JP2000030548A - Low noise coaxial cable and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low noise coaxial cable which can perform a high speed signal transmission, does not damage flexibility, and easily performs a terminal processing. SOLUTION: This cable 10 comprises: an inner conductor 2; a dielectric layer 3 which covers the circumference of inner conductor 2; a plastically deformable semi-conductive layer 4 which is formed around the dielectric layer 3; an outer conductor layer 5 which is formed around the semi-conductive layer 4; and a jacket 6 which is covered around the outer conductor layer 5. The outer conductor layer 5 is inserted into the semi-conductive layer 4 so as to be brought into close contact with the dielectric layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-noise coaxial cable and a method of manufacturing the same, and more particularly to a low-noise coaxial cable having good flexibility and easy terminal processing and a method of manufacturing the same. .

[0002]

2. Description of the Related Art Conventionally, for example, bending between a coaxial cable and mechanical vibration causes sliding between an outer conductor of the coaxial cable and a dielectric material. In some cases, the transmission characteristics of the cable were adversely affected. In order to prevent this adverse effect, a low-noise coaxial cable has been proposed. In this low-noise coaxial cable, a semiconductive layer is provided between an outer conductor layer and a dielectric layer of the coaxial cable, and furthermore, these cables are provided. In order to prevent sliding between the layers, the layers are tightly adhered to each other so that the coaxial cable is inferior in flexibility. The work of removing the semiconductive layer, which is performed during the terminal treatment, is also difficult and time-consuming, and the terminal treatment is troublesome.

[0003] Among the low-noise coaxial cables described above, for example, coaxial cables capable of high-speed signal transmission have been proposed.
As a dielectric covering the inner conductor, polytetrafluoroethylene having a low dielectric constant is used to cover the periphery of the inner conductor, and a semiconductive layer provided between the dielectric and the outer conductor is made of porous polytetrafluoroethylene. Low-noise coaxial cable with a semi-conductive tape wound by mixing conductive carbon powder or carbon fiber into the porous portion of a fluoroethylene tape and then sintering and fusing completely. Therefore, the dielectric material and the tape made semiconductive are firmly adhered to each other. As a result, the flexibility of the cable is poor, and when the cable is subjected to the terminal treatment, the semiconductive material is hardly adhered. It took time to remove the layer from the dielectric using a blade or a cutting tool, and the operation was difficult. In particular, when the diameter of the low-noise coaxial cable is small, there is a problem that it takes a very long time to process the terminal and the operation becomes very difficult.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to enable high-speed signal transmission without impairing flexibility. Another object of the present invention is to provide a low-noise coaxial cable in which terminal processing is easy.

[0005]

The above object is achieved by a low-noise coaxial cable and a method of manufacturing the same according to the present invention. That is, in summary, the present invention provides an inner conductor, a dielectric layer coated around the inner conductor, a plastically deformable semiconductive layer formed around the dielectric layer, In a low-noise coaxial cable having an outer conductor layer formed around a layer and a jacket covered around the outer conductor layer, the outer conductor layer is embedded in the semiconductive layer to form the dielectric layer. A low-noise coaxial cable characterized by being in close contact with a conductor, a step of preparing an inner conductor, a step of coating a dielectric layer around the inner conductor, and a step of providing a dielectric layer. Forming a plastically deformable semiconductive layer around the body layer, forming an external conductor layer around the semiconductive layer, and squeezing the external conductor layer from outside to form the external conductor layer. The external conductor layer and the semiconductor layer are embedded in a semiconductive layer. A step of the conductive layer in close contact with the dielectric layer, the outer conductor layer low noise coax, characterized in that it comprises a step of coating a jacket around the - is a manufacturing method of Bull.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a low-noise coaxial cable 1 according to the present invention, an external conductor layer is squeezed from outside without sintering a semiconductive layer, and this external conductor layer is unfired or semi-fired EPTFE. When embedded in a plastically deformable semiconductive layer for tape making, as a result, the semiconductive layer and the outer conductive layer are brought into close contact with the dielectric layer and are maintained there. By unwinding the semiconductive layer formed by tape winding from the dielectric layer,
It can be easily removed without the need for special tools or equipment, and terminal processing can be performed very easily.
Further, in this low-noise coaxial cable, as described above, the firing for fusing the semiconductive layer to the dielectric layer is not performed, and therefore, the flexibility is not impaired.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described below on the basis of an embodiment with reference to the accompanying drawings. FIG. 1 is a sectional view of one embodiment of a low noise coaxial cable according to the present invention. Referring to FIG. 1, there is shown a low noise coaxial cable 10 according to the present invention.
Is a dielectric layer formed by extruding and coating polytetrafluoroethylene having a low dielectric constant around the inner conductor 2 (in this embodiment, seven stranded silver-plated copper-coated steel wires having an outer diameter of 0.17 mm). 3 (in this embodiment, the outer diameter is 1.3 m).
m).

Around the dielectric layer 3, an unfired or semi-fired semiconductive carbon fiber or carbon fiber is mixed into a porous portion of a porous polytetrafluoroethylene (EPTFE) tape to make it semiconductive. By winding an EPTFE tape (5 mm in width and 0.1 mm in thickness in this embodiment), the semiconductive layer 4 (0.2 mm in thickness in this embodiment) is formed.
mm), and around the semiconductive layer 4, an outer conductor layer 5 (in this embodiment, 43 silver-plated soft copper wires having an outer diameter of 0.12 mm) of a horizontally wound shield in which a conductor element wire is horizontally wound. Used and an outer diameter of 1.84 mm).

Then, using a die (not shown) or the like,
The formed outer conductor layer 5 is squeezed from the outside, and the outer conductor layer 5 is embedded in the plastically deformable semiconductive layer 4 for an unfired or semi-fired EPTFE tape. The layer 4 and the outer conductor layer 5 are adhered to and maintained on the dielectric layer 3, and then the outer conductor layer 5 is further covered with a tetrafluoroethylene-hexafluoropropylene copolymer (FEP). The low-noise coaxial cable 10 is formed by forming the jacket 6 (in this embodiment, the thickness is 0.2 mm).

When the terminal processing is performed in the low noise coaxial cable 10 configured as described above,
After removing the jacket 6 of a desired length from the end of the cable 10, the outer conductor layer 5 embedded in the semiconductive layer 4 is removed from the semiconductive layer 4 and bundled, and then folded in a predetermined direction. By unwinding the semiconductive layer 4 formed by tape winding, the semiconductive layer 4 was pressed against and adhered to the dielectric layer 3 by the embedded external conductor 5.
The semiconductive layer 4 of a so-called green tape, ie, an unfired or unfired EPTFE tape, can be easily removed from the dielectric layer 3 without requiring any special tools or equipment, Terminal processing can be performed very easily.

Further, in the low-noise coaxial cable 10, the semiconductive layer 4 of the unfired or semi-fired EPTFE tape is fixed to the dielectric layer 3 together with the outer conductor layer 5 by ironing from the outside of the outer conductor layer 5. , And is maintained there, so that firing for fusing to the dielectric layer 3 is not performed, and therefore, flexibility is not impaired.

In order to measure the noise charge of the low-noise coaxial cable having the above-described structure according to the present invention, a cable having a length of 2 m was used as a sample, and an amplitude of 5 mm and a frequency of 20 H were used.
When a vibration of z was applied, the noise charge was 7 pC (pico
Coulomb). As a comparative example, when the noise charge amount was measured under the same conditions for a device without the semiconductive layer 4 of the present invention, the noise charge amount was 1000 pC (pico-coulomb). It can be understood that the noise charge amount of the .sigma.

[0013]

As described above, according to the low-noise coaxial cable of the present invention, high-speed signal transmission is possible because polytetrafluoroethylene having a low dielectric constant is used for the dielectric layer and the semiconductive layer. In addition, since the semiconductive layer is not fired into the dielectric layer, the semiconductive layer can be easily removed from the dielectric layer without requiring any special tools or equipment, and the terminal treatment can be performed. This is very easy to perform, and also has the effect of not impairing the flexibility.

[0014]

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a low noise coaxial cable according to the present invention.

[Explanation of symbols]

2: internal conductor, 3: dielectric layer,
4: semiconductive layer, 5: outer conductive layer,
6: jacket, 10: low noise coaxial cable.

Claims (2)

[Claims] 1. An inner conductor, a dielectric layer coated around the inner conductor, a plastically deformable semiconductive layer formed around the dielectric layer, and a semiconductive layer formed around the semiconductive layer. In the low-noise coaxial cable provided with an outer conductor layer to be formed and a jacket covered around the outer conductor layer, the outer conductor layer is embedded in the semiconductive layer and is in close contact with the dielectric layer. A low-noise coaxial cable characterized in that: 2. A step of preparing an inner conductor, a step of coating a dielectric layer around the inner conductor, a step of forming a plastically deformable semiconductive layer around the dielectric layer, Forming an outer conductor layer around the conductive layer, and squeezing the outer conductor layer from outside to embed the outer conductor layer in the semi-conductive layer to form the outer conductor layer and the semi-conductive layer into a dielectric material. A method for producing a low-noise coaxial cable, comprising the steps of: adhering to a layer; and coating a jacket around the outer conductor layer.