JP2006032073A - Thin coaxial cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-diameter coaxial cable excellent in shielding characteristics and inexpensive.
In a thin coaxial cable 1 having a central conductor 11 and a shield layer 15, a shield layer 15 is formed by lightly compressing a plurality of horizontally wound ultrafine conductors.
[Selection] Figure 1

Description

  The present invention relates to a small-diameter coaxial cable used in a frequency band of 100 MHz or higher.

  A thin coaxial cable used in a frequency band of 100 MHz or more forms a shield layer by braiding or transverse winding of a plurality of ultrafine conductors on the outer periphery of a core formed by extruding and coating an insulator on the outer periphery of a central conductor However, a structure in which a jacket is coated on the outer periphery of the shield layer is common.

  In order to improve the shielding effect, a shield layer may be formed by vertically attaching a Cu-plated polyester tape together with braiding or horizontal winding of an ultrafine conductor (for example, see Patent Document 1).

  Also, a shield layer using an elliptical metal wire (for example, see Patent Document 2), a flattened conductor (for example, see Patent Document 3), or an insulator layer provided with a metal plating layer directly ( For example, many configurations such as Patent Document 4) have been proposed.

  The prior art document information related to the invention of this application includes the following.

JP 2002-352640 A Japanese Patent No. 3296150 JP-A-11-297132 JP 2002-203437 A Japanese Patent Laid-Open No. 11-25758 JP-A-11-111063 JP 2000-57852 A

  In a small-diameter coaxial cable used in a frequency band of 100 MHz or more, particularly in a band of 1 GHz or more, the shielding characteristics are very important, and the configuration described in Patent Document 1 is becoming indispensable. However, Cu-plated polyester tape is very expensive and has a great influence on the cable cost.

  Moreover, the cables of Patent Documents 2 and 3 are difficult to stably manufacture a conductor used for a shield layer over a long length, and are difficult to apply to mass-produced products. This is because it is difficult to form a braided structure with an elliptical metal wire or to wind a flattened conductor.

  In the configuration of Patent Document 4, since the metal plating is directly applied to the insulator layer, it is difficult to peel off the metal plating layer at the time of terminal connection.

  Accordingly, an object of the present invention is to provide a small-diameter coaxial cable that is excellent in shielding characteristics and inexpensive.

  The present invention was devised to achieve the above object, and the invention of claim 1 is a thin coaxial cable having a central conductor and a shield layer, in which a plurality of laterally wound ultrafine conductors are lightly compressed. A thin coaxial cable having the shield layer formed thereon.

  According to the second aspect of the present invention, a plurality of ultrafine conductors are wound horizontally on the outer periphery of a core formed by forming an insulator on the outer periphery of the central conductor, and the plurality of horizontally wound ultrafine conductors are lightly compressed. The thin coaxial cable according to claim 1, wherein the shield layer is formed and a jacket layer is coated on an outer periphery of the shield layer.

  According to a third aspect of the present invention, a plurality of ultrafine conductors are laterally wound on the outer periphery of two parallel cores formed by forming an insulator on the outer periphery of the center conductor, and the plurality of laterally wound ultrafine conductors are provided. The thin coaxial cable according to claim 1, wherein the shield layer is formed by light compression, and a jacket layer is coated on an outer periphery of the shield layer.

  According to the invention of claim 4, a plurality of micro-coaxial cables or a plurality of two-core parallel micro-coaxial cables are twisted, and a plurality of micro-conductors are wound horizontally on the outer periphery of the twisted cables. The thin coaxial cable according to claim 1, wherein the shield layer is formed by lightly compressing the ultrafine conductor, and a jacket layer is coated on an outer periphery of the shield layer.

  According to the present invention, a remarkable effect of excellent shielding characteristics and low cost is exhibited.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a thin coaxial cable showing a preferred first embodiment of the present invention.

  As shown in FIG. 1, the small-diameter coaxial cable 1 according to the first embodiment forms a core 13 by forming an insulator 12 on the outer periphery of a center conductor 11, and a plurality of wires are formed on the outer periphery of the core 13. A shield layer (outer conductor) 15 is formed by a plurality of flat fine conductors 14 formed by horizontally winding a fine conductor and lightly compressing a plurality of horizontally wound fine conductors, and a jacket is formed on the outer periphery of the shield layer 15. Layer 16 is coated.

The central conductor 11 is formed by twisting a plurality of (seven in FIG. 1) strands 10 or a single strand. Examples of the strand 10 include an Ag plated annealed copper wire, an Sn plated annealed copper wire, and an Sn plated copper alloy wire. For example, a conductor having a conductor diameter of 0.127 mm or less or a conductor cross-sectional area of 0.01267 mm ² or less (AWG (American Wire Gauge) gauge value of 36 or more) is used as the center conductor 11. As an indicator of the thickness of the conductor, a conductor sectional area is used when the central conductor 11 is a stranded wire, and a conductor diameter is used when the central conductor 11 is a single wire.

  The insulator 12 is formed by resin extrusion coating or the like. Examples of the resin constituting the insulator 12 include fluororesins such as PFA (Teflon (registered trademark)) resin, ETFE (ethylene tetrafluoride ethylene copolymer) resin, FEP (ethylene propylene fluoride) resin, polyethylene, polypropylene, and the like. Is mentioned.

  As the ultrafine conductor, for example, one having substantially the same size and the same material as the wire 10 is used. Horizontal winding is to wind a plurality of micro coaxial wires simultaneously and spirally.

  Here, the light compression means that each fine conductor having a circular transverse cross section is formed into a flat fine conductor 14 having a substantially transverse cross section by passing it through a compression die or a rolling roller, and adjacent flattening is performed. It means to make the gap formed between the ultrafine conductors 14 as small as possible. The reduction rate of the cross-sectional area of the lightly compressed outer conductor 15 is preferably within 5% of that before lightly compressed.

  The jacket layer (jacket) 16 is formed by extrusion-coating molten plastic, winding a plastic tape, or the like. Examples of the plastic constituting the jacket layer 16 include polyester and polyphenylene sulfide.

  This small-diameter coaxial cable 1 is a cable used in a frequency band of 100 MHz or more, preferably 1 GHz or more, and can be used as a cable for connecting a main body of a notebook computer and a liquid crystal screen through a hinge, for example. .

  The operation of the first embodiment will be described.

  In the thin coaxial cable 1, the shield layer 15 is formed of a plurality of flat fine conductors 14 configured by lightly compressing a plurality of horizontally wound fine conductors. A plurality of fine conductors having a circular cross section are compressed from the inner and outer radial directions and the left and right circumferential directions by light compression, and are formed into a flat fine conductor 14 having a substantially rectangular cross section.

  For this reason, the gap formed between the adjacent flat fine conductors 14 becomes as small as possible, and the contact between the adjacent flat fine conductors 14 is smaller than that of the shield layer formed without lightly compressing the fine conductor having a circular cross section. The area is large.

  Therefore, the thin coaxial cable 1 has a dense structure of the shield layer 15 and the flat and fine conductor 14 is not easily displaced. Therefore, the shielding effect between the inside and outside of the shield layer 15 is high, and the shielding characteristics are excellent. Moreover, since the shield layer 15 is easily formed over a long length by lightly compressing the horizontally wound ultrafine conductor, an expensive Cu-plated polyester tape as in the prior art is unnecessary and inexpensive.

  Further, the thin coaxial cable 1 is excellent in terminal workability because the shield layer 15 can be easily peeled off by removing the jacket layer 16 at the time of terminal connection and unwinding the flat extra fine conductor 14.

  Next, a second embodiment will be described. In the second embodiment, the present invention is applied to a two-core parallel coaxial cable.

  As shown in FIG. 2, the thin coaxial cable 21 includes an insulator 12 formed on the outer periphery of the center conductor 11 to form two parallel cores 13, 13. A shield layer 25 is formed by a plurality of flat fine conductors 14 formed by horizontally winding a fine conductor and lightly compressing a plurality of horizontally wound fine conductors, and the jacket of FIG. A jacket layer 26 similar to the layer 16 is coated.

  Also with this small-diameter coaxial cable 21, for the same reason as described above, the same effect as that of the small-diameter coaxial cable 1 in FIG.

  A third embodiment will be described. In the third embodiment, the present invention is applied to a multi-core cable.

  As shown in FIG. 3, the thin coaxial cable 31 is composed of a plurality of ultrafine coaxial cables 41 twisted and twisted around a plurality of ultrafine coaxial cables 41 (four cores in FIG. 3). A shield layer 35 is formed of a plurality of flat fine conductors 14 formed by horizontally winding a conductor and lightly compressing a plurality of horizontally wound ultrafine conductors, and the jacket layer of FIG. 16 is coated with the same jacket layer 36.

  As the ultrafine coaxial cable 41, a cable using an ultrafine conductor having a circular cross section instead of the flat fine conductor 14 of the thin coaxial cable 1 of FIG. 1, that is, a conventional single core type thin coaxial cable is used. .

  Also with this small-diameter coaxial cable 31, for the same reason as described above, as in the small-diameter coaxial cable of FIG. For this reason, a conventional single-core thin coaxial cable can be used as the ultrafine coaxial cable 41.

  Further, instead of the ultra-fine coaxial cable 41, instead of the flat fine conductor 14 of the small-diameter coaxial cable 21 of FIG. 2, a cross-sectionally round extra-fine conductor is used, that is, a conventional two-core parallel coaxial cable is used. Also good.

  In the above embodiment, the thin coaxial cable has been described as an example of the one-core type in FIG. 1, the two-core type in FIG. 2 (two-core parallel coaxial cable), and the four-core type in FIG. 3 (multi-core cable). The present invention can be applied to any coaxial cable provided with a central conductor and a shield layer.

Example 1
Using a conductor in which seven Ag-plated annealed copper wires with a wire diameter of 0.08 mm are twisted as the central conductor 11, a core 13 is formed by extruding a fluororesin 0.22mm thick as an insulator 12 on the outer periphery. A 0.08 mm Sn plated annealed copper wire is wound horizontally and lightly compressed to form a shield layer 15. Finally, a fluororesin is extruded 0.14 mm thick to cover the jacket 16, and the thin coaxial cable 1 shown in FIG. Produced.

(Example 2)
A conductor in which seven Sn-plated copper alloy wires having a wire diameter of 0.03 mm are stranded is used as the central conductor 11, and a fluororesin is extruded as an insulator 12 on the outer periphery to a thickness of 0.075mm. Further, a Sn-plated annealed copper wire having a wire diameter of 0.05 mm is wound horizontally and lightly compressed to form a shield layer 25. Finally, a polyester tape is wound to form a jacket 26, and the small diameter of FIG. A coaxial cable (two-core parallel coaxial cable) 21 was produced.

(Comparative Example 1)
Using a conductor in which seven Ag-plated annealed copper wires with a wire diameter of 0.08 mm are twisted as the central conductor, a fluororesin is extruded to the outer periphery with a thickness of 0.22 mm, and a double of Sn-plated annealed copper wire with a wire diameter of 0.05 mm A shield layer was formed by braiding, and finally a fluororesin was extruded to a thickness of 0.10 mm to cover the jacket to produce a thin coaxial cable.

(Comparative Example 2)
A conductor in which seven Sn-plated copper alloy wires having a wire diameter of 0.03 mm are twisted is used as the central conductor, and a fluororesin is extruded to a thickness of 0.075 mm on the outer periphery to form two parallel cores. A .03mm Sn-plated copper alloy wire is rolled twice horizontally and then a copper-deposited polyester tape is wound to form a shield layer. Finally, a polyester tape is wound to form a jacket, and a small coaxial cable (two-core parallel coaxial) Cable).

  For each cable of Example 1 and Comparative Example 1, the characteristic impedance (Ω) and the signal attenuation (dB / m) at frequencies 1, 2, 3, 4, 5, and 6 GHz were measured. The results are shown in Table 1.

  As shown in Table 1, the characteristic impedance of Example 1 is 49.2Ω, which is smaller than 50.0Ω of Comparative Example 1, and the attenuation of Example 1 is about 11.5 compared to Comparative Example 1. ~ 17% smaller. Thereby, it has confirmed that Example 1 was excellent in the shield characteristic and the electrical property rather than the comparative example 1 which formed the shield layer by double braiding.

  Similarly, it was confirmed that Example 2 was superior in shield characteristics and electrical characteristics to Comparative Example 2 in which the shield layer was formed by double horizontal winding.

It is a cross-sectional view of the thin coaxial cable which shows the 1st Embodiment of this invention. It is a cross-sectional view which shows 2nd Embodiment. It is a cross-sectional view showing a third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin coaxial cable 10 Strand 11 Central conductor 12 Insulator 13 Core 14 Flat extra fine conductor 15 Shield layer 16 Jacket layer

Claims (4)

  A thin coaxial cable comprising a central conductor and a shield layer, wherein the shield layer is formed by lightly compressing a plurality of horizontally wound ultrafine conductors.   The outer periphery of the core formed by forming an insulator on the outer periphery of the center conductor is laterally wound with a plurality of ultrafine conductors, and the shield layer is formed by lightly compressing the laterally wound multiple ultrafine conductors, The thin coaxial cable according to claim 1, wherein a jacket layer is coated on an outer periphery of the shield layer.   The shield layer is formed by horizontally winding a plurality of ultrafine conductors on the outer periphery of two parallel cores formed by forming an insulator on the outer periphery of the central conductor, and lightly compressing the plurality of horizontally wound ultrafine conductors The thin coaxial cable according to claim 1, wherein a jacket layer is coated on an outer periphery of the shield layer. Twist a multi-core micro coaxial cable or a plurality of 2-core parallel micro coaxial cables, wrap a plurality of ultra-fine conductors on the outer periphery of the twisted cable, and lightly compress the horizontally wound multi-fine conductors The thin coaxial cable according to claim 1, wherein the shield layer is formed and a jacket layer is coated on an outer periphery of the shield layer.

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