JP2009211855A - Coaxial flat cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial flat cable in which a plurality of coaxial cables each with a shield conductor spirally wound around in a different direction are arranged so that there are no unevennesses in inter-line pitches at terminal parts, and at the same time, each coaxial cable is free from disconnection or meandering as a common outer coating is extrusion-molded. <P>SOLUTION: A plurality of coaxial cables 1a, 1b with center conductors 2a, 2b formed of twisted wires, and with shield conductors 4a, 4b spirally wound around them are arrayed in a row and are coated with a common outer coating 7 formed by extrusion-molding. Each coaxial cable 1a, 1b includes a twisting direction of the center conductors 2a, 2b contrary to a spiral winding direction of the shield conductors 4a, 4b, and a plurality of the coaxial cables 1a, 1b with the spiral winding directions of the shield conductors different from each other are arrayed in a given alignment order. As the given alignment order, for example, adjacent coaxial cables are so arranged that spiral winding directions of the shield conductors are different from each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coaxial flat cable in which a plurality of coaxial cables are arranged in a row and are integrally covered with a common jacket by extrusion molding.

  A flat cable is known in which several tens of micro coaxial cables are arranged in a row and covered with an extruded resin or laminated with tape from the upper and lower surfaces. A coaxial cable used for a flat cable, for example, uses a stranded wire as a central conductor, an insulator made of a fluororesin coaxially on the outer periphery, and a shield conductor (also referred to as an outer conductor) on its outer side. It is formed by winding and having a shape in which the outer periphery is covered with a jacket. Although the shield conductor may be formed of a braid, the cable diameter is large, so that it is not preferable as an ultrafine coaxial cable, and a horizontal winding is usually used.

  As for the plurality of coaxial cables arranged in a row as a flat cable, the winding direction of the shield conductor is usually the same shape that is horizontally wound in the same direction. However, in the flat cable configured as described above, when the shield is exposed by removing the common jacket at the end in order to form the terminal portion, the winding direction of the shield conductor is inclined obliquely in one direction. For this reason, it is difficult to remove the common jacket straight, and a slight variation occurs in the line pitch. If the line pitch varies, there is a problem in that it takes time to connect the central conductor of each coaxial cable to a connector or a group of terminals on a circuit board arranged at a predetermined pitch. Another problem is that internal stress due to winding of the shield conductor occurs due to change over time, the flat cable is twisted, the terminal portion is lifted, and it is difficult to work on the terminal.

As a method for solving the above problems, for example, Patent Document 1 discloses a flat cable in which the winding direction of the horizontal winding of the shield conductor is an alternating arrangement of right-handed and left-handed windings in adjacent coaxial cables. Yes. Patent Document 2 discloses a flat cable in which the same number (including alternating arrangement) of first (S-twisted) and second (Z-twisted) coaxial cables having different shield conductor directions are arranged.
JP 2001-229742 A JP 2002-133951 A

  As disclosed in Patent Literature 1 and Patent Literature 2 above, when the winding direction of the horizontal winding of the shield conductors of adjacent coaxial cables is alternately changed to remove the common jacket in the terminal portion formation, Generation of variations in the pitch between lines can be suppressed. However, in the techniques disclosed in Patent Document 1 and Patent Document 2, a plurality of coaxial cables are integrated by bonding a pair of laminate tapes as a common jacket. Each coaxial cable will not be squeezed.

  However, when a plurality of coaxial cables with a plurality of shield conductors applied in a horizontal winding are arranged in a row and integrated with a common jacket by extrusion molding, each coaxial cable is subjected to ironing due to the pressure of the extruded resin. Become. In this case, the thin shield conductor of the coaxial cable is formed of a copper alloy wire to ensure the tensile strength and is relatively hard. Therefore, when the shield conductor is squeezed, the force to return the winding is restored. Work.

  For this reason, when the common jacket is formed by extrusion molding, each coaxial cable tends to rotate in a direction in which the winding of the shield conductor is released. The force that the coaxial cable attempts to rotate is accumulated in the direction of the supply reel and may be broken at several tens to several hundreds of meters. For example, even if the disconnection does not occur, the rotation of the coaxial cable enters the common jacket, and the coaxial cable covered with the common jacket may meander in the common jacket. In the meandering within the common jacket, the coating thickness may change, making it difficult to form a terminal.

  The present invention has been made in view of the above-described circumstances, and arranges a plurality of coaxial cables having different winding directions of shield conductors so as to prevent variations in the line-to-line pitch at the terminal portion. An object of the present invention is to provide a coaxial flat cable that does not cause disconnection or meandering in each coaxial cable when the common jacket is extruded.

  The coaxial flat cable according to the present invention is a coaxial flat cable in which a plurality of coaxial cables each having a central conductor formed of a stranded wire and a shield conductor formed by horizontal winding are arranged in a row and covered with a common jacket formed by extrusion molding. . In each coaxial cable, the twist direction of the center conductor and the winding direction of the horizontal winding of the shield conductor are formed in opposite directions, and a plurality of coaxial cables having different winding directions of the horizontal winding of the shield conductor are arranged in a predetermined arrangement order. As a predetermined arrangement order, for example, the adjacent coaxial cables are arranged so that the winding directions of the shield conductors are different from each other.

  According to the present invention, by setting the twist direction of the center conductor to be opposite to the winding direction of the horizontal winding of the shield conductor, each coaxial cable is released in a direction to release the winding of the shield conductor when the common jacket is extruded. Rotation can be suppressed by the central conductor twisted in the opposite direction. As a result, even if the coaxial flat cable is manufactured in a long length, it is possible to prevent the coaxial cable from being broken or meandered.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a coaxial cable used in the present invention, and FIG. 2 is a diagram illustrating a configuration example of a coaxial flat cable according to the present invention. In the figure, 1, 1a and 1b are coaxial cables, 2, 2a and 2b are central conductors, 3 is an insulator, 4, 4a and 4b are shield conductors, 5 is a jacket, 6 is a coaxial flat cable, and 7 is a common outer cable. Indicates the cover.

  As shown in FIG. 1A, a coaxial cable 1 (1a, 1b) used in a coaxial flat cable according to the present invention uses a stranded wire as a central conductor 2 and is coaxially made of a resin material on the outer periphery thereof. The body 3 is disposed, and a shield conductor 4 (also referred to as an outer conductor) is wound around the outer side of the body 3 and formed in a shape in which the outer periphery is covered with a jacket 5.

  The coaxial cable 1 uses, for example, a stranded wire (corresponding to AWG42, a twist pitch of 0.7 mm to 1.2 mm) of seven silver-plated copper alloy wires having an outer diameter of about 0.025 mm as the central conductor 2. And an insulator 3 whose outer surface is coated with an insulating material made of fluororesin to a thickness of 0.045 mm to 0.055 mm. The shield conductor 4 disposed on the outer peripheral surface of the insulator 3 is, for example, wound with about 20 tin-plated copper alloy wires having an outer diameter of about 0.03 mm in a horizontal winding (winding pitch of 3.5 mm to 5.5 mm). The outer surface is covered with a fluororesin-based resin material having a thickness of about 0.04 mm to form a jacket 5, thereby forming an extremely thin coaxial cable having an outer diameter of about 0.3 mm.

  As the coaxial flat cable of the present invention, two types of the coaxial cable 1a shown in FIG. 1B and the coaxial cable 1b shown in FIG. 1C are used. In the coaxial cable 1a of FIG. 1B, the twist direction of the central conductor 2a of the coaxial cable is the left direction, and the horizontal winding direction of the shield conductor 4a is a right-handed winding. Further, the coaxial cable 1a of FIG. 1C is formed by setting the twist direction of the central conductor 2b of the coaxial cable described above to the left direction and the horizontal winding direction of the shield conductor 4b by right-handed winding.

  That is, in the present invention, a coaxial cable is used in which the twisting direction of the central conductor 2 and the winding direction of the shield conductor 4 are opposite to each other. The coaxial cables 1a and 1b have the same shape, structure, etc., except that the horizontal winding direction of the shield conductor 4 is different between right-handed and left-handed (the twist direction of the central conductor is left-handed and right-handed). The

  As shown in FIG. 2, the coaxial flat cable 6 according to the present invention includes a plurality of coaxial cables 1a and 1b described in FIG. 1 arranged in a line and integrated with a common jacket 7 formed by extrusion using an extrusion molding machine. Shape. FIG. 2A shows an example in which a coaxial cable 1a having a right-handed shield conductor and a coaxial cable 1b having a left-handed shield conductor are alternately arranged. FIG. 2B shows an example in which shield conductors 1a and 1b are alternately arranged every two conductors.

  As a specific example of the coaxial flat cable 6, as shown in FIG. 2 (A), the coaxial cables 1a and 1b are arranged in a line at an arrangement pitch of 0.5 mm alternately with the same number of 15 cores (30 cores in total). Then, cover with a common jacket 7 at once. The common jacket 7 is formed, for example, by extruding polyethylene or flame-retardant polyethylene so that the minimum coating thickness is about 0.05 mm. The coaxial flat cable thereby has a short diameter (cable thickness direction) of 0.41 mm and a long diameter (cable width direction) of 15.0 mm. The coaxial flat cable shown in FIG. 2B can also be formed exactly the same except that the arrangement forms of the coaxial cables 1a and 1b are different.

  When the coaxial outer cable 6 is formed by extrusion molding, the coaxial flat cable 6 is subjected to pressure at the molding point of the extruded resin, so that the shield conductors 4a and 4b are squeezed so that the winding diameter is reduced. The power to work. However, since the shield conductors 4a and 4b are made of a material having a relatively high tensile strength such as a copper alloy (for example, tin copper alloy) as described in the section of the problem of the present invention, the force on the shield conductor is reduced. The restoring force to be released works and the coaxial cables 1a and 1b rotate so as to loosen the winding of the shield conductor. This rotation is accumulated toward the supply direction of the coaxial cables 1a and 1b and may be broken, and there is a risk of meandering in the common jacket 7 even if the breakage is not reached.

  However, in the present invention, the central conductors 2a and 2b of the coaxial cables 1a and 1b are twisted in the opposite direction to the shield conductors 4a and 4b. Therefore, when the coaxial cables 1a and 1b rotate to loosen the winding of the shield conductors 4a and 4b, a force to twist further is applied to the center conductors 2a and 2b. However, since the central conductors 2a and 2b repel against further twisting, this acts to suppress the rotation of the coaxial cable. Thereby, even if the coaxial flat cable 6 is continuously manufactured by a long run by extrusion molding, the coaxial cable can be prevented from being disconnected or meandering in the common coating.

  Further, by arranging the coaxial cables 1a and 1b with the winding directions of the shield conductors opposite to each other alternately for every one or plural pieces, when forming the cable terminal portion, the common jacket is straightened. Can be removed. As a result, it is possible to suppress variations in the line-to-line pitch of the terminal portion, facilitate connection to the connector terminal group and the board circuit, and improve workability. In addition, it is possible to reduce the occurrence of internal stress due to winding of the shield conductor due to changes over time, causing the flat cable to be twisted, and causing the terminal portion to float and difficult to process the terminal.

It is a figure which shows the structural example of the coaxial cable used for this invention. It is a figure which shows the structural example of the coaxial flat cable by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a, 1b ... Coaxial cable, 2, 2a, 2b ... Center conductor, 3 ... Insulator, 4, 4a, 4b ... Shield conductor, 5 ... Outer jacket, 6 ... Coaxial flat cable, 7 ... Common outer jacket.

Claims (3)

A coaxial flat cable in which a central conductor is formed of a stranded wire and a plurality of coaxial cables formed of a lateral winding are arranged in a row and covered with a common jacket by extrusion molding,
A plurality of coaxial cables in which the twist direction of the central conductor and the horizontal winding direction of the outer conductor are formed in opposite directions and the horizontal winding directions of the outer conductor are different from each other are arranged in a predetermined arrangement order. A featured coaxial flat cable.   2. The coaxial flat cable according to claim 1, wherein adjacent coaxial cables are arranged such that the winding directions of the outer conductor are different from each other. A method for producing a coaxial flat cable in which a plurality of coaxial cables each having a central conductor formed of a stranded wire and an outer conductor formed by horizontal winding are arranged in a row and covered with a common jacket by extrusion molding.
A coaxial cable in which the twist direction of the central conductor and the horizontal winding direction of the outer conductor are opposite to each other, and a plurality of coaxial cables in which the horizontal winding direction of the outer conductor is different from each other are arranged in a predetermined arrangement order, A method for producing a coaxial flat cable, characterized in that a common coating is extruded and coated around the periphery.

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