JPH03219505A - Coaxial cable - Google Patents

Abstract

PURPOSE:To realize a substantial percentage of hollowness up to 60% or more of an insulating layer, and also increase the mechanical strength of a cable and make the products uniform by arrangedly installing tubular insulators having a prescribed dimension of section between a central conductor and an external conductor. CONSTITUTION:Tubular insulators 2 are arrangedly installed around the external circumference of a central conductor 1 and external conductors 3 are arrangedly installed around the external side of the tubular insulators 2. One of the tubular insulators 2 or a plurality thereof are coiled around the central conductor 1, twisted together with the central conductor 1, or arranged in parallel with the conductor 1. The ratio of the inside diameter of the tubular insulator 2 to the outside diameter thereof is 60% or more. The volumes of the hollow portion 2a of the tubular insulator 2 and the gap portion 6 of the tubular insulator 2 are 60% or more in terms of sectional ratio to the volume of the insulating layer 5. The tubular insulator 2 is great in its mechanical strength and the uniformity of the products of lined up cables is made certain.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coaxial cable used as a signal transmission path of electronic devices such as computers and their peripheral devices.

(Prior Art) With the advanced development of electronic devices such as computers and their peripheral devices, coaxial cables used in this field are also required to have high performance and high reliability. In particular, there is a strong demand for coaxial cables with low transmission energy loss and high signal transmission speed. In order to satisfy this requirement, it is essential to reduce the effective dielectric constant ε by providing voids or pores in the insulating layer provided between the center conductor and the outer conductor.

Therefore, in the past, as shown in FIG. 6, a plastic disk C was disposed around the outer periphery of the center conductor A, and an outer conductor B was supported by the disk C on the outside to obtain a desired internal gap E.
As shown in Figure 7, there are some cases in which an insulating layer made of highly foamed plastic such as polyethylene, polypropylene, PFA, PTFE, etc. is formed between the center conductor A and the outer conductor B. has been done.

Although not shown, there is also a structure in which a Cordel's string is spirally wound around the outside of the center conductor to reduce the effective dielectric constant ε.

(Problem to be Solved by the Invention) However, when the center conductor A and the outer conductor B are separated by a plastic disk C as shown in FIG. Then,
The mechanical strength, such as the tensile strength, bending strength, and bending strength of the gap, becomes extremely weak, making it difficult to handle it in the same way as a normal cable.

Furthermore, when the insulation layer is made of highly foamed plastic as shown in Figure 7, a foaming ratio (porosity) of 60% has not yet been achieved, and if the foaming ratio is increased forcibly beyond this level, foaming combine with each other and the bubble particle size becomes thicker (because
It becomes easy to collapse due to external stress, and the foaming rate becomes unstable, gradually losing uniformity in the longitudinal direction.

In addition, in cases where the cordel cord is wound around the outer circumferential surface of the center conductor, the winding of the cord may sometimes cause distortion in the center conductor.
This led to deterioration of the electrical and physical characteristics of the coaxial cable.

(Object of the Invention) In view of the above-mentioned problems, the object of the present invention is to provide a coaxial cable that can easily obtain a substantial hollowness ratio of 60% or more in the insulating layer, has strong mechanical strength, and has good product uniformity. It is in.

(Means for Solving the Problems) A coaxial cable according to claim 1 of the present invention has a tubular body 2 made of an insulator disposed around a central conductor l and an insulating layer 5 as shown in FIG. In this coaxial cable, an outer conductor 3 is disposed coaxially with the center conductor 1 on the outer periphery of the coaxial cable, and the tubular body 2 is a porous foam pipe.

A coaxial cable according to a second aspect of the present invention is characterized in that, in the coaxial cable according to the first aspect, a cross-sectional area ratio (hollowness ratio) of the inner diameter to the outer diameter of the tubular body 2 is 60% or more. It is something to do.

A coaxial cable according to a third aspect of the present invention is such that, in the coaxial cable according to the first aspect, the volume of the hollow portion 2a of the tubular body 2 and the gap portion 6 between the tubular body 2 is relative to the volume of the insulating layer 5. It is characterized by a cross-sectional area ratio (substantial hollowness ratio) of 60% or more.

Specifically, the coaxial cable of the present invention has a central conductor l made of single core or stranded wire made of copper, aluminum, etc., with or without plating with tin, nickel, silver, etc. etc.), acrylic resins (PM
One tubular body 2 made of plastic such as MA, etc.), polyolefins (polypropylene, polyethylene, etc.), fluororesins (PFA, etc.), polyamides (6,6-nylon, etc.), polyesters, polycarbonate, polyarylate, etc. Alternatively, the insulating layer 5 is formed by winding or twisting a plurality of them, or by arranging them in parallel with the conductor.

Copper with or without plating with tin, nickel, silver, etc. on the outer periphery of the insulating layer 5 made of the tubular body 2;
Nine outer conductors 3 made of horizontally wound or braided conductive wires such as aluminum or metal foils such as aluminum or copper PET laminated tape are provided coaxially with the center conductor 1, and polyethylene, polyvinyl chloride, etc. The coaxial cable of the present invention is completed by sheathing.

The tubular body 2 is a porous foamed pipe, and is made porous by ordinary foaming melt extrusion, solvent treatment after melt spinning, or stretching treatment. Furthermore, it is desirable that the tubular body 2 has a hollowness ratio of 60% or more, preferably 80% or more, so that the actual hollowness ratio of the insulating layer 5 is 60% or more.

The insulating layer 5 made of the tubular body 2 may be coated with the tubular body 2 as shown in FIG. 2 as needed to improve its mechanical strength.
The tubular bodies 2 may be brought into contact with each other by wrapping a thin tape 11 made of PET, paper, polyethylene, Teflon, etc. on the outside of the tubular bodies 2 . In addition, in order to join the tubular bodies 2 together, as shown in FIG. The insulating layer 5 may be immersed in a solvent, or the gap in the tubular body 2 may be impregnated with the same solvent.

(Function) In the coaxial cable of the present invention, since the insulating layer 5 between the center conductor 1 and the outer conductor 3 is constituted by a tubular body made of a porous foam pipe, the material of the porous foam pipe and By selecting the hollowness ratio of the tubular body 2 or the substantial hollowness ratio of the insulating layer 5, it is possible to set a desired effective dielectric constant ε.

In addition, the total volume of the hollow part 2a of the tubular body 2, the gap 6 between the tubular body 2, and the pores 2b of the porous foam pipe (FIG. 1C),
The ratio (substantial porosity) of the insulating layer 5 to the volume can be easily reduced to 6.
It can be set to 0% or more.

Furthermore, since the void portion is protected by the tubular body 2 itself, the product has strong mechanical strength and is excellent in uniformity in the longitudinal direction of the product.

(Embodiments) FIGS. 1 to 4 show various embodiments of the coaxial cable of the present invention.

Among these embodiments, the coaxial cable shown in FIG. 1 is constructed as follows.

Center conductor 1: Stranded wire made by twisting 7 silver-plated annealed copper wires with an outer diameter of 0.10 mm, standard outer diameter of 0.30 mm.

Tubular body 2: Six polypropylene tubular bodies having an outer diameter of 0.30 mm, an inner diameter of 0.28 mm, and a porosity of 50% are twisted together.

External conductor 3: 30 horizontally wound shields of silver-plated annealed copper wire with an outer diameter of 0.10 mm.

Sheath 4: Flexible vinyl chloride sheath with a wall thickness of 0.5 mm.

The coaxial cable shown in FIG. 2 is constructed as follows.

Center conductor 1: Stranded wire made by twisting 7 silver-plated annealed copper wires with an outer diameter of 0.10 mm, standard outer diameter of 0.30 mm.

Tubular body 2: Six polypropylene tubular bodies having an outer diameter of 0.30 mm, an inner diameter of 0.28 mm, and a porosity of 50% are twisted together.

Thin tape 11: 5μ thickness, 5mm width, PET tape 1/4
Wrap presser.

External conductor 3: 29 horizontally wound shields of silver-plated annealed copper wire with an outer diameter of 0.08 mm.

Sheath 4: Flexible polyvinyl chloride sheath with a wall thickness of 0.5 mm.

The coaxial cable shown in FIG. 3 is constructed as follows.

Center conductor 1: Stranded wire made of 7 silver-plated annealed copper wires with an outer diameter of 0.10 mm, standard outer diameter of 0.30 mm.

Tubular body 2: Six polypropylene tubular bodies having an outer diameter of 0.30 mm, an inner diameter of 0.28 mm, and a porosity of 50% are twisted together.

Adhesive 12 Niacrylic ultraviolet curing resin.

External conductor 3: 29 horizontally wound shields of silver-plated annealed copper wire with an outer diameter of 0.08 mm.

Sheath 4: Flexible polyvinyl chloride sheath with a wall thickness of 0.5 mm.

The coaxial cable shown in FIG. 4 is constructed as follows.

Center conductor 1: Stranded wire made of 7 silver-plated annealed copper wires with an outer diameter of 0.05 mm, standard outer diameter of 0.15 mm.

Tubular body 2: 18 polypropylene tubular bodies having an outer diameter of 0.15 mm, an inner diameter of 0.13 mm, and a porosity of 50% are twisted together.

Outer conductor 3: 5mm width, aluminum 7μ PET 5μ laminate tape.

Sheath 4: Flexible polyvinyl chloride sheath with a wall thickness of 0.5 mm.

Drain wire 7: Silver-plated annealed copper wire with an outer diameter of 0.30 mm.

The coaxial cable of the present invention is manufactured, for example, as shown in FIG.

First, the tubular body 2 is twisted around the outer periphery of the center conductor 1 at an appropriate pitch using a twisting machine 20 shown in FIGS. 5a and 5b. In this twisting machine 20, the tubular body 2 is pulled out from the bobbin 21 in FIG. It is like that.

At this time, in order to improve the mechanical strength of the tubular body 2, a tape winding machine 10 as shown in FIG.
As shown in the figure, a thin tape 11 may be wrapped around the outside of the tubular bodies 2 to bring the tubular bodies 2 into contact with each other. Also, the third
As shown in FIG. The resin is cured by an ultraviolet curable resin curing device 13 comprising a UV lamp 14, a reflecting mirror 15, etc. as shown in d.

The outer conductor 3 is twisted around the outer periphery of the tubular body 2 which has been wrapped with tape or filled with an ultraviolet curing resin in this way, using an outer conductor twisting machine 22 shown in FIGS. 5a and 5e.

It is preferable in terms of mass productivity and production cost to carry out the steps up to this point continuously in a series of equipment as shown in FIG. 5a.

Furthermore, a sheath 4 is formed around the outer periphery of the outer conductor 3 using a normal extruder.
After that, the coaxial cable of the present invention is completed.

The coaxial cable of the present invention includes the material and shape of the tubular body 2;
The present invention is not limited to the presence or absence of presser winding or adhesive, the presence or absence of a sheath, the manufacturing method, etc.

(Effects of the Invention) In the coaxial cable of the present invention, the tubular body 2 is made of a porous foam pipe, and the hollow part 2a of the tubular body 2 and the gap 6 between the tubular bodies 2 constitute the insulating layer 5. There are various effects.

(2) By appropriately selecting the porosity and hollowness ratio of the porous foam pipe, it is possible to set the desired effective dielectric constant ε.

(2) The hollowness ratio of the tubular body 2 is 60% or more, preferably 80%.
With the above, it is possible to easily obtain the insulating layer 5 with a substantial porosity of 60% or more.

■Since the tubular body 2 is used, it has excellent mechanical strength.
As long as the tubular body 2 is not submerged, the insulating layer 5 is reliably secured. Therefore, the outer conductor 3 does not become misaligned or the winding collapses.Moreover, since the tubular body 2 is arranged in the longitudinal direction,
Uniform quality is ensured over the entire length of the product in the longitudinal direction.

[Brief explanation of drawings]

Figure 1a is a sectional view showing an embodiment of the coaxial cable of the present invention, the same figure is an explanatory view showing the structure of the same cable, and Figure 1C is a cross-sectional view showing the structure of the same cable. 2 to 4 are sectional views showing various embodiments of the coaxial cable of the present invention, and Fig. 5 a is an explanatory view showing the manufacturing process of the coaxial cable of the present invention; Figure C is an explanatory diagram of the tape winding machine of Figure A, Figure d is an explanatory diagram of the ultraviolet curing resin curing device of Figure A, Figure e is an explanatory diagram of the ultraviolet curable resin curing device of Figure A. Fig. 6a is a cross-sectional view of a conventional plastic disc type coaxial cable, Fig. 6 is a cross-sectional view taken along line A-A in Fig. a, and Fig. 7 is a conventional foamed plastic insulation material. FIG. 2 is a cross-sectional view of a type coaxial cable. 1 is the center conductor 2 is the tubular body 3 is the outer conductor 5 is the insulating layer 26-

Claims (3)

[Claims] (1) A tubular body 2 made of an insulator is arranged around the center conductor 1 to form an insulating layer 5, and an outer conductor 3 is arranged coaxially with the center conductor 1 on the outer periphery thereof. A coaxial cable characterized in that the tubular body 2 is a porous foam pipe. (2) The cross-sectional area ratio of the inner diameter to the outer diameter of the tubular body 2 is 6.
1. The coaxial cable according to claim 1, wherein the coaxial cable is 0% or more. (3) Hollow portion 2a of the tubular body 2 in the entire insulating layer 5
A coaxial cable according to claim 1, characterized in that a cross-sectional area ratio of the volume of the gap 6 between the tubular body 2 and the volume of the insulating layer 5 is 60% or more.