tape or a combination of them, and at least one layer after a second layer is formed by a conductive thermoplasticity resin, and the first and the second resin is electrically isolated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shielded coaxial cable. More specifically, the present invention provides:
TECHNICAL FIELD The present invention relates to a shielded coaxial cable used for signal transmission of electronic devices and computer devices, and more particularly to a shielded coaxial cable which has improved noise removal capability, reduced diameter, improved flexibility and handleability.

[0002]

2. Description of the Related Art In recent years, communication equipment, computer electronic equipment, and general electronic equipment have become faster, smaller, and densely packed, and coaxial cables have been frequently used to transmit high-speed information signals. Especially in computer electronics,
With computer clock frequencies becoming very high, coaxial cables are shielded with braided or wrapped metal wire, or metal-laminated tape to avoid the effects of noise. Shielded coaxial cable is used.

[0003] In recent years, the speed of various devices has been further increasing,
Stricter standards are also set for noise emission and malfunction due to noise, and accordingly, shielded coaxial cables are required to have high noise removal capability.

[0004] Methods for improving the noise removal capability of a shielded coaxial cable include a method of doubling a braided structure in which a metal wire is woven, a method of combining a metal wire and a metal laminate tape in a metal surface, There are various methods such as a method of forming a combined structure in which a conductive resin and a metal wire are brought into contact, a method of coating a metal wire with vinyl chloride or the like, and further applying a metal wire.

FIG. 2 is a sectional view showing a first example of a conventional shielded coaxial cable. 11 is a silver-plated soft copper wire conductor, 12 is a polyethylene foam insulator, 13 is a drain wire, 14 is an aluminum polyester laminated tape, 15
Is a vinyl chloride jacket.

A polyethylene foamed insulator 12 is formed by extruding about 20% of expanded polyethylene around a silver-plated soft copper wire conductor 11 having a diameter of 0.2 mm. The portion composed of the silver-plated soft copper wire conductor 11 and the polyethylene foam insulator 12 is called an insulating core. The diameter of the insulating core is about 0.
65 mm. Then, a drain wire 13 is vertically attached to the insulating core to form an aluminum polyester laminated tape 14.
Is wound so that the metal surface thereof is in contact with the drain wire 13, and the vinyl chloride jacket 15 is coated thereon.
The finished cable outer diameter is about 1.3 mm. To increase the noise removal capability of this shielded coaxial cable,
A combination structure in which the metal surface of the aluminum polyester laminated tape 14 is brought into contact with the drain wire 13 is employed.

FIG. 3 is a sectional view showing a second example of a conventional shielded coaxial cable. 21 is a silver-plated soft copper wire conductor, 22 is a polyethylene foam insulator, 23 is a first silver-plated soft copper wire braid, 24 is a second silver-plated soft copper wire braid, and 25 is a vinyl chloride jacket.

[0008] About 20% around the silver-plated soft copper wire conductor 21
The foamed polyethylene is extrusion coated to form a polyethylene foam insulator 22. The portion composed of the silver-plated soft copper wire conductor 21 and the polyethylene foam insulator 22 is called an insulating core. The diameter of the insulating core is about 0.65 mm.
85% of silver-plated soft copper wire with a diameter of 0.08 mm from above
The above braid is performed twice, and the first silver-plated soft copper wire braid 23
And a second silver-plated soft copper wire braid 24 is formed. And as an exterior, a vinyl chloride jacket 25 is covered, and the cable outer diameter is finished to about 1.85 mm. To increase the noise removal capability of this shielded coaxial cable,
A method is adopted in which a braided structure obtained by braiding silver-plated annealed copper wires is doubled.

[0009]

The conventional shielded coaxial cable has the following problems.

[0010] A method of improving the noise removal capability of the shielded coaxial cable includes a method of doubling a braided structure in which a metal wire is knitted, a method of forming a combined structure in which a metal wire and a metal surface of a metal laminated tape are brought into contact with each other, There are various methods such as a method of forming a combination structure in which conductive resin and metal wire are in contact, and a method of coating metal wire with vinyl chloride etc. and further applying a metal wire. There are problems that the attached coaxial cable becomes hard and has poor flexibility, the finished outer diameter of the cable is large, and the time for processing the terminal becomes long.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shielded coaxial cable which solves the above-mentioned disadvantages of the prior art, has an excellent noise removing capability, and has a reduced diameter, improved flexibility and handleability. It is in.

[0012]

According to the present invention, in order to achieve the above object, the shield structure has at least two or more layers, and the first layer of the shield structure is made of metal or metal laminate tape or a combination thereof. In addition, at least one layer after the second layer of the shield structure is made of a conductive thermoplastic resin.

The first and second layers of the shield structure are electrically separated from each other.

As the conductive thermoplastic resin, any one of conductive vinyl chloride, conductive polyethylene and conductive fluororesin was used.

[0015]

FIG. 1 is a sectional view showing an embodiment of a shielded coaxial cable according to the present invention. 1 is a silver-plated soft copper wire conductor, 2 is a polyethylene foam insulator, 3 is a drain wire, 4 is an aluminum polyester laminated tape,
5 is a polyester tape, and 6 is a conductive vinyl chloride jacket.

A polyethylene foamed about 20% is extruded around a silver-plated soft copper wire conductor 1 having a diameter of 0.2 mm to form a polyethylene foam insulator 2. The portion composed of the silver-plated soft copper wire conductor 1 and the polyethylene foam insulator 2 is called an insulating core. The diameter of the insulating core is about 0.65 mm. A drain wire 3 having a diameter of 0.
An 18 mm silver-plated soft copper wire is added, and the aluminum polyester laminated tape 4 is wound with its metal surface (aluminum surface) in contact with the silver-plated soft copper wire. A polyester tape 5 was wound thereon, and a conductive vinyl chloride jacket 6 was provided as an exterior. Finished cable outer diameter is about 1.3mm
It is.

In order to increase the noise removing capability of the shielded coaxial cable, a two-layer (double) shield structure is used. For the first layer of the shield structure, a combination of the drain wire 3 and the aluminum polyester laminated tape 4 is used. For the second layer of the shield structure, a conductive vinyl chloride jacket 6 which is a conductive thermoplastic resin is used. The first layer and the second layer of the shield structure are electrically separated from each other because the polyester tape 5 is wound between them.

Various characteristics of the shielded coaxial cable shown in the above embodiment were compared with the first and second examples of the conventional shielded coaxial cable. Table 1 shows the results.

[0019]

[Table 1]

The first and second examples refer to the prior art shielded coaxial cables, ie, the shielded coaxial cables of FIGS. 2 and 3. As can be seen from Table 1, the noise elimination ability of the shielded cable with the outer sheath covered with the conductive vinyl chloride jacket 6 (Example) is the same as that of the double shielded product (double braid, second example). Are equivalent,
The finished cable outer diameter was also reduced. Also,
Since a polyester tape 5 is inserted between the inner shield (a portion composed of the drain wire 3 and the aluminum polyester laminated tape 4) and the outer shield (conductive vinyl chloride jacket 6) and is electrically insulated, Thus, a shielded coaxial cable in which the inner shield and the outer shield do not have the same potential was obtained. Accordingly, a shielded coaxial cable having excellent noise removal capability and having a reduced diameter, improved flexibility, and improved handleability has been realized.

The withstand voltage characteristics of the embodiment, the first example and the second example were measured by applying an AC voltage of 500 V between the outer coating (vinyl chloride jacket) and the ground. Did not.

In the embodiment, the drain wire 3 and the aluminum polyester laminated tape 5 are used for the first layer of the shield structure. The material used for the first layer of the shield structure is as follows.
It may or may not be plated with a metal wire, or a combination of a metal wire and a metal laminated tape may be used. The metal laminated tape may be a combination of two or more types of metal, and may or may not be plated.

Further, the conductive thermoplastic resin used for the second and subsequent layers of the shield structure may be any of conductive vinyl chloride, conductive polyethylene, and conductive fluororesin. Then, a metal layer or a metal laminate tape may be further added on the conductive thermoplastic resin after the second layer of the shield structure. Moreover, on the second layer and subsequent conductive thermoplastic resin,
A coating such as vinyl chloride, polyethylene, and fluororesin may be applied.

Although the shape of the shielded coaxial cable is described as being round, it may be round, square, or any other shape.
A plurality of shielded coaxial cables having these shapes may be arranged in a flat shape. Also, after twisting a plurality of cables, the cable exterior may be collectively applied.

[0025]

According to the shielded coaxial cable of the present invention, the shield structure has at least two layers, and the first layer of the shield structure is made of metal or a metal laminated tape or a combination thereof. At least one layer after the second layer is made of a conductive thermoplastic resin, and the first layer and the second layer of the shield structure are configured to be electrically separated from each other. A shielded coaxial cable with improved diameter, improved flexibility, and improved handling has been realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a shielded coaxial cable of the present invention.

FIG. 2 is a sectional view showing a first example of a conventional shielded coaxial cable.

FIG. 3 is a sectional view showing a second example of a conventional shielded coaxial cable.

[Description of Signs] 1 Silver-plated soft copper wire conductor 2 Polyethylene foam insulator 3 Drain wire 4 Aluminum polyester laminate tape 5 Polyester tape 6 Conductive vinyl chloride jacket 11 Silver-plated soft copper wire conductor 12 Polyethylene foam insulator 13 Drain wire 14 Aluminum polyester laminate tape 15 Vinyl chloride jacket 21 Silver-plated soft copper wire conductor 22 Polyethylene foam insulator 23 First silver-plated soft copper wire braid 24 Second silver-plated soft copper wire braid 25 Vinyl chloride jacket

Claims (3)

[Claims] 1. A shielded coaxial cable having at least two layers of a shield structure, wherein the first layer of the shield structure is made of metal or a metal laminated tape or a combination thereof, and A shielded coaxial cable characterized in that at least one of the second and subsequent layers is made of a conductive thermoplastic resin. 2. The shielded coaxial cable according to claim 1, wherein the first layer and the second layer of the shield structure are configured to be electrically separated. 3. The shielded coaxial cable according to claim 1, wherein the conductive thermoplastic resin is any one of conductive vinyl chloride, conductive polyethylene, and conductive fluororesin.