JP2018166113A - Coaxial cable and cable prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coaxial cable that avoids damage to and breakage of a central conductor used, even when the central conductor has a small outer diameter, and achieves desired electric characteristics, and a cable prepared therewith.SOLUTION: A coaxial cable has a central conductor, and an insulator formed in a surrounding manner around the central conductor. The insulator has a cavity-containing layer having a plurality of cavities disposed around the central conductor, and a reinforcement layer disposed between the central conductor and the cavity-containing layer to reinforce the cavity-containing layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coaxial cable and a cable using the same.

  Conventionally, in the signal line of a medical cable used for medical applications such as ultrasonic diagnosis, a coaxial structure that can reduce the influence of internal signal leakage and external noise in order to efficiently transmit high-frequency signals. Is employed (see, for example, Patent Document 1).

  In the coaxial structure, in order to reduce the capacitance, a foamed insulator that contains many bubbles and has a lower dielectric constant than a non-foamed insulator that does not contain bubbles is used as the insulator. (For example, refer to Patent Document 2).

JP 2002-367444 A JP 2011-228064 A JP 2012-104371 A Japanese Patent Laid-Open No. 5-54729

  By the way, when forming a foam insulator, bubbles are generated in the insulating resin by a pressure enhancement method such as a physical foaming method or a chemical foaming method (see, for example, Patent Document 3), but the diameter of the medical cable is reduced. When the center conductor having a small outer diameter is used for the purpose, the center conductor cannot withstand the foaming pressure when bubbles are generated and may be damaged or broken.

  In addition, in the pressure enhancement methods such as the physical foaming method and the chemical foaming method, even if an attempt is made to form a thin foam insulation as the diameter of the medical cable is reduced, the bubbles are uniformly dispersed in the insulating resin. It is difficult to form a foamed insulation, and desired electrical characteristics cannot be realized.

  In addition, as a method for forming a foam insulator around the center conductor, a method is also known in which a foam insulation tape is wound around the center conductor to form a foam insulator (see, for example, Patent Document 4). Since the foamed insulating tape contains a large number of bubbles, the foamed insulating tape easily breaks from the bubbles due to the winding tension when it is wound around the center conductor.

  In particular, when a foam insulation tape is wound around a central conductor that is AWG (American Wire Gauge) 48 or less, it is necessary to use a foam insulation tape having a very thin thickness and a very narrow width. Since the foamed insulating tape is broken by the winding tension, it is almost impossible to wrap the foamed insulating tape around the central conductor to obtain a foamed insulator.

  Accordingly, an object of the present invention is to provide a coaxial cable capable of avoiding damage and breakage of the center conductor and realizing desired electrical characteristics even when a center conductor having a small outer diameter is used, and the coaxial cable. It is to provide a cable using the cable.

  The present invention devised to achieve this object includes a center conductor and an insulator formed around the center conductor, and the insulator is disposed around the center conductor. And a reinforcing layer that is disposed between the central conductor and the void-containing layer to reinforce the void-containing layer.

  The void-containing layer preferably includes an opening that expands from the inside of the insulator toward the outside of the insulator.

  The void-containing layer is preferably made of polytetrafluoroethylene or polyethylene, and the reinforcing layer is preferably made of polyethylene terephthalate.

  The void-containing layer is preferably penetrated by the void.

  In the void-containing layer, the voids are preferably arranged in a staggered manner at equal intervals.

  The void-containing layer is preferably thicker than the reinforcing layer.

  Further, the present invention includes a center conductor and an insulator formed around the center conductor, and the insulator has a plurality of gaps arranged around the center conductor. A cable having a core unit formed by twisting a plurality of coaxial cables including a containing layer and a reinforcing layer disposed between the central conductor and the gap containing layer to reinforce the gap containing layer.

  According to the present invention, even when a center conductor having a small outer diameter is used, a coaxial cable capable of avoiding damage and breakage of the center conductor and realizing desired electrical characteristics and the use thereof Could have provided a cable.

It is a cross-sectional schematic diagram which shows the coaxial cable which concerns on this invention. It is a perspective schematic diagram which shows an insulating tape. It is a cross-sectional schematic diagram which shows the medical cable which concerns on this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, a coaxial cable 100 according to a preferred embodiment of the present invention includes a center conductor 101, an insulator 102 formed around the center conductor 101, and an enclosure around the insulator 102. A protective body 103 is formed, a shield 104 is formed around the protective body 103, and a jacket 105 is formed around the shield 104.

  The central conductor 101 constitutes an inner conductor having a coaxial structure, for example, a single wire that is formed of a material having high conductivity such as copper or copper alloy and has a silver plating or tin plating on the surface thereof. Or it consists of a stranded wire.

  The insulator 102 and the protector 103 constitute an insulator having a coaxial structure, and among these, the insulator 102 has a plurality of gaps 106 formed uniformly distributed at equal intervals on one side. And an insulating tape 107 spirally wound around the center conductor 101 with one side as an outer peripheral surface.

  Thereby, the porosity of the insulator 102 can be made uniform over the longitudinal direction of the coaxial cable 100. As a result, the dielectric constant of the insulator 102 becomes uniform over the longitudinal direction of the coaxial cable 100, and the coaxial In the cable 100, desired electrical characteristics can be realized.

  The protector 103 suppresses a reduction in the porosity of the insulator 102 due to foreign matters entering the gap 106 or damage to the insulating tape 107, and the protection wound around the insulator 102. It consists of a protective layer that is non-extruded (tube extruded) around the tape or insulator 102.

  The shield 104 constitutes an outer conductor having a coaxial structure, and includes, for example, a braided shield or a laterally wound shield made of a material having high conductivity such as copper or copper alloy.

  The jacket 105 is formed of, for example, a resin having high mechanical characteristics and chemical resistance such as a fluororesin, and suppresses deterioration of electrical characteristics due to damage to the shield 104.

  The gap 106 is opened toward one surface of the insulating tape 107, and the opening is enlarged toward the surface of the one surface. This is because when the insulating tape 107 is wound around the center conductor 101, the outer peripheral surface arranged outside is longer than the inner peripheral surface arranged inside, so that the insulating tape 107 serving as the outer peripheral surface becomes longer. This is because one side of the film is stretched.

  As shown in FIG. 2, it is preferable that the gaps 106 have a round shape and are arranged in a staggered manner at equal intervals.

  As a result, it is possible to prevent the winding tension when the insulating tape 107 is wound around the center conductor 101 from being locally concentrated, and to effectively prevent the insulating tape 107 from being broken during the production of the coaxial cable 100. It becomes possible to do.

  The insulating tape 107 includes a gap-containing layer 108 having a thickness of about 25 μm or less in which the gap 106 is formed, a reinforcing layer 109 having a thickness of about 5 μm or less, which is thermally fused to the gap-containing layer 108, The total thickness is about 30 μm or less.

  The void-containing layer 108 is made of a material having a low dielectric constant such as polytetrafluoroethylene or polyethylene, and the reinforcing layer 109 is made of a material having a high mechanical strength such as polyethylene terephthalate.

  Among these, the reinforcing layer 109 is particularly preferably formed of super-stretched polyethylene terephthalate having a tensile strength of about 400 MPa.

  Thereby, even if the thickness of the reinforcing layer 109 is about 5 μm or less, it is possible to sufficiently suppress the stretching or breakage of the void-containing layer 108 due to the winding tension when the insulating tape 107 is wound around the central conductor 101. Therefore, it is possible to contribute to reducing the diameter of the coaxial cable 100.

  The insulating tape 107 is embossed or punched by embossing or punching a low dielectric constant sheet made of a material having a low dielectric constant such as polytetrafluoroethylene or polyethylene to form embossed or penetrating holes. The low dielectric constant sheet in which the holes are formed and the reinforcing sheet formed of a material having high mechanical strength such as polyethylene terephthalate are heat-sealed and bonded to form an insulating sheet. Cut to desired width and length.

  As a result, the embossed or through hole becomes a bottomed concave void 106 and the void-containing layer 108 having the void 106 is reinforced by the reinforcing layer 109. Therefore, when the insulating tape 107 is wound around the central conductor 101 It is possible to prevent the void-containing layer 108 from being crushed by the winding tension and to prevent the void 106 from being crushed and to prevent the void-containing layer 108 from being broken starting from the void 106 having a low mechanical strength.

  Note that the void 106 formed through the punching process has a larger volume as the void 106 than the void 106 formed through the embossing process. Therefore, the porosity of the insulator 102 is increased to increase the porosity of the insulator 102. In order to lower the dielectric constant, it is preferable that the void 106 formed through punching is employed and the void-containing layer 108 is penetrated by the void 106.

  The gap 106 may be a groove type. However, it is more preferable that the void 106 has a round shape because the low dielectric sheet with embossed and through holes formed therein is integral and does not separate, and thus the low dielectric sheet and the reinforcing sheet can be easily attached. .

  Therefore, according to the coaxial cable 100 according to the present embodiment, even if the central conductor 101 having a small outer diameter is used in order to reduce the diameter of the coaxial cable 100, the foamed insulator is used as the insulator 102. Therefore, the central conductor 101 can be prevented from being damaged or broken.

  Moreover, according to the coaxial cable 100 according to the present embodiment, the thin insulating tape 107 is used for the purpose of forming the thin insulator 102 as the coaxial cable 100 is made thinner. Even in this case, since the voids 106 are uniformly present in the void-containing layer 108, desired electrical characteristics can be realized.

  Furthermore, in the coaxial cable 100 according to the present embodiment, the thin insulating tape 107 is used for the purpose of forming the thin insulator 102 as the coaxial cable 100 is reduced in diameter. Even if it exists, since the space | gap content layer 108 is reinforced with the reinforcement layer 109, it is hard to fracture | rupture with the winding tension at the time of winding the insulating tape 107 around the center conductor 101. FIG.

  Therefore, according to the coaxial cable 100 according to the present embodiment, even when the insulating tape 107 is wound around the central conductor 101 that is AWG (American Wire Gauge) 48 or less, the insulating tape 107 does not break. The insulating tape 107 can be wound around the central conductor 101 to form the insulator 102.

  As shown in FIG. 3, a plurality of core unit 200 formed by twisting a plurality of coaxial cables 100 are bundled with, for example, a binding tape 301, a braided shield 302, a sheath 303, etc. It can also be used as a cable 300. As a result, the diameter of the medical cable 300 can be reduced.

  As described above, according to the present invention, even when the center conductor 101 having a small outer diameter is used, damage and breakage of the center conductor 101 can be avoided and desired electrical characteristics can be realized. The coaxial cable 100 and a cable using the same can be provided.

DESCRIPTION OF SYMBOLS 100 Coaxial cable 101 Center conductor 102 Insulator 103 Protective body 104 Shielding body 105 Jacket 106 Gap 107 Insulation tape 108 Gap content layer 109 Reinforcement layer 200 Core unit 300 Medical cable

Claims (7)

A central conductor;
An insulator formed around the central conductor;
With
The insulator includes a void-containing layer having a plurality of voids disposed around the central conductor, and a reinforcing layer disposed between the central conductor and the void-containing layer to reinforce the void-containing layer. A coaxial cable characterized by   2. The coaxial cable according to claim 1, wherein the void-containing layer includes an opening in which the void expands from the inside of the insulator toward the outside of the insulator.   The coaxial cable according to claim 1, wherein the void-containing layer is made of polytetrafluoroethylene or polyethylene, and the reinforcing layer is made of polyethylene terephthalate.   The coaxial cable according to claim 1, wherein the void-containing layer is penetrated by the void.   The coaxial cable according to any one of claims 1 to 4, wherein each of the voids is arranged in a staggered manner at equal intervals in the void-containing layer.   The coaxial cable according to claim 1, wherein the void-containing layer is thicker than the reinforcing layer.   A central conductor, and an insulator formed around the central conductor, wherein the insulator has a plurality of voids disposed around the central conductor, and the center. A cable comprising: a core unit formed by twisting a plurality of coaxial cables formed of a reinforcing layer disposed between a conductor and the void-containing layer to reinforce the void-containing layer.

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