JP2002358842A - External conductor layer structure of very fine coaxial cable, and very fine coaxial cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external conductor layer structure of a very fine coaxial cable with excellent bending property and shielding property, and to provide the very fine coaxial cable. SOLUTION: For the structure of an external conductor layer 13 of the very fine coaxial cable 10, not less than two kinds of strand wires 17, 18, having different conductivity and tensile strength from each other, are evenly arranged at the outer periphery of wires 20 including inside conductors 11 with a diameter not bigger than 0.0799 mm, and a cross section not bigger than 0.005012 mm<2> , along the peripheral direction of the wires 20 respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an outer conductor layer structure of a micro coaxial cable and a micro coaxial cable.
The present invention relates to an outer conductor layer structure of a micro coaxial cable having a conductor diameter of 0.0799 mm or less or a conductor cross-sectional area of 0.005012 mm ² or less, and a micro coaxial cable.

[0002]

2. Description of the Related Art As a micro coaxial cable, as shown in FIG. 3, there is a micro coaxial cable 30 in which an insulating layer 12, an outer conductor layer 33 and a sheath layer 14 are sequentially provided on the outer periphery of an inner conductor 11. In this cable 30, the insulating layer 12
The outer conductor layer 33 is formed by horizontally winding a plurality of element wires 36 around the outer periphery of the outer conductor layer 33.

[0003] In general, the strand 36 of the outer conductor layer 33 takes into account only the conductivity so as to satisfy the shielding characteristics, that is, is composed of a wire having a high conductivity.

In recent years, there has been a demand for a finer coaxial cable to be further reduced in diameter, and accordingly, further downsizing of conductors has been attempted. Conductor diameter or conductor cross-sectional area is small, for example, the conductor diameter of the inner conductor is 0.0799 m
m or a conductor cross-sectional area of 0.005012 mm ² or less (AWG (American Wire Gauge) gauge value of 40 or more), the bending characteristics are sufficiently satisfied only by the strength of the inner conductor. It will be difficult to do.
For this reason, as the strand of the outer conductor layer in this cable, an strand having a constant conductivity and a higher strength than the strand 36 is used in order to improve the bending characteristics.

[0005]

However, since the strength of a conductor generally decreases when high conductivity is to be obtained, and the conductivity is low when high strength is to be obtained. It is difficult to achieve both high conductivity and high strength contradictory characteristics.

Therefore, the conductor diameter of the inner conductor is 0.0799.
In a micro coaxial cable with a conductor cross section of 0.005012 mm ² or less, the bending characteristics of the micro coaxial cable are maintained by using a high-strength wire as a wire of the outer conductor layer. The properties were not satisfactory.

An object of the present invention, which has been made in view of the above circumstances, is to provide an outer conductor layer structure of a micro coaxial cable and a micro coaxial cable having good bending characteristics and shielding characteristics.

[0008]

In order to achieve the above object, the outer conductor layer structure of the micro coaxial cable according to the present invention has a conductor diameter of 0.0799 mm or less or a conductor sectional area of 0.005 mm or less.
^Two or more types of element wires having different conductivity and tensile strength are uniformly arranged on the outer periphery of a wire including an inner conductor of 012 mm ² or less over the circumferential direction of the wire.

On the other hand, the micro coaxial cable according to the present invention
Conductor diameter is 0.0799mm or less or conductor cross section is 0.0
A sheath layer is provided on the outer circumference of a conductor obtained by providing the above-described outer conductor layer structure on the outer circumference of a wire including an inner conductor of 05012 mm ² or less.

By making the outer conductor layer structure of the micro coaxial cable as described above, it is possible to obtain a micro coaxial cable capable of achieving a high level of bending characteristics and shielding characteristics.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a micro coaxial cable according to the present invention. The same members as those in FIG. 3 are denoted by the same reference numerals.

As shown in FIG. 1, the structure of the outer conductor layer 13 of the micro coaxial cable according to the present invention is such that a seven-stranded stranded conductor is insulated around the inner conductor 11 having a cross-sectional area of 0.005012 mm ² or less. Insulated wire core (wire material) provided with layer 12
20 having different conductivity and tensile strength on the outer circumference of
More than types of wires (two types of wires 17 and 18 in FIG. 1)
Are arranged uniformly, specifically, alternately in the circumferential direction of the insulated wire core 20.

Of the strands 17, 18, one strand 17 (or 18) is a high-strength strand, and the other strand 18 (or 17) is a highly conductive strand. Specifically, the strand 17
(Or 18) has a tensile strength of 1000 to 1200MP
a, the conductivity is 40 to 60% IACS, preferably the tensile strength is around 1100 MPa, and the conductivity is around 50% IACS, and examples thereof include a Cu-Ag alloy. The strand 18 (or 17) has a tensile strength of 600 to 80.
0 MPa, conductivity 80-95% IACS, preferably tensile strength around 700 MPa, conductivity 90% IACS
Before and after, for example, a Cu-Sn-based alloy or the like can be mentioned.

The structure of the outer conductor layer 13 shown in FIG. 1 is such that the wires 17 and 18 are alternately arranged on the outer periphery of the insulated wire 20 in the circumferential direction of the insulated wire 20.
It is not always necessary to arrange them alternately. For example, in order to further improve the shield characteristics from the shield characteristics of the structure shown in FIG. 1, the number of high-strength strands is limited to the number required to achieve a certain level of bending characteristics. Can be achieved by using high-conductivity strands, but in this case, the number of the strands is different, so that the strands cannot be alternately arranged. Therefore, every few high-strength strands are arranged so that the fewer strands (in this case, high-strength strands) are evenly arranged in the circumferential direction. This eliminates variations in the strength and conductivity of the outer conductor layer 13 in the circumferential direction.

In FIG. 1, two types of wires 1 are shown.
The case of using the wires 7 and 18 has been described. However, it is needless to say that the types of the wires are not limited to the two types, and three or more types of the wires may be appropriately used according to the required bending characteristics and shielding characteristics. May be used. Also in this case, when the number of the individual wires is the same, the individual wires can be alternately arranged on the outer periphery of the insulated wire core 20 in the circumferential direction, but the number of the individual wires varies. In this case, it is preferable to arrange a small number of strands every few wires so that variations in the strength and conductivity of the outer conductor layer 13 in the circumferential direction are eliminated.

Next, the micro coaxial cable 10 according to the present invention will be described.
Means that the cross-sectional area of a seven-stranded stranded conductor is 0.005012
An insulating layer 12 is formed on the outer periphery of the inner conductor 11 having a diameter of ² mm or less to form an insulated wire core 20.
18 are alternately wound around the circumference of the insulated wire core 20 in a horizontal winding around the outer circumference of the insulated wire core 20 to form the outer conductor layer 13. A sheath layer 14 formed by winding a plastic tape around the outer periphery of the provided conductor 21 is provided. Further, a jacket layer (not shown) may be provided on the outer periphery of the sheath layer 14.

The inner conductor 11 may be formed by twisting a plurality of (seven in FIG. 1) wires 20 as shown in FIG. 1, or by a single wire. Good. When the inner conductor 11 is formed of a stranded wire, the cross-sectional area is applied, and when the inner conductor 11 is formed of a single wire, the diameter is applied.

The insulating layer 12 is provided by extrusion coating of a resin or the like. Examples of the resin material forming the insulating layer 12 include PFA (Teflon (registered trademark)) resin, polyethylene, polypropylene, ETFE (ethylene tetrafluoroethylene copolymer) resin, and FEP (ethylene fluoride propylene) resin. .

The outer conductor layer 13 includes a plurality of metal conductor strands 17 and 18 on the outer periphery of the insulated wire core 20 (FIG. 1).
(16 in each) are provided by being wound in a horizontal winding. Here, the horizontal winding means a plurality of wires 1
7 and 18 are simultaneously and spirally wound.

Examples of the material of the plastic tape forming the sheath layer 14 include polyester and polyphenylene sulfide.

The jacket layer is provided by winding a plastic tape or extruding and coating a molten plastic. Examples of the plastic material forming the jacket layer include polyester, polyphenylene sulfide, PFA resin, polyethylene, polypropylene, ETFE resin, and FEP resin.

According to the micro coaxial cable 10 according to the present invention, the outer conductor layer 13 has the above-described structure, so that the conventional micro coaxial cable can be used even if the conductor is downsized due to the reduction in the diameter of the cable. As compared with a cable, the shield characteristics can be improved while maintaining substantially the same bending characteristics.

According to the present invention, the diameter of the inner conductor is 0.0799 mm or less or the cross-sectional area of the conductor is 0.0050 mm or less.
Micro coaxial cable 1 having good bending resistance and shielding characteristics even for micro coaxial cable of 12 mm ² or less
0 is obtained. For this reason, this cable 10 is required to have both high bending characteristics and high shielding characteristics, such as cables for medical equipment and electronic equipment, particularly for ultrasonic diagnostic equipment, endoscope equipment, and liquid crystal display displays. Suitable for cables.

[0025]

Example <Test 1> (Example) 42 AWG (0.003151 m cross-sectional area)
m ² ) An outer layer of an inner conductor made of a Sn-plated copper alloy wire is extrusion-coated with a PFA resin to form an insulating layer.
Obtain a 2 mm insulated core. Next, a wire diameter of 0.025 mm and a tensile strength of 1100MP were formed on the outer periphery of the insulated wire core.
a, a Cu-Ag alloy wire having a conductivity of 50% IACS and a Cu-Sn alloy wire having a wire diameter of 0.025 mm, a tensile strength of 700 MPa, and a conductivity of 90% IACS are alternately arranged in the circumferential direction of the insulated wire core. And an outer conductor layer formed by being wound horizontally around the outer periphery of the insulated wire core and having an outer diameter of 0.25
mm mm of core is obtained. Next, a plastic tape is wound around the outer periphery of the wire core to form a sheath layer, and a micro coaxial cable is manufactured (material of the present invention).

Comparative Example 1 A wire diameter of 0.025 mm, a tensile strength of 900 MPa, and a conductivity of 70% were formed on the outer periphery of an insulated wire core.
A micro coaxial cable is manufactured in the same manner as in Example 1 except that an IACS Cu-Sn alloy wire is wound horizontally to form an external conductor layer (conventional material).

The micro coaxial cables of Example 1 and Comparative Example 1 were subjected to an evaluation test of the shield characteristics. The evaluation of the shielding characteristics was performed on the shielding effect (dB) in the frequency range of 30 MHz to 1 GHz. FIG. 2 shows the evaluation results.

As shown in FIG. 2, the shielding effect of the microfine coaxial cable of Example 1, which is the material of the present invention, is 10% on average in the entire frequency range as compared with the cable of Comparative Example 1.
It was confirmed that it was slightly improved.

As described above, the embodiment of the present invention is not limited to the above-described embodiment, and it goes without saying that various other embodiments can be envisaged.

[0030]

In summary, according to the present invention, the structure of the outer conductor layer of the micro coaxial cable is different from that of the outer conductor of the wire including the inner conductor having a very small diameter or a very small cross section, in that the conductivity and the tensile strength are different. By making more than kinds of strands evenly arranged in the circumferential direction of each wire,
An excellent effect that an ultrafine coaxial cable capable of achieving a bending characteristic and a shielding characteristic at a high level can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a micro coaxial cable according to the present invention.

FIG. 2 is a diagram illustrating shield characteristics of the micro coaxial cables of Example 1 and Comparative Example 1.

FIG. 3 is a cross-sectional view of a conventional micro coaxial cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Micro coaxial cable 11 Inner conductor (conductor) 13 Outer conductor layer 14 Sheath layer 17, 18 Elementary wire 20 Insulated wire core (Wire material) 21 Conductor

Continued on the front page (72) Inventor Yuki Yamamoto 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Hidaka Factory (72) Inventor Akira Matsui 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture No. 1 F-term in Hitachi Cable, Ltd. General Research Laboratory 5G313 AB02 AB05 AC03 AD07 AE08 5G319 FA04 FA08 FC19

Claims (3)

[Claims] 1. The outer conductor layer structure of a micro coaxial cable having an outer conductor layer on the outer periphery of a wire including an inner conductor having a conductor diameter of 0.0799 mm or less or a conductor cross-sectional area of 0.005012 mm ² or less. An outer conductor layer structure of a micro coaxial cable, characterized in that two or more types of strands having different electrical conductivity and tensile strength are uniformly arranged on the outer periphery of the wire in the circumferential direction of the wire. 2. The outer conductor layer structure of a micro coaxial cable according to claim 1, wherein the individual wires are arranged alternately in the circumferential direction of the wire and in a horizontal winding around the outer circumference of the wire. 3. A micro coaxial cable comprising a conductor having the outer conductor layer structure according to claim 1 and a sheath layer provided on an outer periphery of the conductor.