JP2007188738A - Multicore cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multicore cable small in a cable diameter, and capable of ensuring flexibility of the cable, and of preventing fracture of a shield conductor due to flexure. <P>SOLUTION: In this multicore cable, a plurality of signal wires are twined into a signal wire bundle 4; the shield conductor 6 is collectively arranged in the circumference thereof; the signal wire bundle 4 is covered with a pressure winding 5 having a thickness not greater than 60 μm by winding a resin tape around it; and a conductive wire is laterally wound in the outer periphery of the pressure winding 5 in the same direction as the twining direction of the signal wire bundle 4 to form the shield conductor 6. The lateral winding pitch of the shield conductor 6 is set to 0.5-3.0 times of the twining pitch of the signal wire bundle 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multi-core cable used for signal transmission of medical equipment such as wiring in an electronic equipment or an endoscope.

  A multi-core cable used for wiring in an electronic device or signal transmission of a medical device such as an endoscope is required to have a high flexibility in handling and is often subjected to a bending operation. When a motion such as bending is applied with a multi-core cable, the signal lines are rubbed together to generate static electricity. This static electricity affects the signal conductor and ground of the signal line, and also causes noise generation for the signal. For this reason, a conductive tape and a braided conductor are wound around the outer periphery obtained by twisting a plurality of signal lines to form a shield conductor, thereby suppressing the generation of static electricity and noise suppression with respect to an external circuit. (For example, refer to Patent Document 1).

Also, as a multi-core cable that is housed in an endoscope and used to transmit video signals, a plurality of signal wires are twisted in a spiral shape and covered with a shield conducting wire braided on its outer periphery, Alternatively, a technique for spirally winding in a direction opposite to the twisting direction of the signal lines is disclosed. This multi-core cable is housed in a flexible tube of an endoscope together with a light guide, a forceps channel, an operation wire, and the like, and is bent according to the bending of the endoscope flexible tube (see, for example, Patent Document 2).
JP-A-4-319205 JP 2000-156804 A

  A multi-core cable used for an endoscope or the like is required to have a structure with a smaller diameter and flexibility in order to reduce a burden on a patient. The above-mentioned Patent Document 2 discloses a form in which the shield conductor applied to the outer periphery of a plurality of signal lines is wound around a spiral in a direction opposite to the braiding or signal line twisting direction. However, when the shield conductor is formed by braiding, the outer diameter of the cable is increased and the flexibility is reduced as compared with the case where the shield conductor is formed by spiral (horizontal winding). On the other hand, when it is wound around a spiral, as disclosed in Patent Document 2, in order to prevent the shield conductor from falling into the valley between the twisted signal lines, it is wound in a direction opposite to the twisting direction of the signal lines. There is a need.

However, multi-fiber tables are often bent extremely in an endoscope. In this case, when the shield conductor is wound in a direction opposite to the twisting direction of the signal line, the signal line and the shield conductor in the bent portion are rubbed at the intersection. As a result, the shield conductor may break and the internal signal line may break.
The present invention has been made in view of the above-described circumstances, and it is an object to provide a multi-core cable that has a thin cable diameter, ensures the flexibility of the cable, and can prevent breakage of the shield conductor due to bending. To do.

  A multi-core cable according to the present invention is a multi-core cable in which a plurality of signal lines are twisted to form a signal line bundle, and a shield conductor is collectively disposed on the outer periphery thereof. The shield wire is covered with the following restraining windings, and a conductor is horizontally wound around the outer periphery of the restraining windings in the same direction as the twisting direction of the signal wire bundle. The horizontal winding pitch of the shield conductor is preferably 0.5 to 3.0 times the twist pitch of the signal wire bundle.

  According to the present invention, since the horizontal winding direction of the shield conductor is the same as the twist direction of the signal wire bundle, when the cable is bent, the shield conductor and the signal line do not intersect at the bent portion, and resistance to bending is reduced. Since it does not occur, flexibility can be increased. Furthermore, since the contact area between the shield conductor and the outer surface of the signal line bundle is increased, the rubbing portions are dispersed, and the fracture life can be extended.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a multi-core cable according to the present invention, and FIG. 2 is a view for explaining a configuration example of a signal line bundle of the multi-core cable. In the figure, 1 is a multi-core cable, 2 is a coaxial wire, 3 is an insulated wire, 4 is a signal wire bundle, 5 is a restrained winding, 6 is a shield conductor, 7 is a cable jacket, 10 is an inner conductor, 11 is an insulator, Reference numeral 12 denotes an outer conductor, and 13 denotes an insulating coating.

  As shown in FIG. 1, a multi-core cable 1 according to the present invention is composed of a signal wire bundle 4 in which a plurality of coaxial wires 2 or insulated wires 3 are assembled in a form in which only one kind or both are combined. . A plurality of coaxial wires 2 or insulated wires 3 (hereinafter referred to as signal wires including both) are integrated into a signal bundle 4 by twisting together about 3 to 20 signal wires constituting one unit. . A resin tape is wound around the outer periphery of the signal wire bundle 4 to form a restraining winding 5 to maintain the aggregated state of a plurality of signal lines and smooth the unevenness generated on the outer peripheral surface of the signal wire bundle 4.

  A plurality of conductive wires are wound horizontally (wound in a spiral shape) on the outer surface of the holding winding 5 to form a shield conductor 6, and a cable jacket 7 is applied to the outer surface of the shield conductor 6 to form a multi-core cable. When used as an endoscope cable, a composite cable with a small number of cores of signal lines is used, so that it is difficult to arrange the signal lines and to form a circular shape. For this reason, since the appearance tends to deteriorate, the inner assembly arrangement is made as close to the natural circle as possible.

  As shown in FIG. 2, a plurality of coaxial wires 2 or insulated wires 3 can be used as the signal wire bundle 4 as described above, and the coaxial wire 2 is used when the frequency used is a high frequency signal. In the case of a low frequency signal, an insulated wire can be used. FIG. 2 shows an example in which nine coaxial wires 2 are arranged outside the five insulated wires 3. In addition to this, a power line (low frequency), a pair line, and the like may be combined.

  As the configuration of the coaxial line 2, for example, a configuration in which the inner conductor 10, the insulator 11, the outer conductor 12, and the insulating coating 13 are sequentially arranged coaxially is used. In the coaxial wire 2, a twisted wire such as a copper or tin-plated copper alloy wire made of a good electrical conductor is used for the inner conductor 10, for example, seven tin-plated copper alloy wires having an outer diameter of about 0.025 mm. It is formed by twisting. In addition to a stranded wire, a single wire can also be used.

  The insulator 11 is formed of an insulating material such as Teflon (registered trademark) resin by tape winding or extrusion molding so that the thickness becomes about 0.06 mm. For example, the outer conductor 12 is made of a tin-plated copper alloy wire having an outer diameter of about 0.03 mm by horizontal winding or braiding, and is used for shielding, and a plastic tape such as polyester having a thickness of about 0.04 mm is provided on the outer surface thereof. The insulation coating 13 is formed by winding or molding with a molding machine, and the outer diameter is formed to be a coaxial line of about 0.3 mm.

  The insulated wire 3 is a signal wire that does not have the outer conductor of the coaxial wire 2, and is the same in shape as an insulated wire in which the outer periphery of the conductive wire is insulated with an insulating material. For example, like the coaxial wire 2, the inner conductor 10 is formed by twisting seven tin-plated copper alloy wires having an outer diameter of about 0.025 mm, and the outer periphery thereof is an insulator 11 such as Teflon (registered trademark) resin. For example, an insulating wire having an outer diameter of about 0.2 mm is formed.

  Usually, as disclosed in Patent Document 2, when winding a conductor wire for forming a shield conductor on the outer surface of a signal wire bundle in which a plurality of signal wires are twisted and bundled, it is opposite to the twisting direction of the signal wire bundle. However, in the present invention, the conductor wire is horizontally wound in the same direction as the twisting direction of the signal wire bundle 4 to form the shield conductor 6. However, if the conductor wire is horizontally wound in the same direction as the twisting direction of the signal wire bundle 4, the conductor wire horizontally wound in the valley generated between the signal wires may drop, and the shield conductor may not be wound correctly. For this reason, in the present invention, a resin tape is wound between the signal wire bundle 4 and the shield conductor 6 to apply the restraining winding 5 so that the conducting wire does not fall into the valley between the signal wires.

  The restraining winding 5 is formed with a thickness of 60 μm or less by winding polyester or a fluororesin-based resin tape or the like. If the thickness of the restraining roll 5 exceeds 60 μm, it may not be possible to bend flexibly with respect to the sudden bending of the endoscope flexible tube. Therefore, it is desirable that the restraining winding 5 is as thin as possible (for example, 2 μm or more) and thin enough to withstand the winding of the shield conducting wire.

  The shield conductor 6 is formed by horizontally winding in the same direction as the twisting direction of the signal wire bundle 4 from above the winding 5 while suppressing a plurality of tin-plated copper wires or copper foil yarns. The twist pitch is preferably 0.5 to 3.0 times, more preferably 1.1 to 2.5 times. If the pitch is increased by 1.0, there is a possibility that the shield conductor 6 falls between the signal line bundles 4, and it is desirable to slightly increase or decrease the pitch. If the horizontal winding pitch of the shield conductor 6 is less than 0.5 times, the winding state is stable and easy to bend, but since the number of intersections with the signal lines increases, the bending causes friction at the intersections. there is a possibility. On the other hand, if it exceeds 3.0 times, the winding state becomes unstable, and tension is applied to the shield conductor by bending, which may reduce flexibility.

The outer periphery of the shield conductor 6 is covered with a cable jacket 7. The cable jacket 7 is made of fluorine resin, polyurethane resin, polyvinyl chloride resin, or the like, and is formed by wrapping a resin tape having an appropriate thickness, or by extrusion coating with a molding machine. The cable jacket 7 protects the shield conductor 6 from an external force and fills the surface with irregularities so that the shield conductor 6 is smoothed so as not to be caught in the endoscope.
Table 1 shows the results of investigating the relationship between the ratio of the horizontal winding pitch of the shield conductor to the twisted pitch of the signal wire bundle and the formability, wearability, and flexibility.

  In the multi-core cable configured as described above, since the shield conductor is formed by horizontal winding of a conductive wire, it can be easily bent and have a small diameter as compared with the case where the shielded conductor is formed by braiding the conductive wire. Furthermore, in the present invention, since the shield conductor is formed by horizontal winding in the same direction as the signal wire twisting direction, it is easier to bend compared to the case where the shield conductor is formed by horizontal winding opposite to the signal wire twisting direction. In addition, since the contact surface of the shield conductor with the restraining winding increases and the rubbing portion generated at the time of bending is dispersed, damage to the shield conductor is reduced and the service life can be extended.

It is a perspective view which shows an example of the multi-core cable by this invention. It is a figure explaining the structural example of the signal wire bundle of the multi-core cable by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multi-core cable, 2 ... Coaxial wire, 3 ... Insulated wire, 4 ... Signal wire bundle, 5 ... Reducing winding, 6 ... Shield conductor, 7 ... Cable jacket, 10 ... Internal conductor, 11 ... Insulator, 12 ... External Conductor, 13 ... insulating coating.

Claims (2)

A multi-core cable in which a plurality of signal wires are twisted to form a signal wire bundle, and a shield conductor is collectively arranged on the outer periphery,
The signal wire bundle is covered with a restraining winding having a thickness of 60 μm or less by wrapping a resin tape, and a conductor is horizontally wound around the restraining winding in the same direction as the twisting direction of the signal wire bundle to form a shield conductor. Multi-core cable. The multi-core cable according to claim 1, wherein a horizontal winding pitch of the shield conductor is 0.5 to 3.0 times a twist pitch of the signal wire bundle.

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