Composite cable

Abstract

This invention provides a composite cable that allows for miniaturization while suppressing skew. [Solution] The composite cable 1 comprises a bundled core 3 formed by twisting together five or more electric wires 2 including a pair of differential signal lines 21 used for transmitting differential signals, and a fiber interlining 7, a bundled shield layer 4 that covers the bundled core 3 collectively, and a sheath 5 that covers the bundled shield layer 4. The five or more electric wires 2 constituting the bundled core 3 are arranged in a ring shape so that the differential signal lines 21 are adjacent to each other in the circumferential direction, and the electric wires 2 adjacent to each other in the circumferential direction are in contact with each other. The fiber interlining 7 is placed in a central gap 3a surrounded by the five or more electric wires, and in a cross section perpendicular to the longitudinal direction of the cable, the fiber interlining 7 is provided to occupy an area of ​​50% to 90% of the area of ​​the central gap 3a.

Description

Technical Field

[0001] The present invention relates to a composite cable.

Background Art

[0002] In endoscopes, with the trend towards higher functionality and higher image quality, digital transmission image sensors (i.e., image sensors that output the data of captured images as digital signals) are being increasingly applied. And as a cable connected to a digital transmission image sensor, a cable capable of transmitting differential signals is required. As a cable capable of transmitting differential signals, a cable including a twisted pair formed by twisting differential signal lines composed of coaxial lines is generally used.

[0003] Incidentally, as prior art document information related to the invention of this application, there are Patent Documents 1 and 2.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a cable used for a medical device that enters the body, such as an endoscope, in order to reduce the burden on the patient, it is desirable to make the outer diameter as small as possible. However, when a twisted pair formed by twisting a pair of differential signal lines is bundled with other electric wires to form a composite cable, there is a problem that the outer diameter of the composite cable becomes large.

[0006] To address these challenges, one approach is to reduce the diameter of the composite cable by twisting the pair of differential signal lines together with other wires without twisting them in pairs. However, in this case, a physical length difference is more likely to occur between the pair of differential signal lines, leading to increased skew.

[0007] Therefore, the present invention aims to provide a composite cable that can be made thinner while suppressing skew. [Means for solving the problem]

[0008] The present invention aims to solve the above problems and provides a composite cable comprising: a bundled core formed by twisting together five or more wires including a pair of differential signal lines used for transmitting differential signals and a fiber intervening; a bundled shield layer that covers the periphery of the bundled core collectively; and a sheath that covers the periphery of the bundled shield layer, wherein the five or more wires constituting the bundled core are arranged in a ring shape such that the differential signal lines are adjacent to each other in the circumferential direction, and the adjacent wires in the circumferential direction are in contact with each other; the fiber intervening is placed in a central void surrounded by the five or more wires; and in a cross section perpendicular to the longitudinal direction of the cable, the fiber intervening is provided such that it occupies an area of ​​50% to 90% of the area of ​​the central void. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a composite cable that can be made thinner while suppressing skew. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of a composite cable according to one embodiment of the present invention. [Figure 2] This diagram illustrates the problems that can occur when there is too much fiber interposition. [Figure 3] (a) is a photograph showing a cross-section perpendicular to the longitudinal direction of the composite cable of Example 1, (b) is a photograph showing a cross-section perpendicular to the longitudinal direction of the composite cable of Comparative Example 1, and (c) is a photograph showing a cross-section perpendicular to the longitudinal direction of the composite cable of Comparative Example 2. [Modes for carrying out the invention]

[0011] [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] Figure 1 is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of the composite cable 1 according to this embodiment. The composite cable 1 is a thin-diameter cable used, for example, as a cable for an endoscope. The outer diameter of the composite cable 1 is 2 mm or less, more preferably 1 mm or less. The composite cable 1 is also connected to a digital transmission image sensor and used to transmit differential signals output from the image sensor.

[0013] The composite cable 1 comprises a bundled core 3 formed by twisting together five or more electric wires 2, including a pair of differential signal lines 21 used for transmitting differential signals, and fiber interlining 7; a bundled shield layer 4 that covers the bundled core 3 collectively; and a sheath 5 that covers the bundled shield layer 4 collectively. Each part will be described in detail below.

[0014] (Electric wire 2) The composite cable 1 is composed of five wires 2. More specifically, the composite cable 1 is composed of two (a pair) differential signal lines 21, two insulated wires 22, and one coaxial cable 23. The number of wires 2 is not limited to these, and there may be six or more. When four or fewer wires 2 are twisted together, the shape of the bundled core 3 is less likely to be distorted in the first place, so this embodiment focuses on the case where five or more wires 2 are used in the bundled core 3.

[0015] (Differential signal line 21) A pair of differential signal lines 21 are used to transmit differential signals. Each pair of differential signal lines 21 consists of a coaxial cable and comprises an inner conductor 211, an insulator 212 surrounding the inner conductor 211, an outer conductor 213 surrounding the insulator 212, and a jacket layer 214 surrounding the outer conductor 213. The pair of differential signal lines 21 used are identical in configuration.

[0016] The internal conductor 211 of the differential signal line 21 consists of a compressed stranded conductor formed by twisting together multiple (in this case, seven) metal strands 211a and then lightly compressing them to create a roughly circular cross-sectional shape. This configuration allows for a large conductor cross-sectional area while reducing the outer diameter of the conductor, contributing to the reduction in the diameter of the differential signal line 21 and the overall diameter of the composite cable 1. Furthermore, the contact area between adjacent metal strands 211a increases, reducing contact resistance, thereby improving the conductivity of the internal conductor 211 and enhancing its electrical characteristics.

[0017] Silver-plated copper alloy wire was used as the metal strand 211a constituting the internal conductor 211. This configuration allows for improved mechanical strength while suppressing a decrease in conductivity, resulting in an internal conductor 211 that is less prone to breakage even with a small diameter.

[0018] For the insulator 212 of the differential signal line 21, a fluororesin that can be molded into a thin wall is preferable. Here, a PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer) was used as the insulator 212.

[0019] As the outer conductor 213 of the differential signal line 21, a horizontally wound shield was used, in which multiple metal strands 213a were spirally wound around the insulator 212. This configuration improves resistance to bending and other movements, and also prevents the outer conductor 213 from becoming too thick, thus preventing the differential signal line 21 from becoming too large in diameter. As the metal strands 213a constituting the outer conductor 213 were made of silver-plated copper alloy wire, which has high conductivity and mechanical strength, similar to the metal strands 211a constituting the inner conductor 211.

[0020] As the jacket layer 214 of the differential signal line 21, similar to the insulator 212, a fluororesin that can be formed into a thin film may be used. Here, a jacket layer 214 made of PFA was used. The outer diameter of the jacket layer 214, that is, the outer diameter of the differential signal line 21, was set to 0.246 mm.

[0021] (Insulated wire 22) The insulated wire 22 is used for transmitting low-speed signals such as control signals or for power supply. The insulated wire 22 has a conductor 221 and an insulator 222 that covers the periphery of the conductor 221. The conductor 221 is composed of a stranded conductor formed by twisting a plurality of metal strands 221a. As the metal strands 221a constituting the conductor 221, similar to the metal strands 211a and 213a of the differential signal line 21, silver-plated copper alloy wires with high conductivity and high mechanical strength were used. Also, as the insulator 222, similar to the insulator 212 and the jacket layer 214 of the differential signal line 21, a fluororesin that can be formed into a thin film was used. Here, an insulator 222 made of PFA was used. In this embodiment, two insulated wires 22 with different outer diameters are used, but the outer diameters of the two insulated wires 22 may be the same.

[0022] (Coaxial line 23) The coaxial line 23 is used for signal transmission. The coaxial line 23 has an inner conductor 231, an insulator 232 that covers the periphery of the inner conductor 231, an outer conductor 233 that covers the periphery of the insulator 232, and a jacket layer 234 that covers the periphery of the outer conductor 233, respectively. The inner conductor 231 is composed of a stranded conductor formed by twisting a plurality of metal strands 231a. The outer conductor 233 is composed of a horizontally wound shield formed by spirally winding a plurality of metal strands 233a around the insulator 232. As the metal strands 231a and 233a, silver-plated copper alloy wires with high conductivity and high mechanical strength were used. Also, as the insulator 232 and the jacket layer 234, a fluororesin (here, PFA) that can be formed into a thin film was used.

[0023] (Collective core 3, fiber inclusion 7) The cluster core 3 is constructed by arranging five or more (five in this case) electric wires 2 in a ring. Adjacent electric wires 2 in the circumferential direction are in contact with each other. Furthermore, each electric wire 2 is arranged to be in contact with only two electric wires 2 adjacent to it in the circumferential direction. In addition, a pair of differential signal lines 21 are arranged adjacent to each other in the circumferential direction within the cluster core 3. This configuration makes it less likely for physical length differences to occur between the differential signal lines 21 compared to when the differential signal lines 21 are spaced apart, thereby suppressing skew.

[0024] Furthermore, in the composite core 3, the fiber intervening 7 is arranged in a central gap 3a surrounded by five or more (five in this case) electric wires 2. As a result of the inventors' studies, it was found that when five or more electric wires 2 are arranged in a ring, the ring shape cannot be stably maintained unless the amount of fiber intervening 7 placed in the central gap 3a is appropriately controlled. In the composite cable 1 according to this embodiment, in a cross section perpendicular to the longitudinal direction of the cable, the fiber intervening 7 is provided such that it occupies an area of ​​50% to 90% of the area of ​​the central gap 3a. In other words, in the composite cable 1, in a cross section perpendicular to the longitudinal direction of the cable, the ratio of the area of ​​the region without fiber intervening 7 to the total area of ​​the central gap 3a is greater than 10% and less than 50%. By configuring it in this way, it is possible to suppress the collapse of the shape of the composite core 3, which can occur if the amount of fiber intervening 7 is insufficient and some of the electric wires 2 fall into the central gap 3a, or if the amount of fiber intervening 7 is too large and some of the fiber intervening 7 gets stuck between the electric wires 2. By suppressing deformation of the aggregate core 3, physical length differences between the pair of differential signal lines 21 become less likely, and skew can be suppressed. The area occupied by the fiber interlining 7 is defined as the area of ​​the region enclosed by the outer perimeter 8 that surrounds the portion where the fiber interlining 7 is located, in a cross section perpendicular to the longitudinal direction of the cable. Therefore, even if there are gaps in the region enclosed by the outer perimeter 8 (such as small gaps between the fibers constituting the fiber interlining 7), the area of ​​these gaps is included in the area occupied by the fiber interlining 7.

[0025] Furthermore, as shown in Figure 2, if the amount of fiber interlining 7 is too large and some of the fiber interlining 7 gets trapped between the electric wires 2, the fiber interlining 7 will be crushed by the radially inward pushing force (white arrow F) when forming the sheath 5, causing the aggregate core 3 to shrink in diameter. As a result, the arrangement of the metal strands 4a constituting the aggregate core 3 becomes disordered due to the shrinking of the aggregate core 3. If the disorder of the metal strands 4a constituting the aggregate shield layer 4 becomes large, the metal strands 4a are more likely to rub against each other and break when the composite cable 1 is repeatedly subjected to bending or other movements, reducing the composite cable 1's resistance to bending and other movements. As in this embodiment, by providing fiber interlining 7 so that it occupies an area of ​​50% to 90% of the area of ​​the central gap 3a, such problems can be suppressed and the resistance of the composite cable 1 to bending and other movements can be improved.

[0026] It is desirable to use the thinnest possible fibers to make up the fiber interlining 7. More specifically, it is desirable to use fibers with a density of less than 400 denier, more preferably 100 denier or less, to make up the fiber interlining 7. By configuring it in this way, the fiber interlining 7 will hold together well, and the fibers making up the fiber interlining 7 will not easily get caught between the electric wires 2. In this embodiment, polyester (liquid crystal polyester), which is relatively easy to form into a density of about 100 denier and which holds together without gaps, was used as the fiber to make up the fiber interlining 7.

[0027] In the composite core 3, the pair of differential signal lines 21 and the other three wires 2 are arranged facing each other across the cable center. Therefore, in order to balance the tensile strength, the ratio A / B of the sum of the tensile strengths A of the pair of differential signal lines 21 and the sum of the tensile strengths B of the other wires 2 (in this case, two insulated wires 22 and one coaxial wire 23) should be between 0.75 and 1.25. By configuring it in this way, when the composite cable 1 is subjected to bending or other movements, stress concentration on specific wires 2 is suppressed, and the resistance to bending and other movements is improved.

[0028] Furthermore, in this embodiment, the outer diameter of all wires 2 other than the differential signal line 21 included in the aggregate core 3 is smaller than the outer diameter of the differential signal line 21. In addition, in this embodiment, the aggregate core 3 includes wires 2 having an outer diameter of 60% or less of the outer diameter of the differential signal line 21 (the insulated wire 22 with the smaller outer diameter). Generally, when a wire 2 with a smaller outer diameter than others is included, that wire 2 is often placed on the outside or inside of the ring-shaped arrangement of wires 2. However, as a result of the inventors' studies, it was found that in such cases the shape of the aggregate core 3 tends to collapse, and the skew worsens. Even when a wire 2 with a smaller outer diameter is included, by arranging all wires 2, including that wire 2, in a ring and placing an appropriate amount of fiber interposition 7 in the central gap 3a, it is possible to suppress the collapse of the shape of the aggregate core 3 and suppress the skew.

[0029] The twisting direction of the bundled core 3, the twisting direction of the inner conductor 211 of the differential signal line 21, the winding direction of the outer conductor 213, and the twisting direction of the conductor 221 of the insulated wire 22 are all the same. That is, the twisting direction of the bundled core 3 is the same as the twisting direction of the conductors of the wires 2 that constitute the bundled core 3. By configuring it in this way, stress concentration when bending or other movements (especially twisting movements) are applied to the composite cable 1 can be suppressed, and resistance to bending and other movements can be improved.

[0030] Here, the twisting direction of the bundled core 3 is the direction in which the wire 2 rotates from one end to the other, as viewed from one end of the bundled core 3. The twisting direction of the inner conductor 211 is the direction in which the metal strands 211a rotate from one end to the other, as viewed from one end of the differential signal line 21. The winding direction of the outer conductor 213 is the direction in which the metal strands 213a rotate from one end to the other, as viewed from one end of the differential signal line 21. And the twisting direction of the conductor 221 is the direction in which the metal strands 221a rotate from one end to the other, as viewed from one end of the insulated wire 22.

[0031] Furthermore, in this embodiment, no fiber intervening 7 is placed between the annularly arranged wires 2 and the binding tape 6. This configuration suppresses deformation of the aggregate core 3 due to an imbalance in the fiber intervening 7 placed between the annularly arranged wires 2 and the binding tape 6. However, if the amount of fiber intervening 7 increases too much, gas may be generated by the heat during the extrusion molding of the sheath 5, causing defects such as poor appearance. Therefore, in order to reduce the amount of fiber intervening 7, it is not preferable to place fiber intervening 7 between the annularly arranged wires 2 and the binding tape 6.

[0032] (Bind Tape 6) A binding tape 6 is wrapped around the bundled core 3 to hold it in place and prevent the twist from unraveling. The binding tape 6 is wrapped spirally around the bundled core 3 so that a portion of its width overlaps. A resin tape can be used as the binding tape 6. In this embodiment, a binding tape 6 made of polyimide was used.

[0033] (Single Shield Layer 4) The unified shielding layer 4 is a layer designed to improve noise immunity for multiple wires 2 and is connected to the so-called frame ground. The outer conductor 213 of the differential signal line 21 is connected to the so-called signal ground and has a different purpose than the unified shielding layer 4.

[0034] The integrated shield layer 4 consists of a horizontally wound shield formed by spirally winding multiple metal wires 4a. The winding direction of the metal wires 4a in the integrated shield layer 4 (hereinafter referred to as the winding direction of the integrated shield layer 4) is the same as the twisting direction of the aggregated core 3. This configuration suppresses stress concentration when bending or other movements (especially twisting movements) are applied to the composite cable 1, thereby improving resistance to bending and other movements. The winding direction of the integrated shield layer 4 is the direction in which the metal wires 4a rotate from one end to the other end of the composite cable 1, as viewed from one end.

[0035] (Sheath 5) The sheath 5 is a layer that protects the aggregate core 3 and the unified shielding layer 4. It is desirable to use a fluororesin that can be molded into a thin wall for the sheath 5. Here, a sheath 5 made of PFA was used. It is desirable that the thickness of the sheath 5 be slightly thicker than the outer diameter of the metal wires 4a of the unified shielding layer 4. More specifically, the thickness of the sheath 5 should be between 1.0 and 2.0 times the outer diameter of the metal wires 4a of the unified shielding layer 4. This configuration makes it possible to suppress cracking of the sheath 5 when repeated bending and other movements are applied, while suppressing an increase in the diameter of the composite cable 1. In this embodiment, the outer diameter of the metal wires 4a of the unified shielding layer 4 was set to 0.05 mm, and the thickness of the sheath 5 was set to 0.08 mm. In this case, the thickness of the sheath 5 is 1.6 times the outer diameter of the metal wires 4a. The outer diameter of the sheath 5, i.e., the outer diameter of the composite cable 1, is 2.00 mm or less, more preferably 1.00 mm or less, and in this embodiment it was set to 0.84 mm.

[0036] (Manufacturing method for composite cable 1) When manufacturing the composite cable 1, first, the electric wires 2 (in this case, a pair of differential signal wires 21, two insulated electric wires 22, and one coaxial wire 23) and fiber interlining 7 are twisted together to form a composite core 3. At this time, the amount of fiber interlining 7 is set so that, in a cross section perpendicular to the longitudinal direction of the cable, the fiber interlining 7 occupies an area of ​​50% to 90% of the area of ​​the central gap 3a. After that, binding tape 6 is spirally wrapped around the composite core 3. At this time, the binding tape 6 is wrapped so that a portion of the width of the binding tape 6 overlaps.

[0037] Subsequently, multiple metal wires 4a are spirally wound around the binding tape 6 to form a single shield layer 4. Then, a sheath 5 is formed around the single shield layer 4 by extrusion molding. To prevent the resin constituting the sheath 5 from seeping into the single shield layer 4, the sheath 5 is preferably formed by tube extrusion molding. Through the above steps, the composite cable 1 shown in Figure 1 is obtained.

[0038] (Evaluation of skew and cross-sectional shape) Composite cables 1 of Examples 1 and 2 shown in Table 1 were fabricated, and composite cables of Comparative Examples 1 and 2 were also fabricated. Bending tests and skew measurements were performed on these cables. In Examples 1 and 2 and Comparative Example 1, as shown in Figure 1, five electric wires 2 were arranged in a ring, and a fiber interlining 7 was placed in the central void 3a to form a composite core 3. In Examples 1 and 2, 100 denier liquid crystal polyester was used as the fiber interlining 7. In Comparative Example 1, 400 denier aramid fiber was used as the fiber interlining 7. In Examples 1 and 2, the amount of fiber interlining 7 was such that it occupied 80% of the area of ​​the central void 3a. In Comparative Example 2, no fiber interlining 7 was used, and the twist shape of the composite core 3 was different from that of Examples 1 and 2 and Comparative Example 1. In Comparative Example 2, the four wires 2, excluding the insulated wire 22 with a small outer diameter, were arranged in a ring, and the insulated wire 22 with a small outer diameter was placed in the valley between the pair of differential signal lines 21 (the portion between the pair of differential signal lines 21 and the binding tape 6).

[0039] In the bending test, the bending angle was set to 150°, the bending radius to 8.5 times the outer diameter, and the load to 100g. The test was considered successful if the conductor resistance of each wire 2 and the unified shield layer 4 did not increase by more than 5% after 150,000 bending cycles. Skew was measured using TDR (Time Domain Reflectivity Measurement) to determine the propagation delay difference. The target skew value was set to 40 ps / m or less. The results are summarized in Table 1.

[0040] [Table 1]

[0041] Table 1 shows that in Examples 1 and 2, where the fiber interposition 7 occupied between 50% and 90% of the area of ​​the central void 3a, the bending test was passed and the skew was suppressed to 30 ps / m or less. In contrast, in Comparative Example 1, where the amount of fiber interposition 7 was excessive, although the skew was good, the bending test failed because the resistance value of the unified shield layer 4 increased by 8% after 150,000 bending cycles, exceeding the threshold of 5%. In Comparative Example 2, which did not use fiber interposition 7, the bending test was passed, but the skew was 58 ps / m, which was greater than the target value.

[0042] Furthermore, Figure 3(a) shows a cross-sectional photograph of the composite cable 1 of Example 1, Figure 3(b) shows a cross-sectional photograph of the composite cable of Comparative Example 1, and Figure 3(c) shows a cross-sectional photograph of the composite cable of Comparative Example 2. As shown in Figure 3(a), in the composite cable 1 of Example 1, the deformation of the aggregate core 3 is suppressed, and the disorder of the unified shield layer 4 is also minimal. In contrast, in the composite cable of Comparative Example 1, the fiber interposition 7 has become embedded between the electric wires 2 in the aggregate core 3, and the arrangement of the unified shield layer 4 is also greatly disordered (see the area enclosed by the dashed line in the figure).

[0043] (Operation and Effects of the Embodiment) As described above, in the composite cable 1 according to this embodiment, the five or more electric wires 2 constituting the aggregate core 3 are arranged in a ring shape such that the differential signal lines 21 are adjacent to each other in the circumferential direction, and the electric wires 2 adjacent to each other in the circumferential direction are in contact with each other. The fiber interlining 7 is placed in the central gap 3a surrounded by the five or more electric wires 2, and in a cross section perpendicular to the longitudinal direction of the cable, the fiber interlining 7 is provided to occupy an area of ​​50% to 90% of the area of ​​the central gap 3a.

[0044] By configuring the cable in this way, an appropriate amount of fiber interposition 7 can be placed in the central gap 3a, and the deformation of the aggregate core 3 can be suppressed while five or more electric wires 2 are arranged in a ring. This suppresses the increase in skew caused by the physical length difference between pairs of differential signal lines 21. Furthermore, in this embodiment, since the pairs of differential signal lines 21 are not twisted together but are twisted with other electric wires 2, the diameter of the composite cable 1 can be reduced. In other words, according to this embodiment, a composite cable 1 that can be reduced in diameter while suppressing skew can be realized.

[0045] Furthermore, according to this embodiment, deformation of the aggregate core 3 can be suppressed, making it less likely for the aggregate shielding layer 4 to become disordered. As a result, when the composite cable 1 is repeatedly subjected to bending or other movements, breakage of the metal strands 4a constituting the aggregate shielding layer 4 becomes less likely, improving resistance to bending and other movements.

[0046] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals and other symbols in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0047] [1] A composite cable (1) comprising: a bundled core (3) formed by twisting together five or more electric wires (2) including a pair of differential signal lines (21) used for transmitting differential signals and a fiber interlayer (7); a bundled shield layer (4) that covers the bundled core (3) collectively; and a sheath (5) that covers the bundled shield layer (4), wherein the five or more electric wires (2) constituting the bundled core (3) are arranged in a ring shape such that the differential signal lines (21) are adjacent to each other in the circumferential direction, and the circumferentially adjacent electric wires (2) are in contact with each other; the fiber interlayer (7) is placed in a central gap (3a) surrounded by the five or more electric wires; and in a cross section perpendicular to the longitudinal direction of the cable, the fiber interlayer (7) is provided such that it occupies an area of ​​50% to 90% of the area of ​​the central gap (3a).

[0048] [2] The composite cable (1) according to [1], wherein the ratio A / B of the sum of the tensile strengths A of the pair of differential signal lines (21) and the sum of the tensile strengths B of the other wires (2) is 0.75 or more and 1.25 or less.

[0049] [3] The composite cable (1) according to [1], wherein the fibers constituting the fiber interposition (7) are less than 400 denier.

[0050] [4] The composite cable (1) according to [3], wherein the fibers constituting the fiber interposition (7) are 100 denier or less.

[0051] [5] The composite cable (1) according to [4], wherein the fibers constituting the fiber interposition (7) are made of polyester.

[0052] [6] The composite cable (1) according to [1], wherein the outer diameter of all the electric wires (2) other than the differential signal line (21) included in the aggregate core (3) is smaller than the outer diameter of the differential signal line (21).

[0053] [7] The composite cable (1) according to [1], wherein the aggregate core (3) includes the electric wire (2) having an outer diameter of 60% or less of the outer diameter of the differential signal line (21).

[0054] [8] The composite cable (1) described in [1], wherein the differential signal line (21) is a coaxial cable having an internal conductor (211) which is made of a compressed stranded conductor formed by twisting together a plurality of metal strands (211a) and then compressing them.

[0055] (Note) Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. In addition, the present invention can be implemented with appropriate modifications without departing from its spirit. [Explanation of Symbols]

[0056] 1…Composite cable 2...Electric wire 21… Differential signal line 22...Insulated wires 23…Coaxial line 3…Collective Core 3a…Central void 4…Single Shield Layer 5…Sheath 6…Binding tape 7…Fiber interposition

Claims

1. A bundled core is formed by twisting together five or more wires, including a pair of differential signal lines used for transmitting differential signals, and fiber interlining. A single shielding layer that covers the periphery of the aforementioned aggregated core, The system comprises a sheath that covers the periphery of the aforementioned bulk shield layer, The five or more wires constituting the aggregate core are arranged in a ring shape such that the differential signal lines are adjacent to each other in the circumferential direction, and the wires adjacent to each other in the circumferential direction are in contact with each other. The aforementioned fiber interposition is placed in the central void surrounded by the five or more electric wires. In a cross-section perpendicular to the longitudinal direction of the cable, the fiber interposition is provided such that it occupies an area of ​​50% to 90% of the area of ​​the central void. Composite cable.

2. The ratio A / B of the sum of the tensile strengths A of the pair of differential signal lines to the sum of the tensile strengths B of the other wires is 0.75 or more and 1.25 or less. The composite cable according to claim 1.

3. The fibers constituting the aforementioned fiber interposition are those with a denier of less than 400. The composite cable according to claim 1.

4. The fibers constituting the aforementioned fiber interposition are those with a denier of 100 denier or less. The composite cable according to claim 3.

5. The fibers constituting the aforementioned fiber interposition are made of polyester. The composite cable according to claim 4.

6. The outer diameter of all the wires other than the differential signal lines included in the assembly core is smaller than the outer diameter of the differential signal lines. The composite cable according to claim 1.

7. The assembly core includes the wire having an outer diameter of 60% or less of the outer diameter of the differential signal line. The composite cable according to claim 1.

8. The differential signal line consists of a coaxial cable having an internal conductor made of a compressed stranded conductor formed by twisting together multiple metal strands and then compressing them. The composite cable according to claim 1.

Images