# Patent

## Title
Signal transmission cable

## Abstract

A signal transmission cable of the present invention comprises a terminal part electrically connectable to an external device, and a cable including metal wires of eight or more channels that are electrically connectable to the terminal part, the terminal part has a substrate including a plurality of connection parts that are electrically connectable to the external device and connected respectively to the metal wires of the individual channels included in the cable, and the metal wires of the mutually different channels that are adjacently connected at the plurality of connection parts are arranged so as not to be adjacent to each other inside the cable.

## Background
BACKGROUND OF THE INVENTION
Filed of the Invention
The present invention relates to a signal transmission cable.
Background Arts
Japanese Patent No. 4248042 discloses a technology of appropriately arranging contacts (connection parts) on a substrate in order to suppress Near End Crosstalk (NEXT) that occurs between transmission signals and reception signals and Far End Crosstalk (FEXT) that occurs between signals in the same direction. Japanese Patent Application Laid-Open No. 2004-87189 discloses a twinax cable for differential transmission as a signal transmission cable.
Crosstalk tends to occur between metal wires relating to different and adjacent channels of a cable terminal part on a substrate (hereinafter, described as a terminal part) or inside a cable. In the case that the metal wires relating to different channels are adjacent at the terminal part of the substrate of and inside the cable, influence of the crosstalk increases. Here, an arrangement of the metal wires inside the cable is generally determined in consideration of mountability to the substrate. The metal wires that are adjacent to each other on the substrate are often adjacent inside the cable, too. Thus, there is a case of being strongly influenced by the crosstalk.
SUMMARY OF THE INVENTION
One aspect of the present invention relates to a signal transmission cable. The signal transmission cable comprises a terminal part attachable to and detachable from an external device, and a cable fixed to the terminal part at its end. The cable includes a plurality of metal wires configuring signal transmission lines of eight or more channels. The terminal part includes a substrate that includes a plurality of connection parts that are electrically connectable to the external device and connected respectively to the metal wires. The metal wires that are adjacently connected at the plurality of connection parts and configure mutually different signal transmission lines are arranged so as not to be adjacent to each other inside the cable.
Further, a signal transmission cable relating to another aspect of the present invention comprises a terminal part attachable to and detachable from an external device and a cable fixed to the terminal part at its end. The cable includes a plurality of metal wires configuring signal transmission lines of eight or more channels. The terminal part includes a substrate that includes a plurality of connection parts that are electrically connectable to the external device, and a signal processing circuit having a plurality of first terminals connected respectively to the plurality of connection parts, and a plurality of second terminals connected respectively to the metal wires. The metal wires that are adjacently connected at the plurality of second terminals and configure mutually different signal transmission lines are arranged so as not to be adjacent to each other inside the cable.
Further, a signal transmission cable relating to another aspect of the present invention comprises a terminal part attachable to and detachable from an external device and a cable fixed to the terminal part. The cable includes a plurality of metal wires configuring signal transmission lines of eight or more channels. The metal wires include outer metal wires arranged along an periphery of the cable, and inner metal wires arranged on an inner of the outer metal wire. The metal wires that are the outer metal wires and transmit signals in the same direction are arranged so as not to be adjacent to each other.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram illustrating a configuration of a signal transmission cable relating to a first embodiment;
FIG. 2 is a diagram illustrating details of terminal part peripheries;
FIG. 3A is a top view viewing a substrate from one plate surface side;
FIG. 3B is a rear view viewing the substrate from the other plate surface side;
FIG. 4 is a schematic diagram illustrating a configuration viewed from an extending direction at one end of a cable;
FIG. 5A is a top view viewing a substrate relating to a comparative example from one plate surface side;
FIG. 5B is a rear view viewing the substrate relating to the comparative example from the other plate surface side;
FIG. 6 is a schematic diagram illustrating one end of a cable relating to the comparative example;
FIG. 7A is a top view viewing a substrate relating to a second embodiment from one plate surface side;
FIG. 7B is a rear view viewing the substrate relating to the second embodiment from the other plate surface side;
FIG. 8 is a schematic diagram illustrating one end of a cable relating to a third embodiment;
FIG. 9A is a schematic diagram illustrating a metal wire included in a cable relating to a fourth embodiment;
FIG. 9B is a schematic diagram illustrating one end of the cable relating to the fourth embodiment;
FIG. 10A is a top view viewing a substrate relating to a fifth embodiment from one plate surface side;
FIG. 10B is a rear view viewing the substrate relating to the fifth embodiment from the other plate surface side;
FIG. 11A is a schematic diagram illustrating a metal wire included in a cable relating to a fifth embodiment; and
FIG. 11B is a schematic diagram illustrating one end of the cable relating to the fifth embodiment.



DESCRIPTION OF EMBODIMENTS
Description of Embodiments of the Present Invention
(1) One aspect of the present invention relates to a signal transmission cable. The signal transmission cable comprises a terminal part attachable to and detachable from an external device, and a cable fixed to the terminal part at its end. The cable includes a plurality of metal wires configuring signal transmission lines of eight or more channels. The terminal part includes a substrate that includes a plurality of connection parts that are electrically connectable to the external device and connected respectively to the metal wires. The metal wires that are adjacently connected at the plurality of connection parts and configure mutually different signal transmission lines are arranged so as not to be adjacent to each other inside the cable. Thus, the metal wires configuring the different signal transmission lines are prevented from being adjacent both at the connection part and inside the cable. Therefore, influence of crosstalk between the different channels can be reduced.
(2) A signal transmission cable relating to another aspect of the present invention comprises a terminal part attachable to and detachable from an external device and a cable fixed to the terminal part at its end. The cable includes a plurality of metal wires configuring signal transmission lines of eight or more channels. The terminal part includes a substrate that includes a plurality of connection parts that are electrically connectable to the external device, and a signal processing circuit having a plurality of first terminals connected respectively to the plurality of connection parts, and a plurality of second terminals connected respectively to the metal wires. The metal wires that are adjacently connected at the plurality of second terminals and configure mutually different signal transmission lines are arranged so as not to be adjacent to each other inside the cable. Thus, the metal wires configuring the different signal transmission lines are prevented from being adjacent both on the substrate (second terminals) and inside the cable. Therefore, the influence of the crosstalk between the different channels can be reduced also in the signal transmission cable including the signal processing circuit.
(3) In the above-described signal transmission cable, the cable may include outer metal wires arranged along an periphery of the cable, and inner metal wires arranged on an inner of the outer metal wire, as the metal wires. Part of combinations of the metal wires that are adjacently connected at the plurality of connection parts and configure mutually different signal transmission lines may be the combination of the outer metal wires with each other, and the metal wires relating to the combination may be arranged on the same straight line passing through the center of the cable in the cross section of the cable perpendicular to the axis of the cable. Thus, the metal wires that are adjacently connected at the connection parts and configure the mutually different signal transmission lines can be arranged in a more separated positional relation, and the influence of the crosstalk can be more effectively reduced.
(4) In the above-described signal transmission cable, the cable may include outer metal wires arranged along an periphery of the cable, and inner metal wires arranged on an inner of the outer metal wire, as the metal wires. Part of combinations of the metal wires that are adjacently connected at the plurality of second terminals and configure mutually different signal transmission lines may be the combination of the outer metal wires with each other. The metal wires relating to the combination may be arranged on the same straight line passing through the center of the cable in the cross section of the cable perpendicular to the axis of the cable. Thus, the metal wires that are adjacently connected at the second terminals and configure the mutually different signal transmission lines can be arranged in a more separated positional relation, and the influence of the crosstalk can be more effectively reduced.
(5) In the above-described signal transmission cable, the signal processing circuit may transmit or receive differential signals to/from the external device, and may transmit or receive single end signals to/from the metal wires. Since transmission signals or reception signals of the individual channels can be transmitted by one wire, transmission loss due to skew occurrence can be suppressed by using a single wire cable such as a coaxial cable for example.
(6) In the above-described signal transmission cable, the terminal part may have an aligning mold that converts an arrangement of the metal wires inside the cable to an arrangement of the metal wires on the substrate. Thus, the arrangement of the metal wires differently arranged inside the cable and on the substrate can be appropriately converted, and mountability is improved.
(7) A signal transmission cable relating to another aspect of the present invention comprises a terminal part attachable to and detachable from an external device, and a cable fixed to the terminal part at its end. The cable includes a plurality of metal wires configuring signal transmission lines of eight or more channels. The metal wires include outer metal wires arranged along an periphery of the cable, and inner metal wires arranged on an inner of the outer metal wire. The metal wires that are the outer metal wires and transmit signals in the same direction are arranged so as not to be adjacent to each other. While pursuing extensive studies, the present inventors have obtained knowledge that Far End Crosstalk (FEXT) to be a problem between the metal wires relating to signals transmitted in the same direction becomes a problem particularly in the case that the metal wires are adjacent near the periphery of the cable. On one aspect of the present invention, since the metal wires that transmit signals in the same direction are not adjacent to each other on the periphery of the cable, the influence of the FEXT can be reduced.
Details of Embodiments of the Claimed Invention
Specific examples of the signal transmission cable relating to the embodiments of the present invention will be described with reference to the drawings below. The present invention is not limited to these examples and is indicated by the scope of claims, and it is intended to include all modifications within the meanings and scope that are equivalent to the scope of claims. In the following description, the same signs are attached to the same elements in the description of the drawings, and redundant description is omitted.
First Embodiment
FIG. 1 is a diagram illustrating a configuration of a signal transmission cable 1 relating to the first embodiment. As illustrated in FIG. 1, the signal transmission cable 1 of the present embodiment includes two terminal parts 10 and a cable bundle 20 (cable). One terminal part 10 is attached to one end of the cable bundle 20, and the other terminal part 10 is attached to the other end of the cable bundle 20. The cable bundle 20 is formed by bundling a plurality of metal wires 21 that are insulated wires or coaxial cables which transmit signals. Two metal wires 21 form a pair, and two or more pairs of the metal wires 21 are connected to a substrate 13 (details will be described later) of the terminal part 10. Then, a signal transmission line is configured for each pair of the metal wires 21, and digital signals are transmitted by a differential signal transmission system. The cable bundle 20 is formed by bundling the metal wires 21 of four channels each for transmission and reception, that is, the total of eight channels (eight pairs) (details will be described later).
One terminal part 10 can be inserted and removed (attached and detached) to/from an external device 101, and is electrically connected with the external device 101 by being inserted to the external device 101. The other terminal part 10 can be inserted and removed to/from a different external device 102, and is electrically connected with the external device 102 by being inserted to the external device 102.
FIG. 2 is a diagram illustrating details of the periphery of the terminal part 10. As illustrated in FIG. 2, the terminal part 10 includes a metal housing 11. One end of the cable bundle 20 and the substrate 13 are housed inside the metal housing 11, and ends of the metal wires 21 are fixed to the terminal part 10 by soldering the metal wires 21 of the cable bundle 20 to the substrate 13.
FIG. 3A is a top view viewing the substrate 13 from one plate surface side. FIG. 3B is a rear view viewing the substrate 13 from the other plate surface side. As illustrated in FIGS. 3A and 3B, the substrate 13 presents a rectangular shape having a longitudinal direction and a short direction, and includes a dielectric substrate, and conductive wiring patterns formed on one surface 13a and on the other surface 13b of the dielectric substrate. The substrate 13 has a connection part 12 and a pad group 15, and is electrically connectable to the external devices 101 and 102 and the metal wires 21.
The connection part 12 configures an electrical interface with the external devices 101 and 102 (see FIG. 1 and FIG. 2). The connection part 12 includes a plurality of terminals 12a-12p (a plurality of connection parts) provided on one surface 13a and the other surface 13b. The plurality of terminals 12a-12p are provided corresponding to each of the metal wires 21 of the individual channels included in the cable bundle 20, and are connected respectively to the individual metal wires. For the plurality of terminals 12a-12p, a pair of terminals is configured by two terminals, and a pair of terminals 12e and 12f, a pair of terminals 12g and 12h, a pair of terminals 12i and 12j, and a pair of terminals 12k and 12l are signal terminals for transmission. A pair of terminals 12a and 12b, a pair of terminals 12c and 12d, a pair of terminals 12m and 12n, and a pair of terminals 12o and 12p are signal terminals for reception. In FIGS. 3A and 3B, terminals other than the terminals 12a-12p that are the signal terminals, a power supply terminal and a ground terminal or the like for example, are omitted.
On one surface 13a, a pair of the terminals 12c and 12d and a pair of the terminals 12e and 12f are arranged so as to be between a pair of the terminals 12a and 12b and a pair of the terminals 12g and 12h, and more specifically, a pair of the terminals 12c and 12d is arranged at a position near a pair of the terminals 12a and 12b between a pair of the terminals 12a and 12b and a pair of the terminals 12g and 12h, and a pair of the terminals 12e and 12f is arranged at a position near a pair of the terminals 12g and 12h between a pair of the terminals 12a and 12b and a pair of the terminals 12g and 12h. That is, a pair of the terminals 12a and 12b is adjacent to a pair of the terminals 12c and 12d, a pair of the terminals 12c and 12d is adjacent to a pair of the terminals 12a and 12b and a pair of the terminals 12e and 12f, a pair of the terminals 12e and 12f is adjacent to a pair of the terminals 12c and 12d and a pair of the terminals 12g and 12h, and a pair of the terminals 12g and 12h is adjacent to a pair of the terminals 12e and 12f. 
On the other surface 13b, a pair of the terminals 12k and 12l and a pair of the terminals 12m and 12n are arranged so as to be between a pair of the terminals 12i and 12j and a pair of the terminals 12o and 12p, and more specifically, a pair of the terminals 12k and 12l is arranged at a position near a pair of the terminals 12i and 12j between a pair of the terminals 12i and 12j and a pair of the terminals 12o and 12p, and a pair of the terminals 12m and 12n is arranged at a position near a pair of the terminals 12o and 12p between a pair of the terminals 12i and 12j and a pair of the terminals 12o and 12p. That is, a pair of the terminals 12i and 12j is adjacent to a pair of the terminals 12k and 12l, a pair of the terminals 12k and 12l is adjacent to a pair of the terminals 12i and 12j and a pair of the terminals 12m and 12n, a pair of the terminals 12m and 12n is adjacent to a pair of the terminals 12k and 12l and a pair of the terminals 12o and 12p, and a pair of the terminals 12o and 12p is adjacent to a pair of the terminals 12m and 12n. 
The pad group 15 includes a pad group 15A provided on one surface 13a of the substrate 13 and a pad group 15B provided on the other surface lab of the substrate 13. Each of the pad groups 15A and 15B has four pads 15a for transmission and four pads 15b for reception. To the pad 15a, one end of a core wire 21a of the metal wires 26-29 which are the metal wires 21 for the transmission and configure the mutually different signal transmission lines is conductively bonded. Further, to the pad 15b, one end of a core wire 21a of the metal wires 22-25 which are the metal wires 21 for the reception and configure the mutually different signal transmission lines is conductively bonded.
The pad 15a to which a pair of metal wires 26a and 26b configuring the metal wire 26 for the transmission is conductively bonded is electrically connected to a pair of the terminals 12g and 12h through wiring 16. The pad 15a to which a pair of metal wires 28a and 28b configuring the metal wire 28 for the transmission is conductively bonded is electrically connected to a pair of the terminals 12e and 12f through the wiring 16. The pal 15a to which a pair of metal wires 27a and 27b configuring the metal wire 27 for the transmission is conductively bonded is electrically connected to a pair of the terminals 12i and 12j through the wiring 16. The pad 15a to which a pair of metal wires 29a and 29b configuring the metal wire 29 for the transmission is conductively bonded is electrically connected to a pair of the terminals 12k and 12l through the wiring 16.
The pad 15b to which a pair of metal wires 25a and 25b configuring the metal wire 25 for the reception is conductively bonded is electrically connected to a pair of the terminals 12c and 12d through the wiring 16. The pad 15b to which a pair of metal wires 23a and 23b configuring the metal wire 23 for the reception is conductively bonded is electrically connected to a pair of the terminals 12a and 12b through the wiring 16. The pad 15b to which a pair of metal wires 24a and 24b configuring the metal wire 24 for the reception is conductively bonded is electrically connected to a pair of the terminals 12m and 12n through the wiring 16. The pad 15b to which a pair of metal wires 22a and 22b configuring the metal wire 22 for the reception is conductively bonded is electrically connected to a pair of the terminals 12o and 12p through the wiring 16.
Thus, at the connection part 12 on one surface 13a, a pair of the metal wires 26a and 26b electrically connected to a pair of the terminals 12g and 12h and a pair of the metal wires 28a and 28b electrically connected to a pair of the terminals 12e and 12f are adjacently connected. A pair of the metal wires 28a and 28b electrically connected to a pair of the terminals 12e and 12f and a pair of the metal wires 25a and 25b electrically connected to a pair of the terminals 12c and 12d are adjacently connected. A pair of the metal wires 25a and 25b electrically connected to a pair of the terminals 12c and 12d and a pair of the metal wires 23a and 23b electrically connected to a pair of the terminals 12a and 12b are adjacently connected.
Further, at the connection part 12 on the other surface 13b, a pair of the metal wires 27a and 27b electrically connected to a pair of the terminals 12i and 12j and a pair of the metal wires 29a and 29b electrically connected to a pair of the terminals 12k and 12l are adjacently connected. A pair of the metal wires 29a and 29b electrically connected to a pair of the terminals 12k and 12l and a pair of the metal wires 24a and 24b electrically connected to a pair of the terminals 12m and 12n are adjacently connected. A pair of the metal wires 24a and 24b electrically connected to a pair of the terminals 12m and 12n and a pair of the metal wires 22a and 22b electrically connected to a pair of the terminals 12o and 12p are adjacently connected.
FIG. 4 is a schematic diagram illustrating a configuration viewed from an extending direction at one end of the cable bundle 20. The cable bundle 20 includes the plurality of metal wires 22-29 that transmit signals, and a coating part 30 that covers the metal wires 22-29. The coating part 30 has a jacket configured by an insulator such as polyvinyl chloride, polyester, urethane or rubber, and a braided wire (external conductor) that is interposed between the jacket and the metal wires 22-29 and covers the metal wires 22-29.
The cable bundle 20 includes, as the metal wires 21, the outer metal wires arranged along the periphery of the cable bundle 20, and the inner metal wires arranged on the inner of the outer metal wires. Specifically, the metal wires 22, 24, 25, 27, 28 and 29 are the outer metal wires arranged along the periphery of the cable bundle 20, and the metal wires 23 and 26 are the inner metal wires arranged on the inner of the outer metal wires. In the cable bundle 20, inclusions 31 are arranged so as to be adjacent to the inner metal wires on the inner of the outer metal wires.
In the cable bundle 20, the metal wires that are adjacently connected at the connection part 12 of the substrate 13 described above and configure the mutually different signal transmission lines are arranged so as not to be adjacent to each other inside the cable bundle 20. Since the metal wires configure the individual signal transmission line by a pair (two wires), the fact that the metal wires of the different signal transmission lines are not adjacent to each other inside the cable bundle 20 means that both of the two wires of a pair are not adjacent to each other. That is, the fact that a first metal wire and a second metal wire are not adjacent to each other means that both of a pair (two) of the metal wires which are the first metal wires are not adjacent to either of a pair (two) of the metal wires which are the second metal wires.
Description will be given specifically with reference to FIGS. 3A, 3B and FIG. 4. For example, the metal wires 26 (metal wires 26a and 26b) and the metal wires 28 (metal wires 28a and 28b) are adjacently connected at the connection part 12. On the other hand, inside the cable bundle 20, the inclusion 31 and the metal wires 23 (R2-1 and R2-2 illustrated in FIG. 4) are arranged between the metal wires 26 (T1-1 and T1-2 in FIG. 4) and the metal wires 28 (T3-1 and T3-2 illustrated in FIG. 4), and the metal wires 26 and the metal wires 28 are not arranged adjacently to each other. Similarly, the metal wires 28 (metal wires 28a and 28b) and the metal wires 25 (metal wires 25a and 25b) adjacently connected at the connection part 12 are not arranged adjacently to each other inside the cable bundle 20 (see the metal wires 28 (T3-1 and T3-2) and the metal wires 25 (R4-1 and R4-2) in FIG. 4). Similarly, the metal wires 25 (metal wires 25a and 25b) and the metal wires 23 (metal wires 23a and 23b) adjacently connected at the connection part 12 are not arranged adjacently to each other inside the cable bundle 20 (see the metal wires 25 (R4-1 and R4-2) and the metal wires 23 (R2-1 and R2-2) in FIG. 4). Similarly, the metal wires 27 (metal wires 27a and 27b) and the metal wires 29 (metal wires 29a and 29b) adjacently connected at the connection part 12 are not arranged adjacently to each other inside the cable bundle 20 (see the metal wires 27 (T2-1 and T-2) and the metal wires 29 (T4-1 and T4-2) in FIG. 4). Similarly, the metal wires 29 (metal wires 29a and 29b) and the metal wires 24 (metal wires 24a and 24b) adjacently connected at the connection part 12 are not arranged adjacently to each other inside the cable bundle 20 (see the metal wires 29 (T4-1 and T4-2) and the metal wires 24 (R3-1 and R3-2) in FIG. 4). Similarly, the metal wires 24 (metal wires 24a and 24b) and the metal wires 22 (metal wires 22a and 22b) adjacently connected at the connection part 12 are not arranged adjacently to each other inside the cable bundle 20 (see the metal wires 24 (R3-1 and R3-2) and the metal wires 22 (R1-1 and R1-2) in FIG. 4).
Further, in the cable bundle 20, part of the combinations of the metal wires that are adjacently connected at the connection part 12 of the substrate 13 and configure the mutually different signal transmission lines is the combination of the outer metal wires with each other, and the metal wires 21 relating to the combination are arranged on the same straight line SL passing through the center of the cable bundle 20 in the cross section of the cable bundle 20 perpendicular to the axis of the cable bundle 20. For example, the combination of the metal wires 28 and the metal wires 25 that are adjacently connected at the connection part 12 and configure the mutually different signal transmission lines is the combination of the outer metal wires with each other, and the metal wires 28 and 25 relating to the combination are arranged on the same straight line SL passing through the center of the cable bundle 20 in the cross section of the cable bundle 20 perpendicular to the axis of the cable bundle 20.
As described above, since the arrangement of the metal wires 21 inside the cable bundle 20 and the arrangement of the metal wires 21 at the connection part 12 are different, the terminal part 10 may have an aligning mold 70 (see FIGS. 3A and 3B) that converts the arrangement of the metal wires inside the cable bundle 20 to the arrangement of the metal wires 21 on the substrate 13 (at the connection part 12 more specifically). The aligning mold 70 is in a roughly cubic shape molded with plastic or polycarbonate or the like as a material, and is arranged on the side of the cable bundle 20 (on the opposite side of the connection part 12) to the pad group 15. On the aligning mold 70, an opening of the absolute minimum size that the metal wire 21 can pass through is formed. Or, the metal wires 21 are fixed by the aligning mold 70. By the metal wires 21 passing through the opening or being fixed by the mold after being aligned, the metal wires 21 are aligned and the metal wires 21 are easily connected at the connection part 12.
Effects obtained by the signal transmission cable 1 of the present embodiment including the above configuration will be described.
Generally, the line (wiring pattern) of the terminals on the substrate of the terminal part is determined by a standard. From that, the metal wires inside the cable are generally arranged based on the line of the terminals on the substrate in consideration of the mountability to the substrate.
Here, FIG. 5A is a top view viewing the substrate relating to a comparative example from one plate surface side. FIG. 5B is a rear view viewing the substrate relating to the comparative example from the other plate surface side. FIG. 6 is a schematic diagram illustrating one end of the cable relating to the comparative example. In the comparative example, the pad 15a to which a pair of metal wires 260a and 260b configuring a metal wire 260 for the transmission are conductively bonded is electrically connected to a pair of the terminals 12g and 12h through the wiring 16. The pad 15a to which a pair of metal wires 280a and 280b configuring a metal wire 280 for the transmission are conductively bonded is electrically connected to a pair of the terminals 12e and 12f through the wiring 16. The pad 15a to which a pair of metal wires 270a and 270b configuring a metal wire 270 for the transmission are conductively bonded is electrically connected to a pair of the terminals 12i and 12j through the wiring 16. The pad 15a to which a pair of metal wires 290a and 290b configuring a metal wire 290 for the transmission are conductively bonded is electrically connected to a pair of the terminals 12k and 12l through the wiring 16.
Further, in the comparative example, the pad 15b to which a pair of metal wires 250a and 250b configuring a metal wire 250 for the reception are conductively bonded is electrically connected to a pair of the terminals 12c and 12d through the wiring 16. The pad 15b to which a pair of metal wires 230a and 230b configuring a metal wire 230 for the reception are conductively bonded is electrically connected to a pair of the terminals 12a and 12h through the wiring 16. The pad 15b to which a pair of metal wires 240a and 240b configuring a metal wire 240 for the reception are conductively bonded is electrically connected to a pair of the terminals 12m and 12n through the wiring 16. The pad 15b to which a pair of metal wires 220a and 220b configuring a metal wire 220 for the reception are conductively bonded is electrically connected to a pair of the terminals 12o and 12p through the wiring 16.
For example, in the comparative example, the metal wire 260 for the transmission and the metal wire 280 for the transmission adjacently connected at the connection part 12 are also arranged adjacently to each other inside, a cable bundle 200 (see the metal wire 260a (T1-1) and the metal wire 280b (T3-2) in FIG. 6). In the case that the metal wires that transmit signals in the same direction are adjacent both inside the cable and at the connection part in this way, the Far End Crosstalk (FEXT) which occurs between the signals in the same direction becomes particularly remarkable. Further, the metal wire 280 for the transmission and the metal wire 250 for the reception adjacently connected at the connection part 12 are also arranged adjacently to each other inside the cable bundle 200 (see the metal wire 280a (T3-1) and the metal wire 250b (R4-2) in FIG. 6). In the case that the metal wires that transmit signals in the different directions are adjacent both inside the cable and at the connection part in this way, Near End Crosstalk (NEXT) which occurs between transmission signals and reception signals becomes particularly remarkable. From the above, when the metal wires configuring the different signal transmission lines are adjacent both at the connection part and inside the cable, the influence of the crosstalk becomes remarkable.
In this respect, in the signal transmission cable 1 relating to the present embodiment, the metal wires 21 that are adjacently connected at the connection part 12 and configure the different signal transmission lines are arranged so as not to be adjacent (that is, through the other metal wire 21) inside the cable bundle 20 (see FIGS. 3A and 3B and FIG. 4). Thus, the metal wires 21 configuring the different signal transmission lines are prevented from being adjacent both at the connection part 12 and inside the cable bundle 20. Therefore, compared to the above-described comparative example, the influence of the crosstalk between the different charnels can be reduced.
Further, the cable bundle 20 includes, as the metal wires 21, the outer metal wires arranged along the periphery of the cable bundle 20, and the inner metal wires arranged on the inner of the outer metal wires, and part of the combinations of the metal wires 21 of the mutually different channels that are adjacently connected at the plurality of connection parts 12 is the combination of the outer metal wires with each other, and the metal wires 21 relating to the combination are arranged on the same straight line SL passing through the center of the cable bundle 20 in the cross section of the cable bundle 20 perpendicular to the axis of the cable bundle 20. Thus, the metal wires that are adjacently connected at the connection part 12 and configure the different signal transmission lines can be arranged in a more separated positional relation in the cable bundle 20, and the influence of the crosstalk can be more effectively reduced. It is preferable that the combination is the combination of the metal wire 21 for the transmission and the metal wire 21 for the reception. Thus, the NEXT can be effectively reduced.
Further, since the terminal part 10 includes the aligning mold 70 that converts the arrangement of the metal wires 21 inside the cable bundle 20 to the arrangement of the metal wires 21 on the substrate 13, the arrangement of the metal wires 21 differently arranged inside the cable bundle 20 and at the connection part 12 can be appropriately converted, and the mountability is improved.
Second Embodiment
FIG. 7A is a top view viewing a substrate 13x relating to the second embodiment from one plate surface side. FIG. 7B is a rear view viewing the substrate 13x relating to the second embodiment from the other plate surface side. In the description of the second embodiment, the description in common with the first embodiment is omitted. It is similar in third-fifth embodiments described later. As illustrated in FIGS. 7A and 7B, the substrate 13x is similar to the above-described substrate 13 in that it has the connection part 12 and the pad group 15, but is different in that it is mounted with a signal processing circuit 120. The signal processing circuit 120 includes a signal shaping circuit such as a clock data recovery (CDR) circuit or a repeater circuit, and the signal shaping circuit is configured by an integrated circuit element (IC). The signal processing circuit 120 is electrically connected with an internal circuit of the external device by inserting the terminal part to the external device. The signal processing circuit 120 has a plurality of first terminals 121a-121p connected respectively to the plurality of terminals 12a-12p through wiring 16b, and second terminals 122a-122p connected respectively to the metal wires 22-29 of the individual channels through wiring 16a. 
In more detail, the pad 15a to which a pair of the metal wires 26a and 26b configuring the metal wire 26 for the transmission is conductively bonded is electrically connected to a pair of the terminals 12g and 12h through the wiring 16a, second terminals 122g and 122h and first terminals 121g and 121h of the signal processing circuit 120 and the wiring 16b. The pad 15a to which a pair of the metal wires 28a and 28b configuring the metal wire 28 for the transmission is conductively bonded is electrically connected to a pair of the terminals 12e and 12f through the wiring 16a, second terminals 122e and 122f and first terminals 121e and 121f of the signal processing circuit 120 and the wiring 16b. The pad 15a to which a pair of the metal wires 27a and 27b configuring the metal wire 27 for the transmission is conductively bonded is electrically connected to a pair of the terminals 12i and 12j through the wiring 16a, second terminals 122i and 122j and first terminals 121i and 121j of the signal processing circuit 120 and the wiring 16b. The pad 15a to which a pair of the metal wires 29a and 29b configuring the metal wire 29 for the transmission is conductively bonded is electrically connected to a pair of the terminals 12k and 12l through the wiring 16a, second terminals 122k and 122l and first terminals 121k and 121l of the signal processing circuit 120 and the wiring 16b. 
The pad 15b to which a pair of the metal wires 25a and 25b configuring the metal wire 25 for the reception is conductively bonded is electrically connected to a pair of the terminals 12c and 12d through the wiring 16a, the second terminals 122c and 122d and first terminals 121c and 121d of the signal processing circuit 120 and the wiring 16b. The pad 15b to which a pair of the metal wires 23a and 23h configuring the metal wire 23 for the reception is conductively bonded is electrically connected to a pair of the terminals 12a and 12b through the wiring 16a, second terminals 122a and 122b and first terminals 121a and 121b of the signal processing circuit 120 and the wiring 16b. The pad 15b to which a pair of the metal wires 24a and 24b configuring the metal wire 24 for the reception is conductively bonded is electrically connected to a pair of the terminals 12m and 12n through the wiring 16a, second terminals 122m and 122n and first terminals 121m and 121n of the signal processing circuit 120 and the wiring 16b. The pad 15b to which a pair of the metal wires 22a and 22b configuring the metal wire 22 for the reception is conductively bonded is electrically connected to a pair of the terminals 12o and 12p through the wiring 16a, second terminals 122o and 122p and first terminals 121o and 121p of the signal processing circuit 120 and the wiring 16b. 
The arrangement of the metal wires 21 of the cable bundle 20 in the present embodiment is like FIG. 4 similarly to the first embodiment, and the metal wires that are adjacently connected at the second terminals 122a-122p and configure the mutually different signal transmission lines are arranged so as not to be adjacent to each other inside the cable bundle 20. Thus, similarly to the first embodiment, the influence of the crosstalk between the different channels can be reduced. Since the arrangement of the metal wires 21 in the cable bundle 20 is similar to the first embodiment, part of the combinations of the metal wires 21 adjacently connected at the second terminals 122a-122p is the combination of the outer metal wires with each other, and the metal wires 21 relating to the combination are arranged on the same straight line passing through the center of the cable bundle 20 in the cross section of the cable bundle 20 perpendicular to the axis of the cable bundle 20. Thus, the influence of the crosstalk can be reduced more.
Third Embodiment
FIG. 8 is a schematic diagram illustrating one end of a cable bundle 20A relating to the third embodiment. As illustrated in FIG. 8, the cable bundle 20A has, as the outer metal wires arranged along the periphery of the cable bundle 20A, metal wires 47a and 47b (T2-1 and T2-2 in FIG. 8), metal wires 48a and 48b (T3-1 and T3-2 in FIG. 8) and metal wires 49a and 49b (T4-1 and T4-2 in FIG. 8) which are the metal wires for the transmission. The cable bundle 20A has, as the outer metal wires arranged along the periphery of the cable bundle 20A, metal wires 42a and 42b (R1-1 and R1-2 in FIG. 8), metal wires 44a and 44b (R3-1 and R3-2 in FIG. 8) and metal wires 45a and 45b (R4-1 and R4-2 in FIG. 8) which are the metal wires for the reception. The cable bundle 20A has, as the inner metal wires arranged on the inner of the outer metal wires, metal wires 46a and 46b (T1-1 and T1-2 in FIG. 8) which are the metal wires for the transmission, and metal wires 43a and 43b (R2-1 and R2-2 in FIG. 8) which are the metal wires for the reception.
In the cable bundle 20A, the metal wires that are the outer metal wires and transmit signals in the same direction are arranged so as not to be adjacent to each other on the periphery of the cable bundle 20A. Specifically, on the periphery of the cable bundle 20A, the metal wires of a differential pair configuring the same signal transmission line are not adjacent. Then, between the metal wires of the differential pair, the metal wire that transmits signals in the direction opposite to the metal wires of the differential pair is arranged. For example, between the metal wires 42a and 42b which are the differential pair that are arranged along the periphery of the cable bundle 20A and configure the signal transmission line for the reception, the metal wire 49a which is the metal wire for the transmission is arranged. In this way, in the cable bundle 20A, on the periphery of the cable bundle 20A, the metal wires that transmit signals in the same direction are arranged so as not to be adjacent to each other.
The FEXT to be a problem between the signal transmission lines that transmit signals in the same direction becomes a problem particularly in the case that the metal wires configuring the signal transmission lines are adjacent near the periphery of the cable. Thus, in the cable bundle 20A, since the metal wires 21 that transmit signals in the same direction are not adjacent to each other on the periphery of the cable bundle 20A, the influence of the FEXT can be reduced.
Fourth Embodiment
FIG. 9A is a schematic diagram illustrating one cable core 50 (metal wire) included in a cable bundle 20B, and FIG. 9B is a schematic diagram illustrating one end of the entire cable bundle 20B. As illustrated in FIG. 9A, the cable core 50 is a twin-ax cable. One cable core 50 included in the cable bundle 20B has a pair of conductors 50a arranged in parallel. Then, on respective outer peripheral surfaces of the pair of conductors 50a, a pair of coating layers 50b is provided respectively by extrusion molding. The coating layer 50b is configured by a foamed insulating resin or the like. Then, shields 50c and 50d surround the periphery of the coating layers 50b, and a jacket 50e surrounds the periphery further.
The cable bundle 20B has cable cores 51-58 as the cable cores 50. The cable cores 51-54 are the metal wires for the reception, and the cable cores 55-58 are the metal wires for the transmission. In the present embodiment as well, the metal wires (cable cores 51-58) of the different channels that are adjacently connected at the connection part of the substrate are arranged so as not to be adjacent to each other inside the cable bundle 20B. That is, for example, in the case that the cable core 51 is adjacent to the cable core 53 at the connection part of the substrate, as illustrated in FIG. 9B, the cable core 51 (R1 in FIG. 9B) and the cable core 53 (R3 in FIG. 9B) are arranged so as not to be adjacent. By such an arrangement, even in the case of using the twin-ax cable as the cable bundle, similarly to the first embodiment, the influence of the crosstalk between the different channels can be reduced.
Fifth Embodiment
FIG. 10A is a top view viewing a substrate 13y relating to the fifth embodiment from one plate surface side, and FIG. 10B is a rear view viewing the substrate 13y relating to the fifth embodiment from the other plate surface side. FIG. 11A is a schematic diagram illustrating one metal wire included in a cable bundle 20C, and FIG. 11B is a schematic diagram illustrating one end of the entire cable bundle 20C. As illustrated in FIG. 11B, the cable bundle 20C is a coaxial cable for single end input. A metal wire 60 included in the cable bundle 20C is the metal wire that transfers data by one signal line, and includes an internal conductor 60a, an insulator 60b provided on an outer peripheral surface of the internal conductor 60a, external conductors 60c and 60d surrounding the periphery of the insulator 60b, and a jacket 60e surrounding the periphery of the external conductor 60d. The cable bundle 20C has metal wires 61-68 as the metal wires 60.
As illustrated in FIGS. 10A and 10B, the substrate 13y is mounted with a signal processing circuit 120y. Similarly to the above-described signal processing circuit 120, the signal processing circuit 120y includes a signal shaping circuit such as a clock data recovery (CDR) circuit or a repeater circuit, and the signal shaping circuit is configured by an integrated circuit element (IC). The signal processing circuit 120y transmits or receives differential signals to/from the external device, and also transmits or receives single end signals to/from the metal wires 61-68. The signal processing circuit 120y has a pair of terminals 128 corresponding to each of the individual metal wires 61-68. At one terminal 128a of a pair of the terminals 128, one of the metal wires 61-68 is short-circuited in terms of AC and the single end signals are transmitted and received. On the other hand, the other terminal 128b is terminated.
In the above-described cable bundle 20C which is the coaxial cable for the single end input as well, the metal wires 61-68 of the mutually different channels that are adjacently connected at the terminal 128 (the terminal 128a more specifically) of the signal processing circuit 120y are arranged so as not to be adjacent to each other inside the cable bundle 20C. That is, for example, as illustrated in FIG. 10A, the metal wires 65 and 67 that are adjacently connected at the terminal 128 are arranged so as not to be adjacent to each other inside the cable bundle 20C as illustrated in FIG. 11B (see T1 and T3 in FIG. 11B). By such an arrangement, even in the case of using the coaxial cable for the single end input as the cable bundle, similarly to the first embodiment, the influence of the crosstalk between the different channels can be reduced. By using the coaxial cable for the single end input, the transmission signals and the reception signals can be transmitted by one wire so that transmission loss due to skew occurrence can be suppressed.
The embodiments of the present invention are described above, however, the present invention is not limited to the above-described embodiments. For example, the metal wires 21 configuring the signal transmission lines included in the cable bundle 20 are described as eight channels, however, without being limited thereto, the number of channels may be larger than eight channels. Further, as a configuration for converting the differential signals to the single end signals, a system of connecting one of differential output of the integrated circuit element to a terminating circuit is illustrated, however, as a system for converting the differential signals to the single end signals, various systems can be adopted without being limited thereto.

## Claims

1. A signal transmission cable comprising:
a terminal part attachable to and detachable from an external device; and
a cable fixed to the terminal part at its end,
wherein the cable includes a plurality of metal wires configuring signal transmission lines of eight or more channels,
wherein the terminal part comprises a substrate that includes a plurality of connection parts that are electrically connectable to the external device and connected respectively to the metal wires, and
wherein any two of the metal wires that are connected directly adjacent at the plurality of connection parts and configure mutually different signal transmission lines are arranged so as not to be directly adjacent to each other inside the cable; wherein the cable includes outer metal wires arranged along an periphery of the cable, and inner metal wires arranged on an inner of the outer metal wire, as the metal wires, and wherein part of combinations of the metal wires that are adjacently connected directly adjacent at the plurality of second terminals and configure mutually different signal transmission lines is the combination of the outer metal wires with each other, and the metal wires relating to the combination are arranged on the same straight line passing through the center of the cable in the cross section of the cable perpendicular to the axis of the cable.

2. The signal transmission cable according to claim 1,
wherein the terminal part has an aligning mold that converts an arrangement of the metal wires inside the cable to an arrangement of the metal wires on the substrate.

3. A signal transmission cable comprising: a terminal part attachable to and detachable from an external device; and a cable fixed to the terminal part at its end, wherein the cable includes a plurality of metal wires configuring signal transmission lines of eight or more channels, wherein the terminal part comprises a substrate that includes: a plurality of connection parts that are electrically connectable to the external device, and a signal processing circuit having a plurality of first terminals connected respectively to the plurality of connection parts, and a plurality of second terminals connected respectively to the metal wires, and wherein any two of the metal wires that are adjacently connected directly adjacent at the plurality of second terminals and configure mutually different signal transmission lines are arranged so as not to be directly adjacent to each other inside the cable; wherein the cable includes outer metal wires arranged along an periphery of the cable, and inner metal wires arranged on an inner of the outer metal wire, as the metal wires, and wherein part of combinations of the metal wires that are adjacently connected directly adjacent at the plurality of second terminals and configure mutually different signal transmission lines is the combination of the outer metal wires with each other, and the metal wires relating to the combination are arranged on the same straight line passing through the center of the cable in the cross section of the cable perpendicular to the axis of the cable.

4. The signal transmission cable according to claim 3,
wherein the signal processing circuit transmits or receives differential signals to/from the external device, and transmits or receives single end signals to/from the metal wires.