JP2001283649A - Plural-core cable and cable bundle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plural-core cable having improved terminal machining and handling performances for sufficient high-speed transmission. SOLUTION: The cable 1 (the plural-core cable) comprises cores 10, 20 having center conductors 11, 21 and insulators 12, 22 covering the respective peripheries of the center conductors 11, 21, a drain wire 4, and a shield conductor 5 covering the peripheries of the cores 10, 20 and the drain wire 4 in package. The cores 10, 20 are mutually differentiated in cable-sectional geometry on the shield conductor 5 by a cavity Sa caused by the existance of the drain wire 4 and have substantially the same effective dielectric constant or effective electrostatic capacity in the state of being covered with the shield conductor 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-core cable and a cable bundle, and more particularly to a multi-core cable having a center conductor and an insulator covering the periphery of the center conductor, and the multi-core cable. The present invention relates to a multi-core cable including a shield conductor that collectively covers the periphery of a wire, and a cable bundle including a plurality of the multi-core cables.

[0002]

2. Description of the Related Art Wiring for connection between automatic measuring instruments such as IC testers and backplane wiring boards of exchanges needs to transmit high-speed differential transmission signals between connected devices. In particular, with the recent increase in the speed of operation of electronic devices, for example, the time width of a 1-bit signal is on the order of 10 ^-9 seconds, that is, high-speed transmission exceeding 1 Gbps is also performed.

[0003] As a cable used for such high-speed transmission wiring, a multi-core cable having a plurality of, for example, two core wires is generally widely used. More specifically, a core conductor coated with an insulating layer is arranged in parallel with the center conductor, a shield conductor is wound around the core wire and a drain wire (drain wire), and the periphery of the shield conductor is further covered with a jacket ( An example is a two-core parallel cable covered with a sheath. The drain wire is a conductor wire for contacting the shield conductor and grounding the shield conductor.

[0004] The form of a two-core parallel cable having such a drain wire, particularly the arrangement of the drain wire, is, for example, the following first to third forms: [First form] A single drain wire disposed between adjacent core wires or both core wires in the same manner, [Second embodiment] one of the side-by-side core wires closer to the outside (closer to the shield conductor) ) In which one drain wire is arranged, [Third embodiment] one in which two drain wires are arranged on both outer sides of the juxtaposed core wires, and a total of two drain wires are used. I have.

[0005]

Here, the present inventors have studied the workability and workability when connecting to the terminal with respect to the two-core parallel cable having the above-described first to third embodiments. Obtained knowledge. First, when the terminal of the cable of the first embodiment is connected by a connector, it is necessary to open a space between two core wires connected to the connector terminal, take out the drain wire, and connect the drain wire to the ground terminal. Therefore, the work of taking out both the core wire and the drain wire becomes complicated.

In the cable of the third embodiment, the width of a cross section perpendicular to the longitudinal direction of the cable (hereinafter, referred to as "cable cross section") tends to be larger than that of the first embodiment and to be bulky. . In addition, two drain wires must be processed,
This leads to an increase in the number of work steps. In addition, the drain wires on both sides of the core wire become obstacles, and the workability when connecting the core wire to the terminals is reduced.

[0007] The cables of the first or third form are:
The cable has a structure in which the core wire and the drain wire are arranged axially symmetrically in the cross section of the cable, and as described above, the connection workability to the terminal tends to be insufficient. On the other hand, the cable of the second embodiment makes it easy to take out the drain wire, and
Both the core wire and the drain wire can be easily connected to the terminals. Further, the cross-sectional width of the cable can be reduced as compared with the third embodiment. Therefore, the cable having the second embodiment has better workability and handleability than the cables having the first and third embodiments.

In a high-speed transmission cable, if there is a difference in signal transmission speed for each core, the time required for a signal to reach a destination device will differ.
As a result, a transmission error of a signal may be caused, and at the same time, a failure such as loss of the signal itself may occur.

[0009] Taking the case of high-speed transmission at a data rate of about 1 Gbps using a two-core parallel cable as an example,
The difference in signal propagation time between the two cores is one of the signal width.
It is desirably ^1/0 (that is, 10 ⁻¹⁰ seconds) or less. Generally, the difference in propagation time per used cable length is called "skew". When transmitting at 1 Gbps using a two-core parallel cable having a length of 10 m, the skew should be 10 ^-10, that is, 100
It is desired that the pressure be suppressed to psec or less.

As a result of repeated studies on high-speed transmission of the two-core cable having the second form, the present inventors have found that the conventional two-core cable having such a form has a sufficiently small skew. Cannot be necessarily obtained, and it has been found that a reading error of a transmission signal tends to easily occur in high-speed transmission exceeding 1 Gbps.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a multi-core cable which is excellent in workability and handleability of a terminal and which can sufficiently perform high-speed transmission. .

[0012]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have further studied and found that the cable having the above-mentioned second form and a similar form has a different transmission speed for each core. Factors that are more likely to occur. In other words, in a multi-core cable in which a member other than the core wire such as the drain wire is unevenly distributed in the cable cross section in the vicinity of any core wire, a gap is generated between the core wire close to the member and the shield conductor. I will. As a result, the spacing between the core wire and the shield conductor becomes uneven, and the apparent effective permittivity (equivalent permittivity) of the core wire in a cabled state, and thus the apparent effective capacitance (equivalent capacitance). (Capacitance) changes. As a result, it has been found that the transmission characteristics of the signal are changed, and a transmission speed different from the expected transmission speed is exhibited in a state where the core is not cabled alone, and the present invention has been completed.

That is, the multi-core cable according to the present invention includes a plurality of core wires having a center conductor and an insulator covering the periphery of the center conductor, and a plurality of core wires around the plurality of core wires. And a covering shield conductor, wherein at least one of the plurality of core wires is provided so that a geometric arrangement state with respect to the shield conductor in a cable cross section is different from other core wires. The plurality of cores have substantially the same effective permittivity or effective capacitance when covered with the shield conductor.

In the multi-core cable configured as described above, the core wires having different geometric arrangements with respect to the shield conductor in the cable cross section are different from each other in terms of the permittivity in the single state and the effective permittivity in the cabled state. Alternatively, the effective capacitance may be different. In such a case, for example, there is a case where a gap is formed between the shield conductor and the core wire due to the presence of a member other than the core wire, and the gap between the core wire and the shield conductor becomes uneven. When each core is composed of an inner conductor and an insulator of the same kind and diameter, the permittivity of the core and the capacitance uniquely correspond. Therefore, even if the permittivity or capacitance of the core in the single state is matched, the signal transmission speed for each core tends to differ as described above.

On the other hand, in the multi-core cable of the present invention, the effective permittivity or effective capacitance of each core in a state where the core is cabled, that is, in a state where the core is covered with the shield conductor. Are substantially the same,
The signal transmission speed for each core is matched. In addition, it is optional to make another member such as a drain wire to have a thickness excellent in grounding property and handleability, or to arrange it at a position where it can be easily taken out in a cable cross section. At this time, the effective permittivity or effective capacitance of the core wire can be appropriately selected according to the arrangement of such other members.

Each of the core conductors forming each core is formed of the same material, and each of the insulators forming the core having a different geometric arrangement is formed of a different material. Or it is preferable that it has a heterogeneous property.

In this way, the dielectric constant of the insulator can be appropriately changed by changing the material or properties of the insulator. For example, when a resin coating is used as an insulator, the dielectric constant can be easily changed by changing the components (materials) of the resin composition or adjusting the degree of foaming (properties) of a foam. Can be. And, when the center conductor is covered with an insulator having a different material or property, even if the center conductor is made of the same material, further regardless of the same diameter or different diameter,
The dielectric constant and capacitance of each core can be significantly changed.

Further, the multi-core cable according to the present invention comprises:
It is preferable that the present invention is further applied to a device further including a drain wire, wherein the shield conductor collectively covers the periphery of the drain wire and the plurality of core wires. A multi-core cable having a drain wire is useful as a high-speed transmission line as described above, and when the drain wire is covered with a shield conductor together with the core wire,
Air gaps, which cause a difference in signal transmission speed for each core wire, are likely to occur. Therefore, by making the effective permittivity or the effective capacitance of each core wire substantially the same, the deviation of the signal transmission speed can be remarkably reduced.

Further, among the respective core wires, the core wire to which the drain wire is close is defined as a first core wire, and the above-mentioned core wires other than the first core wire are defined as a second core wire. And the second core is the following equation (1) or the following equation (2); ε2 <ε1 (1) (where ε1 and ε2 are the dielectric constants of the first and second cores in a single state, respectively) C2 <C1 (2) (where C1 and C2 indicate the capacitances of the first and second core wires in a single state, respectively). It is suitable.

The gap between the first conductor and the shield conductor in the cross section of the cable tends to be larger than that of the second conductor. As a result, the effective permittivity or effective capacitance in a cabled state tends to be smaller than expected. Therefore, by increasing the dielectric constant or capacitance of the first core in the single state as compared with those of the second core, the effective dielectric constant or effective dielectric constant of the first core is increased. It is possible to make the capacitance close to the value of the second core wire.

Further, the first and second cords are represented by the following formula (3) or (4): ε2 × 1.01 ≦ ε1 ≦ ε2 × 1.10. (3) C2 × 1.01 ≦ C1 ≦ C2 × 1.10 (4) (where ε1, ε2, C1 and C2 are the same as in the expressions (1) and (2)). More preferred. In this way, it is possible to sufficiently secure the adjustment allowance of the effective permittivity or the effective capacitance of the core wire, and when changing the properties of the insulator, the insulation properties and mechanical properties of the insulator are changed. Can be sufficiently prevented.

As a more specific configuration, the plurality of cores are two, the drain is one, and these two cores and one drain are connected to the second core. , A first core wire, and a drain wire in this order. As a result, the ability to take out the drain wire is further improved, and the workability when connecting the multi-core cable to the terminal or the like can be further improved.

Here, the outer diameter (hereinafter simply referred to as “outer diameter”) in a cross section perpendicular to the major axis direction of the core wire and the drain wire.
Are respectively defined as Da and Db, it is more preferable that the relationship represented by the following formula (5); 0.25 ≦ Db / Da ≦ 1 (5) is satisfied, and the following formula (6): 0.25 ≦ Db / Da ≦ 0.67 (6) It is even more preferable that the relationship represented by the following expression is satisfied. In this way, while maintaining excellent handleability of the drain line,
The remarkable increase in the gap between the core wire and the shield conductor caused by the presence of the drain wire is suppressed. In addition, by changing the properties and the like of the insulator to such an extent that the insulating properties and the like are not adversely affected, the difference in the effective permittivity or the effective capacitance between the core wires can be sufficiently reduced.

Further, the cable bundle according to the present invention comprises:
It is characterized by comprising a plurality of multi-core cables of the present invention. With such a cable bundle,
For the above-mentioned reason, signal transmission errors in each of the multi-core cables are unlikely to occur, so that reliability of signal transmission can be improved.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the same components are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a sectional view showing a preferred embodiment of a multi-core cable according to the present invention, and is a view showing an arbitrary cable section. Cable 1 (multi-core cable)
A cord 10 (first cord), a cord 20 arranged in parallel
(Second core wire) and the periphery of the drain wire 4 (drain wire) disposed close to the core wire 10 are collectively covered with the shield conductor 5, and the periphery of the shield conductor 5 is further covered with the outer sheath 6. It is coated.

The core wires 10 and 20 are respectively connected to the center conductor 1.
1 and 21 are covered with insulators 12 and 22. Outer diameter of center conductors 11 and 21 (insulators 12 and 2)
2 and the outer diameters of the insulators 12 and 22 are substantially the same. As the center conductors 11 and 21, for example, a metal having conductivity such as copper, a single wire or a stranded wire made of an alloy or a composite material containing the metal can be used. Further, those having a plating layer on the outer periphery of these single wires or stranded wires may be used. In the present embodiment, the center conductors 11 and 21 are formed of the same conductor wire.

The shield conductor 5 is made of a conductor tape or film member made of metal, a conductor wire, a plastic tape or film on which conductor metal is deposited, and the like around the core wires 10 and 20 and the drain wire 4. It can be formed by a method such as winding and fixing all together. Further, the outer cover 6 is made of a polyolefin resin such as polyethylene,
A vinyl chloride resin such as polyvinyl chloride is extruded around the shield conductor 5, or a tape or film member made of such a resin or another insulating material is wound around the shield conductor 5. It can be formed by such a method.

The materials and properties of the insulators 12 and 22 are not particularly limited, but, for example, it is preferable to use a foamed resin from the viewpoint of achieving high-density and high-speed transmission of transmission signals. Such foamed resin is not particularly limited, and specifically, foamed polyolefin-based resin such as foamed polyethylene, foamed vinyl chloride-based resin such as foamed vinyl chloride, and foamed fluorine-based resin such as foamed polytetrafluoroethylene, etc. No. Insulators 12 and 22 made of these foamed resins can generally contain pores (voids) of 40 vol% or more, and exhibit a low dielectric constant suitable for high-density and high-speed transmission.

The insulator 12 made of such a foamed resin,
For example, the foamed resin may be extruded around the center conductors 11 and 21 to form the center conductor 1.
It can be formed by coating 1, 21.
This may be further cross-linked by irradiation with an electron beam or the like. Further, as another method, a method of winding a tape-shaped or film-shaped member made of such a foamed resin around the center conductors 11 and 21 can also be mentioned.

Examples of other materials which can exhibit a low dielectric constant in the same manner as the foamed resin include a polymer of a liquid resin composition obtained by mixing resin-made hollow spheres which expand with heat in an ultraviolet curable resin. Insulators 12, 2 made of such polymers
As a method of forming 2, the liquid resin composition is applied to the center conductor 1
And a method of applying a UV light while heating to polymerize and crosslink the resin component to obtain a foam.

As the UV-curable resin, known UV-curable monomers, oligomers or prepolymers can be used. For example, urethane (meth) acrylate resin, epoxy (meth) acrylate resin, silicone resin, silicone (meth) A) Monomers, oligomers or prepolymers which are raw materials for acrylate resins, polyester (meth) acrylate resins and the like, and these can be used alone or as a mixture of two or more.

As the resin composition, a thermoplastic resin having excellent compatibility with these ultraviolet curable resins may be mixed. Furthermore, various heat stabilizers, antistatic agents, ultraviolet absorbers, lubricants, antioxidants, coloring agents, foaming agents, processing stabilizers, plasticizers, organic or inorganic fillers which have been conventionally used ( Filler) or the like may be included as an additive.
Further, in order to increase the crosslinking speed and crosslinking density of the resin, it is preferable to blend a polyfunctional monomer such as diallyl adipate, diallyl phthalate, triallyl isocyanurate and the like.

Here, in the present embodiment, the insulator 1
The dielectric constants of the insulators 2 and 22 are different from each other. In particular, the dielectric constant of the insulator 12 is higher than the dielectric constant of the insulator 22. The method for adjusting the dielectric constant of the insulators 12, 22 is not particularly limited,
A method of adjusting the degree of foaming, that is, the porosity (porosity) using the above-described foamed resin or foam is preferable from the viewpoint of simplicity.

Specifically, for example, when the above-mentioned tape-shaped or film-shaped member made of foamed resin is used, members having different degrees of foaming, that is, porosity may be used. When the foamed resin is extruded to form the insulators 12 and 22, a desired porosity can be obtained by appropriately changing the temperature conditions and cooling conditions of the extruder. further,
When a resin composition containing a resin hollow sphere and an ultraviolet curable resin is used, the porosity can be adjusted by appropriately changing the heating temperature to adjust the expansion state (degree of expansion) of the hollow sphere. is there.

In this manner, the dielectric constants of the insulators 12 and 22 are adjusted so that the dielectric constants of the core wires 10 and 20 are more preferably represented by the following formula (1): ε2 <ε1 (1) It is preferable to satisfy the relationship represented by the following formula (3): ε2 × 1.01 ≦ ε1 ≦ ε2 × 1.10. Here, [epsilon] 1 and [epsilon] 2 indicate the permittivity of the core wire 10 and the core wire 20 in an independent state (single body), respectively.

Alternatively, the permittivity of the core wires 10 and 20 may be represented by the following formula (2): C2 <C1 (2), more preferably the following formula (4): C2 × 1.01 ≦ C1 ≦ C2 × 1.10 (4) It is also preferable to satisfy the relationship represented by the following expression. Here, C1 and C2 indicate the capacitances of the core wire 10 and the core wire 20 in a single state (single unit), respectively.

Defining the capacitance in this way is often useful in cable design and design management. Also,
As in the present embodiment, the center conductors 11,
In the case where the porosity of the insulators 12 and 22 is changed by using 21, the dielectric constant of the core wires 10 and 20 corresponds one-to-one with the capacitance, so that the regulation based on the capacitance is particularly effective.

The effective permittivity and the effective capacitance of the cores 10 and 20 in the state of the cable 1 in which the cores 10 and 20 are cabled are the dielectric constants of the cores 10 and 20 in the single state, respectively. ε1, ε2 and capacitance C1, C2
Tends to decrease as compared with In cable 1,
Due to the presence of the drain wire 4, the circumference of the core 10 in contact with the shield conductor 5 is shorter than that of the core 20, and
A gap Sa is formed between the shield conductor 5 and the shield conductor 5. That is, the core wires 10 and 20 are provided so that the geometrical arrangement state with respect to the shield conductor 5 in the cable cross section is different.

As a result, the effective permittivity of the core wire 10 and the degree of reduction of the effective capacitance are larger than those of the core wire 20. Therefore, as shown in Expression (1) or Expression (3),
If the permittivity ε1 or the capacitance C1 of the core 10 in the single state without the cable is made larger than that of the core 20, the effective permittivity in the cabled state of the cores 10 and 20 or The effective capacitance can be substantially equivalent.

Here, if the permittivity ε1 or the capacitance C1 of the core 10 is less than 1.01 times the permittivity ε2 or the capacitance C2 of the core 20, respectively, the volume and position of the gap Sa are However, there is a tendency that the difference between the effective permittivity and the effective capacitance of the cords 10 and 20 cannot be sufficiently compensated.
On the other hand, the permittivity ε1 or the capacitance C1 of the core wire 10 is 1.10 of the permittivity ε2 or the capacitance C2 of the core wire 20, respectively.
If it exceeds twice, there is a possibility that the insulating properties and mechanical properties of the insulators 12 and 22 may be adversely affected.

The larger the outer diameter of the drain wire 4, the more effectively it functions as a ground wire. From this viewpoint, when copper or a copper alloy or the like is used as the conductor material of the drain wire 4, the outer diameter Db (see FIG. 1) is 0.2%.
It is desirably 6 mm or more. On the other hand, when the drain wire 4 is too thick, the rigidity is increased more than necessary,
There is a tendency that handling when connecting the cable 1 to a terminal or the like becomes difficult. Therefore, from this viewpoint, it is desirable that the outer diameter Db of the drain wire 4 be equal to or less than the outer diameter Da of the core wires 10 and 20. In addition, since the handleability may be reduced even if the drain wire 4 is too thin, the outer diameter Db of the drain wire 4 is preferably about 程度 (about 0.25 times) or more of the outer diameter Da of the core wire. It is suitable.

Further, as the outer diameter of the drain wire 4 increases, the gap Sa shown in FIG. 1 increases, and the difference between the effective permittivity or the effective capacitance between the core wires 10 and 20 increases. Tend to be. As described above, when this difference in the effective dielectric constant or the like is compensated for by adjusting the porosity of the insulators 12 and 22, there is a concern that the insulators 12 and 22 may have an adverse effect on the insulating properties and mechanical properties. . In order to avoid this, it is preferable to suppress the difference in the dielectric constant and the like in the single state of the core wires 10 and 20 to about 10% as shown in Expression (3) or Expression (4). In order to realize this, it is desirable that the outer diameter Db of the drain wire 4 is not more than about ／ (about 0.67 times) the outer diameter Da of the core wires 10 and 20.

That is, the outer diameter Da of the core wire and the outer diameter Db of the drain wire 4 preferably satisfy the relationship represented by the following formula (5): 0.25 ≦ Db / Da ≦ 1 (5). It is preferable that the relationship represented by the following formula (6): 0.25 ≦ Db / Da ≦ 0.67 (6) is satisfied.

Further, the present inventors have repeatedly studied the influence of the polar coordinate position of the drain wire 4 on the core wire 10. FIG. 2 is a sectional view showing another embodiment of the multicore cable according to the present invention. The cable 2 (multi-core cable) has the same configuration as the cable 1 shown in FIG. 1 except that the arrangement of the drain wires 4 is different. In the cable 2, the origin is the cross-sectional center of the central conductor 11 of the core wire 10, and an axis connecting this origin and the cross-sectional center of the drain wire 4 forms an angle θ (where θ ≦ 180 °) is approximately 45 °. On the other hand, in the cable 1, the angle θ is set to 90 °.

Then, the outer diameter Db and the angle θ of the drain wire 4 of the cable 2 are independently changed variously,
The 20 effective capacitances were measured and evaluated (the evaluation method will be described later). As a result, when the outer diameter Db of the drain wire 4 is equal to or more than 0.17 times the outer diameter Da of the core wire and the angle θ is equal to or greater than 45 °, the core wires 10 and 20 in the single state before being cabled are formed. It was confirmed that the difference between the capacitances C1 and C2 was significantly different from the difference between the effective capacitances after the cable was formed. At this time, the decrease in the capacitance of the core wire 10 showed a value larger than the core wire 20 by 2 pF / m or more.

According to the cables 1 and 2 configured as described above, the effective permittivity or the effective capacitance of the core wires 10 and 20 in the cabled state is substantially the same as each other. The transmission speed of the signal is
It is surely matched between 0. Therefore, the skew can be made sufficiently small, and problems such as transmission signal reading errors can be sufficiently suppressed. Therefore, high-speed and high-density signal transmission with high reliability is possible. In addition, since the drain wire 4 has a thickness excellent in grounding property and handleability, and can be arranged at a position in the cable cross section that is easy to take out, the cables 1 and 2 excellent in terminal workability and handleability can be obtained. In particular, since the cables 1 are juxtaposed such that the cross-sectional centers of the core wires 10 and 20 and the drain wire 4 are positioned substantially coaxially, the terminal 1 is more excellent in workability and handleability of the terminal. On the other hand, the cable 2 has a smaller maximum width of the cable cross-section than the cable 1, and can be downsized especially when bundled.

Further, the materials or properties of the insulators 12 and 22 are changed, and particularly, the insulators 12 and 22 are made of foamed resin or foam.
Is formed, and the porosity is adjusted, whereby the insulator 1 is formed.
The dielectric constants of 2, 22 can be easily adjusted. Thereby, the dielectric constants ε1, ε2 of the core wires 10, 20 or the capacitances C1, C
2 can be easily adjusted.
There is almost no danger that the productivity will decrease. Moreover, since the foamed resin or foam exhibits a relatively low dielectric constant among the insulating members, signal transmission by the cables 1 and 2 can be performed at higher density and at higher speed. Further, the insulators 12, 2
The above-mentioned resin suitable for the material No. 2 also has an advantage that it is easy to manufacture and obtain and is excellent in economy.

Further, a gap Sa is formed in the vicinity of the core wire 10 to which the drain wire 4 is close, and the permittivity or capacitance when the core wire 10 is cabled compared to the core wire 20. The degree of decrease is large. In contrast, core wires 10, 2
When 0 is provided so as to satisfy the relationship represented by the formula (1) or the formula (2), the effective permittivity or the effective capacitance of the core wires 10 and 20 can be sufficiently matched. it can.

Further, when the cores 10 and 20 satisfy the relationship represented by the equation (3) or (4), the cores 10 and 2
A sufficient adjustment margin of the effective permittivity or the effective capacitance of 0 can be ensured, and the difference between the two can be reliably compensated. Further, it is possible to sufficiently prevent the insulating properties of the insulators 12 and 22 from being adversely affected.

In addition, the core wire outer diameter Da and the drain wire 4
If the core wires 10 and 20 and the drain wire 4 satisfy the formula (5) and the formula (6), the outer diameter Db of the cables 1 and 2 is extremely excellent in handleability of the drain wire 4.
Is obtained. Further, a remarkable increase in the gap Sa between the core wire 10 and the shield conductor 5 is suppressed, and the difference in the effective dielectric constant between the core wires 10 and 20 can be further reduced. Therefore,
The porosity of the insulators 12, 22 can be adjusted to such an extent that the insulating properties and mechanical properties of the insulators 12, 22 are not adversely affected.

FIG. 3A is a schematic sectional view showing the configuration of the first embodiment of the cable bundle according to the present invention.
Is a perspective view thereof. FIG. 4 is a schematic sectional view showing the configuration of the second embodiment of the cable bundle according to the present invention. FIG. 5 is a schematic sectional view showing the configuration of a third embodiment of the cable bundle according to the present invention. 6A to 6D are perspective views schematically showing the configurations of the fourth to seventh embodiments of the cable bundle according to the present invention. FIG. 7 is a plan view showing an eighth embodiment of the cable bundle according to the present invention. Hereinafter, these cable bundles will be described.

In the flat cables 70 and 71 (cable bundles) shown in FIGS. 3A and 3B and FIG. 4, a plurality of cables 1 arranged at a predetermined pitch extend over the entire length of the flat cables 70 and 71 in the major axis direction. Alternatively, they are partially aligned and fixed by fixing members (or common covering) 80, 81. The fixing members 80 and 81 are filled, for example, with a viscous resin composition containing an ultraviolet-curable resin between the cables 1 at predetermined positions and irradiated with ultraviolet rays to be cured. Can be formed.

In order to fill the resin composition between the cables 1, for example, a method in which a thermoplastic resin is added to the resin composition and a film-shaped material is temporarily fixed at a predetermined position by a hot press or the like can be applied. . In this case, it is preferable that the softening temperature of the resin composition, for example, the Vicat softening temperature be lower than the softening temperature of the insulators 12, 22 or the outer cover 6 of the cable 1. This prevents the insulators 12, 22 or the outer cover 6 from being softened once and then solidified again at the time of heating, thereby suppressing the occurrence of local stress relaxation in the cable 1. Therefore, a change in the dielectric constant at the fixing portion can be sufficiently prevented. From the viewpoint of eliminating the same effect due to the heat of polymerization of the resin composition, it is desirable to appropriately adjust the content of the ultraviolet curable resin.

A bundle cable 72 (cable bundle) shown in FIG.
It is integrated with the filler 9 made of yarn or the like, and is integrated over the entire length of the bundle cable 72 in the long axis direction or partially with a fixing member (or a common coating) 82. The flat cables 73 to 76 (cable bundles) shown in FIGS. 6A to 6D have a plurality of flat cables 73 to 7 arranged at a predetermined pitch.
6 are partially aligned and fixed by various fixing members 83 to 86 over the entire length in the major axis direction.

Fixing member 8 in flat cable 73
Reference numeral 3 is used for a so-called hold-down winding, and a plurality of cables 1 are fixed intermittently. Further, the fixing member 84 in the flat cable 74 can be fixed more easily, and fixes the cable 1 discretely. Further, the fixing member 85 of the flat cable 75 is an integrally formed binding member such as a vinyl tie or a resin tie. Further, the fixing member 86 of the flat cable 76 is an adhesive sheet or an adhesive tape having an adhesive on a surface in contact with the cable 1, and can bind the cable 1 by the adhesive force.

The flat cable 77 (cable bundle) is composed of a plurality of cables 1 arranged at a predetermined pitch.
Are aligned and fixed with fixing members (or a common covering) 87 at both ends and an intermediate portion in the long axis direction of the cable 1. The fixing member 87 is formed by, for example, filling the space between the cables 1 at a predetermined position with a viscous resin composition containing an ultraviolet curable resin as described above, and irradiating the cable 1 with ultraviolet light to cure the resin. It can be formed using.

According to the flat cables 70 and 71, the bundle cable 72, and the flat cables 73 to 77, a signal transmission error at the time of high-speed transmission is unlikely to occur in each cable 1, so that a large capacity and / or high-speed transmission of heterogeneous signals is performed. Even in the case of transmission, the reliability can be improved. In addition, since the cables are aligned and fixed by the fixing members 80 to 87, a cable bundle having a very small change in dielectric constant or capacitance over the entire length can be obtained. Further, it is possible to effectively prevent complications when routing and wiring a long cable. Furthermore, according to the molding method using the above-described resin composition, local stress relaxation can be prevented when the fixing members 80 to 82 and 87 are formed, so that a change in the dielectric constant or capacitance in the entire length direction can be further reduced. Can be suppressed.

The cables 1 and 2, the flat cables 70 and 71, the bundle cable 72, and the flat cables 73 to 77 can stably exhibit high-density and high-speed signal transmission characteristics. Equipment that requires high transmission, such as wiring that connects between automatic measuring instruments such as IC testers and backplane wiring boards of exchanges, and medical diagnostics that transmit large amounts of data from CT and MRI equipment at high speed. This is very suitable for data transmission lines used in equipment or industrial equipment.

In the above-described embodiment, the cord 1
The method for adjusting the dielectric constants ε1, ε2 of 0, 20 or the capacitances C1, C2 is not limited to the method of changing the porosity of the insulators 12, 22. Instead, the center conductor 11,
21, the outer diameter or material (composition), or the insulator 12,
By changing at least one of the material (material), outer diameter, thickness, and the like of No. 22, the dielectric constants ε1, ε2
Alternatively, the capacitances C1 and C2 can be appropriately adjusted.

The insulators 12 and 22 may be composed of a single layer of foamed resin or a plurality of layers, or may have a structure in which another outer layer (skin layer) is arranged on the outer periphery of the foamed resin layer. Absent. As such an outer layer, for example, vinyl chloride, a copolymer of vinyl chloride and vinyl acetate, or the like can be used. In this case, the rigidity of the cables 1 and 2 and the cable bundle is appropriately increased, and the resistance to breakage and deformation can be improved. Furthermore, the core wire 10 and the core wire 20, the core wires 10, the core wires 20, and the core wire 10 and the drain wire 4 need not necessarily be in contact with each other as long as they are arranged in the vicinity.

Further, it is preferable that the outer shape of the outer cover 6 is formed so that its cross section is polygonal. This makes it easier to stabilize each cable when a plurality of cables 1 and 2 are juxtaposed to produce a cable bundle such as a flat cable. In addition, when a resin composition is used as a material for the fixing member, it is easy to fill the space between the cables. Further, the cable bundle may be, for example, a flat cable in which a plurality of cables 1 and 2 are arranged in a plurality of rows (a plurality of stages). Further, as the fixing member for aligning and fixing or bundling the cables 1 in the bundle cable, a net-like or mesh-like fixing member may be used. in addition,
In the cable bundle, the outer periphery may be covered with a further jacket if necessary.

In the multi-core cable according to the present invention, the shield conductor may be formed integrally with the drain wire. In such a multi-core cable, the phenomenon that the distance between the core wire and the shield conductor becomes uneven due to the presence of the drain wire is unlikely to occur. However, other members, such as an insulated wire covered with a core wire, three or more core wires, and at least one core wire in a cable cross section is geometrically connected to another core wire. In the case of different geometrical arrangements, the interval between the core wire and the shield conductor may be non-uniform. Therefore, a situation may occur in which the effective permittivity or the effective capacitance differs between the core wires, and it is effective to apply the present invention.

[0064]

EXAMPLES Hereinafter, specific examples according to the present invention will be described, but the present invention is not limited thereto.

<Evaluation Method 1: Capacitance of a Single Core Wire> A core wire having a length of 5 m was immersed in a water tank containing water, and the electrode immersed in water and the center conductor constituting the core wire were each subjected to LCR. It is connected to each electrode of a meter (Yokogawa Hewlett Packard; model 4262A). In this state, an AC voltage having a frequency of 1 kHz and an effective voltage of 1 V is applied between the center conductor and the water to measure the capacitance between the center conductor and the water. The measured value of the obtained capacitance is defined as the capacitance of the core wire in the single state.

<Evaluation method 2: Effective capacitance of core wire>
The center conductor and the shield conductor of the core wire constituting the multi-core cable are connected to the respective electrodes of an LCR meter (manufactured by Yokogawa Hewlett-Packard Company; model 4192A), and an AC voltage having a frequency of 1 kHz and an effective voltage of 1 V is connected to the center conductor. The capacitance is applied between the shield conductor and the conductor to measure the capacitance between the two conductors. The measured value of the obtained capacitance is defined as an effective capacitance in a state where the core wire is cabled.

<Evaluation Method 3: Porosity of Insulator> The specific gravity W1 of the insulator piece cut out from the core wire and the specific gravity W2 of the non-foamed pellet of the insulator material before foaming were measured.
According to the relationship shown in the following equation (7), the porosity R of this insulator is
Calculate v. Rv [%] = (W2−W1) / W2 × 100 (7)

<Example 1> A tin-plated annealed copper wire having an outer diameter of 0.48 mmφ was applied to the stranded wire obtained by twisting 7 pieces of annealed copper wire having an outer diameter of 0.16 mmφ at a time of 0.48 mmφ.
1, 21. After extruding and covering foamed polyethylene around the center conductors 11 and 21, the insulator is irradiated with an electron beam to form an insulator 1 made of crosslinked foamed polyethylene.
Thus, a core wire having an outer diameter of 1.1 mm was obtained. At this time, the temperature at the time of extruding the foamed polyethylene was changed, and the core wire 10 arranged on the drain wire 4 side and the other core wire 20 were separately manufactured.

On the other hand, the drain wire 4 is the same conductor wire as the center conductors 11 and 21, that is, the outer diameter is 0.16 m.
A tin-plated annealed copper wire having an outer diameter of 0.48 mmφ was applied to the stranded wire obtained by twisting seven mφ annealed copper wires. On the other hand, an aluminum film having a thickness of 7 μm was adhered to one surface of a polyester tape having a thickness of 6 μm to obtain an aluminum adhesive tape as a shield conductor 5.

After the shield conductor 5 is wound around the core wires 10 and 20 and the drain wire 4 so as to circumscribe the core wires 10 and 20, polyvinyl chloride is extruded around the periphery thereof to form a 0.25 mm thick wire. The jacket 6 was formed, and a two-core parallel cable was obtained as the cable 1 having the cross-sectional structure shown in FIG.

<Comparative Example 1> A two-core parallel cable was prepared in the same manner as in Example 1 except that the core wire 20 was used instead of the core wire 10, that is, two core wires 20 were used as the core wires. A cable was made.

<Measurement and Evaluation> The evaluation methods 1 to 5 described above were applied to the two-core parallel cable manufactured in Example 1 and Comparative Example 1.
By using No. 3, the capacitance of the core wire alone, the effective capacitance of the core wire, and the porosity of the insulator were evaluated. Table 1 shows the measurement results.

[0073]

[Table 1]

As shown in Table 1, in the two-core parallel cable of the first embodiment, the effective capacitance of each of the two core wires is smaller than the capacitance in the single state, and is equal to each other. The value of was shown. As a result, it was confirmed that the signal transmission speeds of both the cores were substantially equivalent, and there was almost no difference in skew between the cores. On the other hand, in the two-core parallel cable of Comparative Example 1, the effective capacitance of the core was 3.4 pF.
/ M. As a result, a skew of about 80 psec / m occurred in the two core wires, and it was confirmed that the cable was not suitable for high-speed transmission of about 1 Gbps when the cable usage length was 2 m or more.

[0075]

As described above, according to the multi-core cable and the cable bundle according to the present invention, even if the drain wire or the like is arranged at a position where it is easy to handle, the effective dielectric in a state where the core wire is cabled is provided. Since the rates or capacitances are substantially the same, the signal transmission speed for each core is matched. Therefore, it is possible to obtain a multi-core cable and a cable bundle that are capable of extremely high-speed transmission of, for example, 1 Gbps or more, and that are excellent in workability and handling of the terminal.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a multi-core cable according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the multi-core cable according to the present invention.

FIG. 3A is a schematic sectional view showing a configuration of a first embodiment of a cable bundle according to the present invention, and FIG.
It is the perspective view.

FIG. 4 is a schematic sectional view showing a configuration of a second embodiment of the cable bundle according to the present invention.

FIG. 5 is a schematic sectional view showing a configuration of a third embodiment of the cable bundle according to the present invention.

6A to 6D are perspective views schematically showing configurations of fourth to seventh embodiments of the cable bundle according to the present invention.

FIG. 7 is a plan view showing an eighth embodiment of a cable bundle according to the present invention.

[Explanation of symbols]

1, 2, cable (multi-core cable), 4: drain wire (drain wire), 5: shield conductor, 6: sheath, 1
0 ... core (first core), 11,21 ... center conductor, 1
2, 22 ... insulator, 20 ... core wire (second core wire), 70,
71, 73, 74, 75, 76, 77, 78: flat cable (cable bundle), 72: bundle cable (cable bundle), Sa, Sb: void.

Claims (6)

[Claims] 1. A multi-core cable comprising: a plurality of core wires having a center conductor and an insulator covering the periphery of the center conductor; a drain wire; and a shield conductor, wherein the shield conductor is , Collectively covers the periphery of the plurality of core wires and the drain wire, and at least one of the plurality of core wires has a cross section perpendicular to the longitudinal direction of the multi-core cable. A geometric arrangement state with respect to the shield conductor is provided so as to be different from other core wires, and the plurality of core wires have an effective permittivity or an effective electrostatic capacity in a state covered with the shield conductor. A multi-core cable having substantially the same capacity. 2. The core conductors forming the respective cores are formed of the same material, and the insulators forming the cores having different geometric arrangements are formed of different materials. The multi-core cable according to claim 1, wherein the multi-core cable is formed of a material having different properties. 3. A method according to claim 1, wherein, among the core wires, a core wire to which the drain wire is close is defined as a first core wire, and the core wires other than the first core wire are defined as a second core wire. The first and second cores are represented by the following equation (1) or the following equation (2); ε2 <ε1 (1) (wherein ε1 and ε2 are the first and second cores, respectively) The dielectric constant in a single state is shown.) C2 <C1 (2) (where C1 and C2 indicate the capacitances of the first and second core wires in the single state, respectively). The multi-core cable according to claim 1, wherein the following relationship is satisfied. 4. The method according to claim 1, wherein the first and second core wires are of the following formula (3) or the following formula (4): ε2 × 1.01 ≦ ε1 ≦ ε2 × 1.10 (3) And ε2 indicate the permittivity of the first and second core wires in a single state, respectively.) C2 × 1.01 ≦ C1 ≦ C2 × 1.10. (4) (where C1 and C2 are 4. The multi-core cable according to claim 3, wherein a relationship represented by the following formulas is satisfied. 5. The method according to claim 5, wherein the plurality of cores are two, the drain line is one, and the two cores and the one drain line are the second core.
The core wire, the first core wire, and the drain wire are arranged side by side in this order.
Multi-core cable described in. 6. A cable bundle comprising a plurality of multi-core cables according to claim 1.