Shielded cable for high-speed differential communication

Abstract

According to the present invention, a transmission disturbance is suppressed.　This shielded cable (10) for high-speed differential communication is used as a transmission path of a high-speed differential communication circuit, and comprises: two non-shielded-type covered electric wires (12) routed in parallel; and a conductive shielding member (15) disposed between the two covered electric wires (12). Although the covered electric wires (12) themselves do not have a shielding function, since the conductive shielding member (15) is disposed between the two covered electric wires (12), a transmission disturbance between the two covered electric wires (12) is suppressed.

Description

Shielded Cable for High-Speed Differential Communication

[0001] The present disclosure relates to a shielded cable for high-speed differential communication.

[0002] Patent Document 1 discloses a communication shielded cable including a pair of core wires in which a stranded conductor is coated with an insulator, and a shield layer that collectively surrounds the pair of core wires.

[0003] Japanese Unexamined Patent Application Publication No. 2024-137726

[0004] In the above shielded cable, a pair of core wires without a shield layer are arranged in proximity to each other. Therefore, there is a concern that a transmission failure may occur in the pair of core wires due to crosstalk or the like.

[0005] The shielded cable for high-speed differential communication of the present disclosure has been completed based on the above circumstances, and aims to suppress transmission failures.

[0006] The shielded cable for high-speed differential communication of the present disclosure is a shielded cable used as a transmission line for a high-speed differential communication circuit, and includes two non-shielded type coated electric wires arranged in parallel, and a conductive shielding member disposed between the two coated electric wires.

[0007] According to the present disclosure, transmission failures can be suppressed.

[0008] FIG. 1 is a front view of the shielded cable of Example 1. FIG. 2 is a front view of a comparative cable. FIG. 3 is a graph showing the shielding performance of the shielded cable of Example 1 and the comparative cable. FIG. 4 is a front view of the shielded cable of Example 2.

[0009] [Description of Embodiments of the Disclosure] First, embodiments of the Disclosure will be listed and described. Any combination of the following embodiments, to the extent that they do not cause contradictions, is also included as a form for carrying out the invention. The shielded cable for high-speed differential communication of the Disclosure is (1) a shielded cable used as a transmission path for a high-speed differential communication circuit, comprising two unshielded insulated wires arranged in parallel, and a conductive shielding member disposed between the two insulated wires. With this configuration, even if the insulated wires themselves do not have a shielding function, the conductive shielding member is placed between the two insulated wires, so that transmission interference between the two insulated wires is suppressed.

[0010] (2) In (1), it is preferable that the shielding member surrounds one of the insulated wires individually and around its entire circumference. With this configuration, not only transmission interference between the two insulated wires but also noise between the insulated wire and the transmission path other than the insulated wire can be shielded, thus providing excellent shielding performance.

[0011] (3) In (2), it is preferable that the shielding member is made of metal foil only. With this configuration, it is possible to achieve shielding performance equivalent to that when two insulated wires are enclosed together with braided wire.

[0012] (4) In (1), it is preferable that the shielding member is arranged in the form of a partition wall between the two insulated wires, and that the two insulated wires are collectively surrounded by the shielding layer. With this configuration, not only transmission interference between the two insulated wires but also noise between the insulated wires and transmission paths other than the insulated wires can be shielded, thus providing excellent shielding performance.

[0013] [Details of Embodiments of the Disclosure] [Example 1] A shielded cable 10 of Example 1 embodying the present disclosure will be described with reference to Figures 1 to 3. The present invention is not limited to these examples, but is shown in the claims, and all modifications within the meaning and range equivalent to the claims are included. In this Example 1, the vertical direction and the height direction are used synonymously. The left-right direction and the width direction are used synonymously.

[0014] The shielded cable 10 of this embodiment 1 is a shielded cable 10 for high-speed differential communication used as a transmission line for a high-speed differential communication circuit. As shown in Figure 1, the shielded cable 10 is composed of a pair of shielded wires 11 and a sheath 16. Each shielded wire 11 is composed of a single unshielded coated wire 12 and a shielding member 15.

[0015] The insulated wire 12 is composed of one conductor 13 and one insulator 14. The conductor 13 is, for example, made of conductive stranded wire. The insulator 14 is made of an electrically insulating material such as synthetic resin. The insulator 14 concentrically surrounds the conductor 13 all around. The shielding member 15 is a cylindrical member that concentrically surrounds the insulated wire 12 (conductor 13 and insulator 14). The shielding member 15 is formed by wrapping a single metal foil around the outer surface of the insulator 14 (insulated wire 12). The outermost layer of the shielded wire 11 is composed of the shielding member 15.

[0016] The sheath 16 is an insulating cylindrical member made of synthetic resin. The outer circumference of the sheath 16 is perfectly circular. The inner circumference of the sheath 16 is elliptical with its major axis oriented in the left-right direction. The pair of shield wires 11 are routed adjacent to each other in the left-right direction within the sheath 16. Within the sheath 16, both the left and right ends of the outer surface of each shield wire 11 are in contact with the other shield wire 11 and the inner surface of the sheath 16. Since the pair of shield wires 11 are adjacent to each other in the left-right direction, the semi-cylindrical region of the shielding member 15 that constitutes the outermost layer of each shield wire 11 and faces the other shield wire 11 is positioned to be interposed between the pair of insulated wires 12.

[0017] The pair of shielded wires 11 are considered as a pair of Dual-Coax wires and are used as a transmission path for high-speed differential communication. Figure 2 shows a comparison cable 20 for comparison with the shielded cable 10 of this embodiment 1 in terms of shielding performance. The comparison cable 20 is a cable obtained by removing the sheath and braided wire from an STP wire (Shielded Twisted Pair Cable) which has a two-layer shielding structure consisting of metal foil and braided wire. That is, the comparison cable 20 is a cable in which one twisted pair wire 21 is surrounded by metal foil 22. The twisted pair wire 21 is constructed by twisting together two unshielded coated wires 12, each with a conductor 13 surrounded by an insulator 14, in a spiral shape.

[0018] Figure 3 shows a graph of the characteristic value As (Screening Attenuation characteristic) indicating the shielding performance of the shielded cable 10 of this embodiment 1 and the comparison cable 20. In the graph, curve La represents the As value of the shielded cable 10 of this embodiment 1. Curve Lb represents the As value of the comparison cable 20. The graph also shows the OABR standard value Lc. The OABR standard value Lc is the As standard value of the cable described in the communication standard for automotive Ethernet, namely OPEN ALLIANCE 1G (Channel and Component Requirements for 1000BASE-T1 Link Segment Type A (STP)). Note that OABR is a registered trademark.

[0019] As shown in the graph, the As value Lb of the comparison cable 20, in which the braided wire was removed and the two conductors 13 were collectively surrounded by metal foil 22, deteriorated significantly and did not satisfy the OABR standard value Lc. In contrast, the As value La of the shielded cable 10 of this embodiment 1, in which the conductors 13 of each shielded wire 11 are individually covered by conductive shielding members 15, clears the OABR standard value Lc and exhibits superior shielding performance compared to the comparison cable 20.

[0020] The shielded cable 10 for high-speed differential communication in this embodiment 1 comprises two unshielded insulated wires 12 arranged in parallel, and a conductive shielding member 15 placed between the two insulated wires 12. With this configuration, even if the insulated wires 12 themselves do not have a shielding function, the presence of the conductive shielding member 15 between the two insulated wires 12 suppresses transmission interference between the two insulated wires 12.

[0021] The shielding member 15 individually and completely surrounds one insulated wire 12. This configuration provides excellent shielding performance because it can shield not only from transmission interference between the two insulated wires 12 but also from noise between the insulated wires 12 and transmission paths other than the insulated wires 12. The shielding member 15 is made only of metal foil. This configuration provides shielding performance equivalent to that of surrounding the two insulated wires 12 together with braided wire.

[0022] [Example 2] An example 2 of the shielded cable 30 embodying the present disclosure will be described with reference to Figure 4. The shielded cable 30 of this example 2 is a shielded cable 30 for high-speed differential communication used as a transmission line for a high-speed differential communication circuit. The shielded cable 30 is composed of a pair of shielded wires 11, one shielding layer 31, and one sheath 33. Each shielded wire 11 is composed of one insulated wire 12 and one shielding member 15.

[0023] The shielded wire 11 of this embodiment 2 has the same configuration as the shielded wire 11 of embodiment 1. That is, the insulated wire 12 is composed of one conductor 13 and one insulator 14. The shielding member 15 is a cylindrical member that concentrically surrounds the insulated wire 12 (conductor 13 and insulator 14). The shielding member 15 is formed by wrapping a single metal foil around the outer surface of the insulator 14 (insulated wire 12). The outermost layer of the shielded wire 11 is composed of the shielding member 15.

[0024] The shield layer 31 is a cylindrical member made of metal foil. The sheath 33 is an insulating cylindrical member made of synthetic resin. The shield layer 31 is arranged in close contact with the inner circumferential surface of the sheath 33. A pair of shielded wires 11 are twisted together inside the sheath 33 to form a twisted pair wire 32. The shielding member 15 of the shielded wire 11 (twisted pair wire 32) is in contact with the inner circumferential surface of the shield layer 31.

[0025] Within the sheath 33, each shield wire 11 is in contact with the other shield wire 11 and the inner surface of the shield layer 31. Since the pair of shield wires 11 are arranged adjacent to each other in the left-right direction, the semi-cylindrical region of the shielding member 15 that constitutes the outermost layer of each shield wire 11 and faces the other shield wire 11 is positioned to be interposed between the pair of insulated wires 12.

[0026] The shielded cable 30 of this embodiment 2 comprises two unshielded insulated wires 12 arranged in parallel, and a conductive shielding member 15 placed between the two insulated wires 12. With this configuration, even if the insulated wires 12 themselves do not have a shielding function, the conductive shielding member 15 is placed between the two insulated wires 12, so transmission interference between the two insulated wires 12 is suppressed. The two insulated wires 12 are collectively surrounded by the shielding layer 31. With this configuration, not only is transmission interference between the two insulated wires 12 shielded, but noise between the insulated wires 12 and transmission paths other than the insulated wires 12 is also shielded, resulting in excellent shielding performance.

[0027] [Other Embodiments] The present invention is not limited to the embodiments described above in the description and drawings, but is shown in the claims. The present invention includes the meaning of equivalences to the claims and all modifications within the claims, and also includes the following embodiments: - In Embodiments 1 and 2, the shielding member may be arranged in the form of a partition wall between two insulated wires. - In Embodiment 1, the shielding member may consist only of braided wire, or it may be a two-layer form in which metal foil and braided wire are concentrically laminated. - In Embodiment 2, the shield layer may consist only of braided wire, or it may be a two-layer form in which metal foil and braided wire are concentrically laminated.

[0028] 10...Shielded cable 11...Shielded wire 12...Insulated wire 13...Conductor 14...Insulator 15...Shielding material 16...Sheath 20...Comparison cable 21...Twisted pair wire 22...Metal foil 30...Shielded cable 31...Shielding layer 32...Twisted pair wire 33...Sheath La...As value of shielded cable of Example 1 Lb...As value of comparison cable Lc...OABR standard value

Claims

1. A shielded cable used as a transmission path for a high-speed differential communication circuit, comprising two unshielded insulated wires arranged in parallel, and a conductive shielding member positioned between the two insulated wires.

2. The shielding cable for high-speed differential communication according to claim 1, wherein the shielding member individually and around all sides of one of the insulated wires.

3. The shielded cable for high-speed differential communication according to claim 2, wherein the shielding member is composed solely of metal foil.

4. The shielding member is arranged in the form of a partition wall between the two insulated wires, and the two insulated wires are collectively surrounded by the shielding layer, as described in claim 1, for a shielded cable for high-speed differential communication.

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