Shielded cable for high-speed differential communication

Abstract

Suppress transmission interference. [Solution] The shielded cable 10 for high-speed differential communication is a shielded cable 10 used as a transmission path for a high-speed differential communication circuit, and comprises two unshielded insulated wires 12 arranged in parallel, and a conductive shielding member 15 placed between the two insulated wires 12. The insulated wires 12 themselves do not have a shielding function, but because the conductive shielding member 15 is placed between the two insulated wires 12, transmission interference between the two insulated wires 12 is suppressed.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a communication shielded cable including a pair of core wires in which twisted conductors are covered with an insulator, and a shield layer that collectively surrounds the pair of core wires.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[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 transmission failures may occur due to crosstalk or the like in the pair of core wires.

[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.

Means for Solving the Problems

[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, including two non-shielded type coated electric wires arranged in parallel, and a conductive shielding member disposed between the two coated electric wires.

Effects of the Invention

[0007] According to this disclosure, transmission failures can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a front view of the shielded cable of Example 1. [Figure 2] Figure 2 is a front view of the comparison cable. [Figure 3] Figure 3 is a graph showing the shielding performance of the shielded cable in Example 1 and a comparison cable. [Figure 4] Figure 2 is a front view of the shielded cable of Example 2. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] First, embodiments of this disclosure will be listed and described. Any combination of the following embodiments, insofar as they do not contradict each other, is also included as a form for carrying out the invention. The shielded cable for high-speed differential communication described herein 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 placed between the two insulated wires. With this configuration, even if the insulated wires themselves do not have a shielding function, the placement of a conductive shielding member between the two insulated wires suppresses transmission interference between the two insulated wires.

[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)(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 two insulated wires are enclosed together by a shielding layer. With this configuration, not only transmission interference between the two insulated wires but also noise between the insulated wires and transmission lines other than the insulated wires can be shielded, thus providing excellent shielding performance.

[0013] [Details of the embodiments of this disclosure] [Example 1] A shielded cable 10 of Embodiment 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 scope equivalent to the claims are included. In Embodiment 1, the vertical direction and height direction are used synonymously. The left-right direction and 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 path in 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 covered wire 12 is composed of one conductor 13 and one insulator 14. The conductor 13 is, for example, made of a conductive stranded wire. The insulator 14 is made of a material having electrical insulation properties such as synthetic resin. The insulator 14 concentrically surrounds the conductor 13 over the entire circumference. The shielding member 15 is a cylindrical member that concentrically surrounds the covered wire 12 (conductor 13 and insulator 14). The shielding member 15 is formed by winding a single metal foil around the outer peripheral surface of the insulator 14 (covered wire 12). The outermost layer of the shielded wire 11 is constituted by the shielding member 15.

[0016] The sheath 16 is an insulating cylindrical member made of synthetic resin. The outer peripheral shape of the sheath 16 is a perfect circle. The inner peripheral shape of the sheath 16 is an ellipse with the major axis oriented in the left - right direction. The pair of shielded wires 11 are arranged side - by - side adjacent to each other in the left - right direction within the sheath 16. Within the sheath 16, each shielded wire 11 is in contact with the inner peripheral surface of the sheath 16 and the shielded wire 11 on the opposite side. Since the pair of shielded wires 11 are arranged side - by - side 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 shielded wire 11 and faces the shielded wire 11 on the opposite side is arranged to be interposed between the pair of covered wires 12.

[0017] The pair of shielded wires 11 are regarded as a pair of Dual - Coax wires and are used as a transmission line for high - speed differential communication. FIG. 2 shows a comparison target cable 20 for comparing with the shielded cable 10 of the first embodiment regarding shielding performance. The comparison target cable 20 is a cable obtained by removing the sheath and the braided wire from a Shielded Twisted Pair Cable (STP cable) having a two - layer shield layer composed of a metal foil and a braided wire. That is, the comparison target cable 20 is a cable in which one twisted pair wire 21 is surrounded by a metal foil 22. The twisted pair wire 21 is constituted by spirally bringing together two non - shielded type covered wires 12 in which the conductor 13 is surrounded by the insulator 14.

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

[0019] As shown in the graph, the As value Lb of the comparison target cable 20 in which the braided wire is removed and the two conductors 13 are collectively surrounded by the metal foil 22 has deteriorated significantly and does not satisfy the OABR standard value Lc. On the other hand, the As value La of the shielded cable 10 of the first embodiment in which the conductors 13 of each shielded electric wire 11 are individually covered by the conductive shielding member 15 clears the OABR standard value Lc and exhibits shielding performance superior to that of the comparison target cable 20.

[0020] The shielded cable 10 for high-speed differential communication of the first embodiment includes two non-shielded type coated electric wires 12 arranged in parallel and a conductive shielding member 15 disposed between the two coated electric wires 12. According to this configuration, even if the coated electric wire 12 itself does not have a shielding function, since the conductive shielding member 15 is disposed between the two coated electric wires 12, the transmission failure between the two coated electric wires 12 is suppressed.

[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] A shielded cable 30 of Embodiment 2, which embodies the present disclosure, will be described with reference to Figure 4. The shielded cable 30 of Embodiment 2 is a shielded cable 30 for high-speed differential communication used as a transmission line in 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 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 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 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 transmission interference between the two insulated wires 12 but also noise between the insulated wires 12 and transmission paths other than the insulated wires 12 can be shielded, thus providing excellent shielding performance.

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

[0028] 10…Shielded cable 11...Shielded power lines 12...Insulated wire 13... Conductor 14…Insulator 15... Shielding member 16... Sheath 20…Comparison Cable 21...Twisted pair wire 22… Metal foil 30…Shielded cable 31...Shield layer 32...Twisted pair wire 33...Sheath La...As value of the shielded cable in Example 1 Lb…As value of the comparison cable

Claims

1. A shielded cable used as a transmission line for high-speed differential communication circuits, Two unshielded insulated wires are routed in parallel, A shielded cable for high-speed differential communication comprising a conductive shielding member positioned between the two insulated wires.

2. The shielded cable for high-speed differential communication according to claim 1, wherein the shielding member individually and all around surrounds one of the insulated electric 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 electric wires. The shielded cable for high-speed differential communication according to claim 1, wherein the two insulated wires are collectively surrounded by a shielding layer.

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