JP2010027209A - Coaxial cable, method of manufacturing the same, and multicore cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial cable with a reduced diameter, which is reduced in hardness and thickness of the cable, has less fluctuations in withstanding voltage properties, has a coating easily stripped in terminal treatment, and is easily assembled even when a plurality of the coaxial cable are assembled to form a multicore cable, and to provide a method of manufacturing the coaxial cable. <P>SOLUTION: In the coaxial cable, a central conductor 2 is coated with an insulating layer 3, an outer conductor 4 is wound around an outer periphery of the insulating layer 3 to form a shield layer, and a resin tape 5 is spirally wound around an outer periphery of the outer conductor to form an outer sheath. The resin tape 5 has a resin layer 6 and a thermosetting adhesive layer 8, wherein the thermosetting adhesive layer 8 is provided in oblique stripes to the longitudinal direction of the resin tape 5. After the resin tape 5 has been wound by a lap winding, the thermosetting adhesive layer 8 is heated and cured to be bonded and fixed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thin coaxial cable, a method for manufacturing the same, and a multi-core cable in which a plurality of coaxial cables are assembled.

  In recent years, miniaturization and high performance have been demanded in all electronic devices such as medical probes such as ultrasonic diagnostic apparatuses and communication devices such as mobile phones, and correspondingly, coaxials used as cable harnesses or inside devices. The cable is also required to have a very small diameter. For example, as a coaxial cable, an ultrafine coaxial cable having an outer diameter of 0.25 mm is manufactured, and a multi-core cable formed by twisting a plurality of such coaxial cables is also in practical use.

  FIG. 4 is a diagram illustrating an example of the conventional coaxial cable described above. As shown in FIG. 4A, in the coaxial cable 21, a core is formed by covering a center conductor 22 with an insulating layer 23, and an outer conductor composed of a plurality of ultrafine conductive wires or the like is wound around the outer periphery of the core. And the outer periphery of the shield layer 24 is covered with a jacket 25 (also called a jacket). The shield layer 24 is usually formed by horizontally winding or braiding a plurality of parallel conductive wires, but may be formed by a metal tape.

  For example, as described in Patent Document 1, the jacket 25 is formed by overlappingly winding a plastic tape such as polyester. A typical example of the polyester tape is a polyethylene terephthalate (PET) tape. When a resin tape such as a polyester tape is lap-wrapped, an adhesive layer is provided so that the wound tape is not unwound and the overlapping portions of the tape are bonded.

However, if the adhesive layer is overlapped, the resin tape adheres to the shield layer 24, so that it is difficult to expose the shield layer 24 during terminal processing. On the other hand, when the lap winding is performed with the adhesive layer on the outer side, when the coaxial cable is wound, the cables are caught and cannot be fed out. Therefore, normally, the resin tape 25a without an adhesive is wound around the outer periphery of the shield layer 24, and the resin tape 25b with an adhesive is wound on the outer periphery of the shield layer 24 so that the adhesive is inside.
JP 2006-32073 A

  However, the conventional micro coaxial cable has two resin tapes wrapped and heat-bonded, so the inner resin tape is tightly wound and tightly adhered to the shield layer, and the outer conductor of the shield layer is connected during terminal processing. Difficulties with the exposure work remain.

  Moreover, since the conventional coaxial cable has two resin tapes wound on top of each other, it tends to be thick and hard. Further, as shown in FIG. 4B, when two resin tapes 25a and 25b are overlapped and wound, a part a where two tapes partially overlap (a part indicated by an alternate long and short dash line), and three or four sheets A portion b (a portion indicated by a dashed ellipse) is generated. As described above, since the conventional coaxial cable 21 has a variation in the overlap of the resin tape 25, the withstand voltage characteristic provided to the resin tape such as a PET tape also varies.

  The present invention has been made in view of the above circumstances, reduces the hardness and thickness of the cable, has no variation in withstand voltage characteristics, has a coating that can be easily peeled off during terminal processing, and collects a plurality of cables. An object of the present invention is to provide a small-diameter coaxial cable that can be easily assembled even when a multi-core cable is used, and a manufacturing method thereof.

  A coaxial cable according to the present invention is a coaxial cable in which a central conductor is covered with an insulating layer, an outer conductor is wound around the outer periphery of the insulating layer to form a shield layer, and a resin tape is spirally wound around the outer periphery to form a jacket. The tape has a resin layer and a thermosetting adhesive layer, and the thermosetting adhesive layer is provided in an oblique stripe shape with respect to the length direction of the resin tape.

  In the coaxial cable manufacturing method according to the present invention, the center conductor is covered with an insulating layer, the outer conductor is wound around the outer side of the insulating layer to form a shield layer, and a resin tape is spirally wound around the outer conductor to coat the outer sheath. The resin tape has a resin layer and a thermosetting adhesive layer, and the thermosetting adhesive layer is provided in an oblique stripe shape with respect to the length direction of the resin tape. Then, after the resin tape is wound in an overlapping manner, the thermosetting adhesive layer is heat-cured and bonded and fixed.

  According to the coaxial cable of the present invention, the hardness and thickness are reduced, there is no variation in withstand voltage characteristics, and the outer cover is easily peeled off during terminal processing. In addition, since a thermosetting adhesive is used for bonding to the outer resin tape that forms the jacket of the coaxial cable, when forming a multi-core cable, at the heating temperature at the time of extrusion molding of the cable jacket, The adhesive is not melted and does not protrude from the outer surface. For this reason, the coaxial cables are not bonded to each other, and can be assembled while maintaining good electrical and mechanical characteristics.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining the outline of a coaxial cable according to the present invention, FIG. 2 is a diagram for explaining a winding form of a resin tape, and FIG. 3 is a diagram for explaining a multi-core cable of the present invention. In the figure, 1 is a coaxial cable, 2 is a central conductor, 3 is an insulating layer, 4 is an outer conductor (shield layer), 5 is a resin tape (outer coating), 6 is a PET tape (resin layer), 7 is a pigment layer, Reference numeral 8 denotes an adhesive layer, 10 denotes a multi-core cable, 11 denotes a coaxial cable, 12 denotes an insulating cable, 13 denotes a resin tape (press winding), and 14 denotes a jacket.

  As illustrated in FIG. 1A, a thin coaxial cable 1 according to the present invention has an outer periphery of a center conductor 2 covered with an insulating layer 3, and an outer conductor 4 is wound around the outer periphery of the insulating layer 3 as a shield layer. Further, a resin tape 5 is wound around the outer periphery as a jacket (also called a jacket).

  In such a coaxial cable 1 having a small diameter, first, the center conductor 2 is covered with an insulating layer 3 such as a fluororesin or a foamed fluororesin to form an insulated cable serving as a core. This insulated cable is not limited to the single core wire as shown in FIG. 1A as the center conductor 2 but may be a stranded wire obtained by twisting a plurality of thin conductive wires. The insulating layer 3 is usually formed by extruding the fluororesin or winding the fluororesin tape in a spiral shape, and has a predetermined impedance.

  Then, the outer conductor 4 is formed on the insulated cable (core) by winding a plurality of ultrafine conductive wires in parallel in a spiral shape (lateral winding) to form a shield layer. For the conductive wire forming the outer conductor 4, for example, a strand such as a tin-plated alloy wire is used. In addition, as the element wire, a round fine conductive wire that is lightly compressed into a flat fine conductor may be used, and a plurality of wires may be horizontally wound in parallel. The outer conductor 4 may have a braided structure, or may be formed of a copper foil thread or a metal tape.

  The resin tape 5 has an adhesive applied on one side. However, if the adhesive is applied on the entire surface of the tape, the adhesive is pushed out from the gap between the tapes and easily adheres to the external conductor when the tape is wound. Become. Therefore, the resin tape 5 used in the present invention is a tape such as a polyester tape or a polyolefin tape with an adhesive to which an adhesive is applied in a form in which the amount of the adhesive is reduced. Specifically, as shown in FIGS. 1B and 1C, the resin tape 5 with an adhesive is, for example, a pigment on one side of the PET tape 6 as a resin layer that is a base material of the resin tape 5. A layer 7 is formed, and an adhesive layer 8 is provided on the layer 7 in an oblique stripe shape (zebra shape). Here, the pigment layer 7 may not be provided and may remain transparent. The adhesive layer 8 may contain a dye.

  As described above, the resin tape 5 includes the resin layer such as the PET tape 6 and the adhesive layer 8 provided on the resin layer, and the adhesive layer 8 is linear with an oblique width Da. , Formed with an interval Db. That is, the adhesive layer 8 is applied to the tape surface in a relatively uniform and simple pattern in a stripe shape with a reduced amount of adhesive. The width Da of the adhesive layer 8 is made narrower (for example, about 1/3) than the interval Db of the adhesive non-application area. For example, when the tape width W is about 2.0 mm and the width Da of the adhesive layer 8 is 0.5 mm, the interval Db where the adhesive is not applied is about 1.5 mm.

  In the present invention, a thermosetting adhesive obtained by mixing a curing agent such as polyisocyanate with a phenol resin, an epoxy resin, a polyester resin, or the like that is cured by heating is used as the adhesive layer 8. The adhesive layer 8 is applied to the PET tape 6 in an uncured state in advance, and after the resin tape 5 is wound around the outer conductor 4, the adhesive layer 8 is bonded and cured by heating to fix the bonded portion.

  As an example of using the PET tape 6 as the resin layer (base material) of the resin tape 5, other tape materials such as polyethylene naphthalate (PEN) and polypropylene (PP) can be used. As the PET tape 6, one having a width W of 0.9 mm to 4 mm may be adopted. Further, the thickness T of the PET tape 6 is about 1.5 to 6 μm (such as 4.0 μm), the thickness t of the pigment layer 7 is about 1.0 μm, and the thickness d of the adhesive layer 8 is about 1.5 μm. Good.

  FIG. 2 shows a state in which the resin tape 5 is wound around the outer circumference of the outer conductor 4 as a jacket. FIG. 2A shows the state where the adhesive layer 8 of the resin tape 5 is on the outer side and the 1 / This is an example in which two wraps are spirally stacked. FIG. 2B is a schematic diagram showing an overlapping state of the winding of the resin tape 5.

  As shown in FIG. 2, the resin tape 5 is wound spirally with the outer periphery of the outer conductor 4 being overlapped. In this case, the resin tape 5 is wound so that the diagonal striped adhesive layer 8 is on the outside and the surface of the base material PET tape 6 to which the adhesive is not applied is on the inside. The adhesive layer 8 is hidden by being in contact with the inner surface of the PET tape 6 at the overlapping surface of the 1/2 wrap, but the remaining portion is exposed to the outer surface of the winding.

  However, since the adhesive layer 8 of the resin tape 5 is a thermosetting adhesive, it does not become an adhesive state even if it is in contact with the PET tape 6 on the overlapping surface simply by being wound in an unheated state. Further, the adhesive layer 8 exposed on the outer surface of the winding is not sticky, and the adhesive layer 8 is not sticky at the time of feeding from the feeding reel. However, after the resin tape 5 is wound, the thermosetting adhesive layer 8 is bonded and cured by heat treatment, and is bonded and fixed so that the wound state of the resin tape 5 is not loosened.

  As the heat treatment, a method of passing a cable through a high-temperature heating furnace in an online state after winding the resin tape 5 can be used. In this case, the adhesive layer 8 exposed on the outer surface of the wound resin tape 5 is also cured at the same time, has no adhesiveness after curing, and can be wound as it is with a take-up reel.

  The resin tape 5 that forms the outer sheath of the coaxial cable formed as described above is in contact with the surface of the outer conductor 4 that forms the shield layer only on the opposite surface to which the adhesive layer 8 is not applied. Adhesion by the adhesive 8 does not occur. As a result, it is possible to use a single resin tape instead of two conventional resin tapes (see FIG. 4), which is thinner than conventional coaxial cables and increases flexibility. It becomes possible. In addition, the adhesive layer 8 is exposed on the surface of the outer surface of the resin tape 5 after being wound and bonded, but is already in a cured state. Absent.

  Further, as schematically shown in a partial cross section in FIG. 2 (B), the coaxial cable 1 according to the present invention can be used as a jacket by winding a single resin tape, so that the overlapping width is adjusted. By doing so, the overlap of the tapes can be easily made uniform (for example, two sheets in a 1/2 overlap). As a result, variations in withstand voltage characteristics can be reduced, and unevenness on the outer surface of the cable can be reduced, resulting in a clean appearance. Furthermore, since only one resin tape 5 needs to be wound, the tightening can be reduced and stripping is facilitated.

  Although the coaxial cable according to the present invention has been described above, the present invention is a multi-core cable (also referred to as a coaxial multi-core cable) in which the coaxial cable is stored in a plurality of slot rods or a plurality of coaxial cables are covered with a tube. ).

  FIG. 3 is a cross-sectional view showing an example of a multi-core cable in which a plurality of the coaxial cables described above are assembled. A multi-core cable 10 illustrated in FIG. 3 is a structure in which a plurality of the coaxial cables 11 described above are aggregated to be multi-core. In addition to the coaxial cable, the multi-core cable 10 can be gathered together with a normal insulated cable and different types of cables. FIG. 3 shows a multi-core cable in which four coaxial cables 11 and eight insulated cables 12 (or spacers) are gathered and the outside is covered with a jacket 14.

  The jacket 14 of the multi-core cable 10 is formed in various forms according to the purpose of use. For example, the cable assembly is formed by pressing and holding the cable assembly with the resin tape 13 and the like, and the outer periphery thereof is coated with resin by extrusion molding Is done. As a material of the jacket 14, for example, a resin such as polyvinyl chloride, urethane, or silicone is used. In this case, as the press-wound resin tape 13, a resin tape to which the above-described thermosetting adhesive is partially applied can be used.

  When a plurality of coaxial cables 11 according to the present invention are assembled into a multi-core cable 10, the coaxial cable 11 is heated (around 90 ° C.) by the heat of the extrusion molding resin by extrusion molding of the jacket 14. However, since the resin tape wound around the coaxial cable 11 as a jacket is bonded with a thermosetting adhesive, the adhesive does not melt and flow out so as to protrude. Therefore, the assembled cables are not bonded to each other, and the electrical and mechanical characteristics are not deteriorated.

It is a figure explaining an example of the coaxial cable by this invention. It is a figure explaining the winding form of the resin tape of FIG. It is a figure explaining an example of the multi-core cable by this invention. It is a figure explaining a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Coaxial cable, 2 ... Center conductor, 3 ... Insulating layer, 4 ... Outer conductor (shield layer), 5 ... Resin tape (outer coating), 6 ... PET tape (resin layer), 7 ... Pigment layer, 8 ... Adhesion Agent layer, 9 ... Adhesive uncoated region, 10 ... Multi-core cable, 11 ... Coaxial cable, 12 ... Insulated cable, 13 ... Resin tape (press roll), 14 ... Jacket.

Claims (3)

A coaxial cable that covers a central conductor with an insulating layer, wraps an outer conductor around the outer periphery of the insulating layer to form a shield layer, and spirally wraps a resin tape around the outer periphery.
The resin tape has a resin layer and a thermosetting adhesive layer, and the thermosetting adhesive layer is provided in an oblique stripe shape with respect to the length direction of the resin tape. Coaxial cable.   A multi-core cable, wherein a plurality of coaxial cables according to claim 1 are assembled to form a multi-core cable. A method of manufacturing a coaxial cable in which a central conductor is covered with an insulating layer, an outer conductor is wound around the outer side of the insulating layer to form a shield layer, and a resin tape is spirally wound around the outer conductor to form a jacket. ,
The resin tape has a resin layer and a thermosetting adhesive layer, and the thermosetting adhesive layer is provided in an oblique stripe shape with respect to the length direction of the resin tape. A method for manufacturing a coaxial cable, wherein the thermosetting adhesive layer is heat-cured and bonded and fixed after being wound by lap winding.

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