Signal transmission cable

Abstract

To provide a signal transmission cable capable of restraining a deterioration of transmission characteristics.SOLUTION: A signal transmission cable includes: two aligned insulation core wires; a drain line; and a protective layer disposed on an outer periphery of the insulation core wires and the drain line. Each of the insulation core wires includes: an internal conductor; an insulator disposed on an outer periphery of the internal conductor; and a conductor layer disposed on an outer periphery of the insulator. The conductor layer of at least one of the two insulation core wires is abutting on the drain line. The conductor layer is, for instance, a plating layer. The protective layer includes, for instance, a metal layer on an inner side thereof.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a cable for signal transmission. [Background technology]

[0002] Patent Documents 1 and 2 disclose signal transmission cables. A signal transmission cable 101 shown in Fig. 5 is known in the related art. The signal transmission cable 101 includes two insulated core wires 103A and 103B arranged side by side, a drain wire 111, a metal tape 115, and a jacket 113.

[0003] Each of the two insulated core wires 103A, 103B includes an inner conductor 105 and an insulator 107. The insulator 107 is provided on the outer periphery of the inner conductor 105. The two insulated core wires 103A, 103B and the drain wire 111 are integrated by a metal tape 115. The drain wire 111 is in contact with the metal tape 115. The jacket 113 is provided on the outer periphery of the metal tape 115. The drain wire 111 is connected to the ground at the terminal of the signal transmission cable 101. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-358841 A [Patent Document 2] JP 2010-73463 A Summary of the Invention [Problem to be solved by the invention]

[0005] An air layer 121 exists between the central conductor 105 and the metal tape 115. The air layer 121 is an area occupied by air. If the position of the drain wire 111 is shifted, an imbalance in size of the air layer 121 occurs inside the signal transmission cable 101. If an imbalance in size of the air layer 121 occurs, the transmission characteristics of the signal transmission cable 101 deteriorate.

[0006] In one aspect of the present disclosure, it is preferable to provide a signal transmission cable capable of suppressing deterioration in transmission characteristics. [Means for solving the problem]

[0007] One aspect of the present disclosure includes two insulated core wires arranged side by side, a drain wire, and a protective layer provided on the outer periphery of the two insulated core wires and the drain wire. Each of the two insulated core wires includes an inner conductor, an insulator provided on the outer periphery of the inner conductor, and a conductor layer provided on the outer periphery of the insulator. The conductor layer of at least one of the two insulated core wires is in contact with the drain wire.

[0008] The gap between the internal conductor and the conductor layer is filled with an insulator, making it difficult for an air gap to exist. Therefore, the signal transmission cable according to one aspect of the present disclosure can suppress deterioration of transmission quality caused by an imbalance in the size of the air gap. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view illustrating a configuration of a signal transmission cable according to a first embodiment. [Diagram 2] 6 is a cross-sectional view illustrating a configuration of a signal transmission cable according to a second embodiment. FIG. [Diagram 3] FIG. 11 is a cross-sectional view illustrating a configuration of a signal transmission cable according to a third embodiment. [Figure 4] FIG. 11 is a perspective view illustrating an appearance of a signal transmission cable according to a third embodiment. [Diagram 5] 1 is a cross-sectional view showing a configuration of a conventional signal transmission cable. [Figure 6]1 is a cross-sectional view showing a configuration of a signal transmission cable of a reference example. [Figure 7] 1 is a cross-sectional view showing a configuration of a signal transmission cable of a reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Exemplary embodiments of the present disclosure will now be described with reference to the drawings. First Embodiment 1. Structure of signal transmission cable 1 The configuration of signal transmission cable 1 will be described with reference to Fig. 1. Signal transmission cable 1 is a long linear member. Signal transmission cable 1 has the shape shown in Fig. 1 in any cross section (hereinafter referred to as a transverse cross section) perpendicular to the longitudinal direction of signal transmission cable 1.

[0011] The signal transmission cable 1 includes two insulated core wires 3A, 3B. Each of the two insulated core wires 3A, 3B is a linear member extending straight along the longitudinal direction of the signal transmission cable 1. The two insulated core wires 3A, 3B are arranged side by side. The two insulated core wires 3A, 3B are in contact with each other at their outer circumferential surfaces. The insulated core wire 3A and the insulated core wire 3B have the same configuration. Here, the configuration of the insulated core wire 3A will be described. The insulated core wire 3A includes an inner conductor 5, an insulator 7, and a conductor layer 9.

[0012] The inner conductor 5 is, for example, a linear member made of a metal. Examples of metals include copper, copper alloys, aluminum, and aluminum alloys. The shape of the inner conductor 5 in cross section is, for example, circular, elliptical, and the like. The inner conductor 5 is, for example, a plain wire or a stranded wire. The inner conductor 5 may be a plated wire. The inner conductor 5 transmits, for example, a signal.

[0013] The insulator 7 is provided on the outer periphery of the internal conductor 5. The insulator 7 covers the outer periphery of the internal conductor 5. The cross-sectional shape of the insulator 7 is, for example, circular or elliptical. Examples of the material for the insulator 7 include polyethylene, polypropylene, fluorine-based resin, and polyimide. The material for the insulator 7 is preferably a material with a low dielectric constant. The insulator 7 may be made of one layer or two or more layers.

[0014] The conductor layer 9 is provided on the outer periphery of the insulator 7. The conductor layer 9 covers the outer periphery of the insulator 7. The conductor layer 9 is made of, for example, a metal. Examples of the metal include copper, copper alloy, aluminum, and aluminum alloy. The thickness of the conductor layer 9 is, for example, 1 μm or more and 10 μm or less.

[0015] The conductor layer 9 is, for example, a plating layer. The conductor layer 9 may also be, for example, a sputtered layer, a vapor deposition layer, or the like. The conductor layer 9 may also be, for example, a metal tape attached to the outer circumferential surface of the insulator 7. The conductor layer 9 transmits, for example, a signal.

[0016] The signal transmission cable 1 includes a drain wire 11. The drain wire 11 is a linear member extending straight along the longitudinal direction of the signal transmission cable 1. The drain wire 11 is made of, for example, a metal. Examples of metals include copper, copper alloys, aluminum, and aluminum alloys. The drain wire 11 may be any of a solid wire, a plated wire, and a stranded wire.

[0017] The drain wire 11 is circumscribing both the conductor layer 9 of the insulated core wire 3A and the conductor layer 9 of the insulated core wire 3B. Circumscribing means that the outer peripheral surfaces of the two members are in contact with each other. The drain wire 11 is electrically connected to the conductor layer 9 of the insulated core wire 3A. The drain wire 11 is also electrically connected to the conductor layer 9 of the insulated core wire 3B. In the cross section of the signal transmission cable 1, the direction in which the two insulated core wires 3A and 3B are aligned is defined as the major diameter direction L. The position of the drain wire 11 in the major diameter direction L is the center of the signal transmission cable 1.

[0018] The signal transmission cable 1 includes a protective layer 13. The protective layer 13 is provided on the outer periphery of the two insulated core wires 3A, 3B and the drain wire 11. The protective layer 13 is, for example, a tape member. The tape member may be wound in a spiral manner or vertically. Examples of the material for the protective layer 13 include resins, etc. Examples of resins include polyester and polyimide. The signal transmission cable 1 is, for example, a differential signal transmission cable. When the protective layer 13 is made of a tape member, the following first winding method is more preferable than the second winding method for winding the tape member. Note that up, down, left, and right in the following description refer to up, down, left, and right in FIG. (First winding method) At the start of winding, the tape member passes under the bottom surface of the insulated core wire 3A, then under the bottom surface of the insulated core wire 3B, and then over the right surface of the insulated core wire 3B. Furthermore, the tape member passes over the top surface of the drain wire 111, and then over the top surface of the insulated core wire 3A. In the first winding method, the drain wire 111 can be fixed between the two insulated core wires 3A, 3B in a state in which the two insulated core wires 3A, 3B are fixed so as not to move in the major diameter direction L. By winding the tape member, even if a force acts on the drain wire 111 in a direction that causes the drain wire 111 to get between the two insulated core wires 3A, 3B, the drain wire 111 can be prevented from getting between the two insulated core wires 3A, 3B. As a result, differences in length are unlikely to occur between the insulated core wires 3A, 3B, and the lengths of the insulated core wires 3A, 3B can be kept constant, thereby preventing deterioration of the transmission characteristics. (Second way of rolling) At the start of winding, the tape member passes over the top surface of the insulated core wire 3A, then over the top surface of the drain wire 111, and then over the right surface of the insulated core wire 3B. Furthermore, the tape member passes over the bottom surface of the insulated core wire 3B, and then over the bottom surface of the insulated core wire 3A. In the case of the second winding method, the tape member is started to be wound in a state in which the two insulated core wires 3A, 3B are not fixed so as to not move in the long diameter direction L. Therefore, there is a risk that the drain wire 111 will get between the two insulated core wires 3A, 3B. As a result, a difference in length between the insulated core wires 3A, 3B is likely to occur, making it difficult to keep the lengths of the insulated core wires 3A, 3B constant, and the transmission characteristics are likely to deteriorate.

[0019] 2.Effects of Signal Transmission Cable 1 (1A) The space between the internal conductor 5 and the conductor layer 9 is filled with the insulator 7. Therefore, an air layer is unlikely to exist between the internal conductor 5 and the conductor layer 9. As a result, the signal transmission cable 1 can suppress deterioration of the transmission characteristics caused by an imbalance in the size of the air layer.

[0020] (1B) The conductor layer 9 is, for example, a plating layer. When the conductor layer 9 is a plating layer, the adhesion between the conductor layer 9 and the insulator 7 is high. As a result, it is possible to suppress inter-mode skew. (1C) As a reference example, a signal transmission cable 301 as shown in Fig. 6 and Fig. 7 is assumed. The signal transmission cable 301 includes two insulated core wires 303A and 303B. Each of the insulated core wires 303A and 303B includes an inner conductor 305 and an insulator 307. The signal transmission cable 301 includes a metal tape 309 wound collectively around the two insulated core wires 303A and 303B.

[0021] The signal transmission cable 301 includes a drain wire 311. In the embodiment shown in Fig. 6, there is one drain wire 311. In the embodiment shown in Fig. 7, there are two drain wires 311. The drain wire 311 is provided on the outer periphery of the metal tape 309. The signal transmission cable 301 includes a jacket 313. The jacket 313 is provided on the outer periphery of the metal tape 309 and the drain wire 311.

[0022] The signal transmission cable 301 has a large outer diameter because the drain wire 311 is provided on the outer periphery of the metal tape 309. In addition, it is difficult to bend the signal transmission cable 301 so that the drain wire 311 is on the inside or outside. The outer diameter of the signal transmission cable 1 can be reduced compared to the signal transmission cable 301. Furthermore, the signal transmission cable 1 is easier to bend in any direction compared to the signal transmission cable 301.

[0023] (1D) Drain wire 11 is in contact with conductor layer 9 of insulated core wire 3A and conductor layer 9 of insulated core wire 3B, respectively. Therefore, drain wire 11 has good grounding properties. <Second embodiment> 1. Differences from the first embodiment The second embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0024] In the first embodiment described above, the entire protective layer 13 is made of resin. In contrast, in the second embodiment, as shown in FIG. 2, the protective layer 13 is made of two layers, an inner layer 13A and an outer layer 13B. The inner layer 13A is a layer on the inner periphery side of the protective layer 13. The inner layer 13A is a metal layer. Thus, the protective layer 13 has a metal layer on the inner periphery side. Examples of metals constituting the inner layer 13A include copper, copper alloys, aluminum, and aluminum alloys. The outer layer 13B is a layer made of resin. Examples of resins constituting the outer layer 13B include polyester and polyimide.

[0025] In the first embodiment described above, the drain wire 11 is circumscribing the conductor layer 9 of the insulated core wire 3A and the conductor layer 9 of the insulated core wire 3B. In contrast, in the second embodiment, as shown in FIG. 2, the drain wire 11 is circumscribing the conductor layer 9 of the insulated core wire 3A but is not circumscribing the conductor layer 9 of the insulated core wire 3B. In the second embodiment, the drain wire 11 is in contact with the inner layer 13A. The drain wire 11 and the inner layer 13A are electrically connected. In the second embodiment, the position of the drain wire 11 in the major diameter direction L is shifted toward the insulated core wire 3A from the center of the signal transmission cable 1.

[0026] 2.Effects of Signal Transmission Cable 1 According to the second embodiment described above in detail, in addition to the effects (1A) to (1C) of the first embodiment described above, the following effect is also obtained.

[0027] (2A) The drain wire 11 is in contact with the conductor layer 9 and the inner layer 13A of the insulated core wire 3A, respectively. Therefore, the drain wire 11 has good grounding properties. <Third embodiment> 1. Differences from the first embodiment The third embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

[0028] In the first embodiment described above, the protective layer 13 is made of a single tape member. In contrast, in the third embodiment, as shown in Fig. 3, the protective layer 13 has a configuration in which an inner circumferential side tape 14A and an outer circumferential side tape 14B are wound in an overlapping manner. The outer circumferential side tape 14B is located on the outer circumferential side of the inner circumferential side tape 14A.

[0029] The inner tape 14A has a two-layer structure consisting of a layer made of metal and a layer made of resin. The metal constituting the metal layer is not particularly limited, and examples thereof include copper, copper alloy, aluminum, aluminum alloy, iron, etc. The inner tape 14A is wound so that the layer made of metal is on the inner circumferential side.

[0030] The layer made of metal contacts the conductor layer 9 of the insulated core wire 3A, the conductor layer 9 of the insulated core wire 3B, and the drain wire 11. Examples of resins that form the resin layer in the inner circumferential tape 14A include polyester and polyimide.

[0031] The outer peripheral tape 14B is made of resin. Examples of resin include polyester and polyimide. The outer peripheral tape 14B is made of, for example, two or more layers. Each layer in the two or more layers is made of, for example, a different resin. The outer peripheral tape 14B includes, for example, an acrylic layer and a polyester layer.

[0032] For example, the outer circumferential tape 14B is wound in a spiral shape as shown in Fig. 4. The inner circumferential tape 14A may be wound in a spiral shape or vertically. In the first embodiment described above, the insulator 7 consists of one layer. In contrast, in the third embodiment, as shown in FIG. 3, the insulator 7 consists of two layers, an inner layer 7A and an outer layer 7B. For example, the inner layer 7A and the outer layer 7B are made of different resins. For example, the inner layer 7A is made of FEP or polypropylene. FEP is a fluororesin. For example, the outer layer 7B is made of polyethylene. Also, in the third embodiment, as shown in FIG. 3, the conductor 5 consists of a compressed stranded conductor obtained by compressing a stranded conductor into a circular shape.

[0033] 2.Effects of Signal Transmission Cable 1 According to the third embodiment described above in detail, in addition to the effects (1A) to (1C) of the first embodiment described above, the following effect is also obtained.

[0034] (3A) The drain wire 11 is in contact with and electrically connected to the metal layer of the inner tape 14A and the conductor layer 9 of the insulated core wire 3A, respectively, so that the drain wire 11 has good grounding properties. <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0035] (1) The function of one component in each of the above embodiments may be shared by multiple components, or the functions of multiple components may be performed by one component. Also, part of the configuration of each of the above embodiments may be omitted. Also, at least part of the configuration of each of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0036] For example, in the first embodiment, the conductor layer 9 of one of the two insulated core wires 3A, 3B does not have to be in contact with the drain wire 11. In the first embodiment, the protective layer 13 may have a metal layer on the inner periphery side. The metal layer contacts the drain line 11, for example, and is electrically connected to the drain line 11.

[0037] In the second embodiment, the conductor layers 9 of both of the two insulated core wires 3A, 3B may be in contact with the drain wire 11 and electrically connected thereto. (2) In addition to the above-described signal transmission cable 1, the present disclosure can be realized in various forms, such as a system including the signal transmission cable 1 as a component, a method for manufacturing the signal transmission cable 1, and the like. [Explanation of symbols]

[0038] 1...signal transmission cable, 3A, 3B...insulated core wire, 5...inner conductor, 7...insulator, 7A...inner layer, 7B...outer layer, 9...conductor layer, 11...drain wire, 13...protective layer, 13A...inner layer, 13B...outer layer, 14A...inner circumferential tape, 14B...outer circumferential tape, 121...air layer, 301...signal transmission cable, 303A, 303B...insulated core wire, 309...metal tape, 311...drain wire, 313...jacket

Claims

1. Two insulated core wires arranged side by side; Drain wire, a protective layer provided around the two insulated core wires and the drain wire; Equipped with The two insulated core wires each have An inner conductor; an insulator provided on an outer periphery of the internal conductor; A conductor layer provided on the outer periphery of the insulator; Equipped with The conductor layer of at least one of the two insulated core wires is in contact with the drain wire. Signal transmission cable.

2. 2. The signal transmission cable according to claim 1, The conductor layer is a plating layer. Signal transmission cable.

3. 3. The signal transmission cable according to claim 1, The protective layer has a metal layer on the inner circumferential side. Signal transmission cable.

Images