Communication cable

Abstract

To reduce influence of deterioration of communication characteristics due to variation of a separation distance between pairs of a twisted wire conductor and a shield layer.SOLUTION: Provided is a communication cable that is preferably used for communication in an automobile, including: a twisted pair wire in which a pair of core wires having a twisted wire conductor in which a plurality of element wires are twisted together and an insulator covering the twisted wire conductor are twisted together; and a sheath covering the twisted pair wire; wherein a ratio Lc / Ls of a core wire pitch Lc along an axial direction of a rotation axis of twisting in the core wire to an element wire pitch Ls along the core wire in the element wire is 2 or less. The twisted wire conductor is an uncompressed twisted wire conductor or a compressed twisted wire conductor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a communication cable. [Background technology]

[0002] In recent years, there has been an increasing demand for high-speed communications in the automotive field. In high-speed communications, communication cables capable of transmitting differential signals are used as a noise countermeasure (see, for example, Patent Documents 1 and 2).

[0003] Patent Document 1 describes a communication cable including a twisted pair wire, a first sheath that covers the twisted pair wire, a shielding layer that covers the first sheath, and a second sheath that covers the shielding layer. The twisted pair wire described in Patent Document 1 has a configuration in which a pair of core wires are twisted together, each core wire having a stranded conductor formed by twisting together multiple element wires and an insulator that covers the stranded conductor.

[0004] Patent Document 2 describes a bend-resistant cable having a braided shield layer provided around the outer periphery of a cable core, in which the twist direction of first shield wires in one direction that make up the braided shield layer is the same as the collective twist direction of core wires that make up the outermost layer of the cable core, the braid pitch of the first shield wires in the longitudinal direction of the bend-resistant cable is the same as or close to the collective twist pitch of the core wires, and the second shield wires in the other direction that make up the braided shield layer that intersects with the twist direction of the core wires are made of wires with excellent bend resistance.

[0005] Also, a known type of communication cable is a JUTP (Jacket Unshielded Twisted Pair) cable, which includes a twisted pair wire formed by twisting together a pair of core wires, each of which has a conductor and an insulator covering the conductor, and a sheath that covers the entire cable (see Patent Document 3). JUTP cables are required to have low loss, little mode conversion loss, and excellent mechanical properties such as flexibility and vibration resistance.

[0006] To reduce mode conversion loss and improve mode conversion, the signal must be electrically symmetrical when viewed from the single end, and the amplitude and phase of the single-mode signal must be consistent between the differential pair. To achieve this, the distance between the ground and the stranded conductor must be the same between the strand pairs. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6760392 [Patent Document 2] Utility Model Registration No. 2599592 [Patent Document 3] Patent Publication No. 2021-136105 Summary of the Invention [Problem to be solved by the invention]

[0008] The above-mentioned prior art discloses specifying the hardness of the coating material to stabilize the relative position of the conductors during the manufacturing process. However, twisted wires are typically used for the conductors. Therefore, the cross-sectional shape perpendicular to the longitudinal direction of the twisted conductors is not perfectly circular. Even if the relative position of the twisted conductors is stabilized by specifying the hardness of the coating material, the cross-sectional shape varies along the longitudinal direction depending on the twist pitch of the twisted conductors and the twist pitch of the core wire. As a result, the mode conversion loss is affected by the variation in the cross-sectional shape of the twisted conductor along the longitudinal direction. Therefore, a technology that can mitigate the deterioration of communication characteristics due to the variation in the cross-sectional shape of the twisted conductor and improve the mode conversion characteristics is desired.

[0009] The present invention has been made in view of the above, and an object of the present invention is to provide a communication cable that can improve mode conversion characteristics. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems and achieve the object, a communication cable according to one embodiment of the present invention comprises a twisted pair wire in which a pair of core wires are twisted together, each core wire having a stranded conductor in which a plurality of strands are twisted together and an insulator covering the stranded conductor, and a sheath covering the twisted pair wire, wherein the ratio Lc / Ls of the core wire pitch Lc along the axial direction of the twisting of the core wire to the strand pitch Ls along the core wire in the strands is 2 or less.

[0011] A communication cable according to one aspect of the present invention is characterized in that, in the above invention, the stranded conductor is a non-compressed stranded conductor.

[0012] In the communication cable according to one aspect of the present invention, in the above invention, the stranded conductor is a compressed stranded conductor.

[0013] A communication cable according to one aspect of the present invention is characterized in that, in the above invention, the communication cable is used for communication in an automobile. [Effects of the Invention]

[0014] According to the communication cable of the present invention, it is possible to improve the mode conversion characteristics. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing the configuration of a communication cable according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of the communication cable shown in FIG. [Figure 3] FIG. 3 is a diagram for explaining the core wire pitch and the wire pitch. [Figure 4] FIG. 4 is a graph showing the results of a simulation of a communication cable according to an embodiment of the present invention. [Figure 5]FIG. 5 is a graph showing the results of a simulation of a communication cable according to an embodiment of the present invention. [Figure 6] FIG. 6 is a graph showing the results of a simulation of a communication cable according to an embodiment of the present invention. [Figure 7] FIG. 7 is a graph showing the results of a simulation of a communication cable according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings of the embodiment below, the same or corresponding parts are designated by the same reference numerals. Furthermore, the present invention is not limited to the embodiment described below. Furthermore, the drawings are schematic, and the dimensional relationships and ratios of each element may differ from the actual ones. Furthermore, the drawings may include parts whose dimensional relationships and ratios differ from each other.

[0017] (Communication cable) Fig. 1 is a diagram showing the configuration of a communication cable 1 according to one embodiment. Fig. 2 is a cross-sectional view of the communication cable 1 shown in Fig. 1 taken along line II-II. The communication cable 1 is installed in, for example, an automobile and used for communication in accordance with the Ethernet (registered trademark) standard in the automobile in which it is installed. As shown in Figs. 1 and 2, the communication cable 1 according to this embodiment includes twisted pair wires 2 and a sheath 3, but is not provided with a shield or shield layer.

[0018] The twisted pair wire 2 is formed by twisting together a pair of core wires 2A and 2B. The pair of core wires 2A and 2B have the same configuration. In the following explanation, the configuration of the core wire 2A will be described, but the same applies to the core wire 2B.

[0019] The core wire 2A includes a stranded conductor 21 and an insulator 22. As shown in Fig. 2, the stranded conductor 21 is formed by twisting together a plurality of element wires 211. The stranded conductor 21 is covered with the insulator 22.

[0020] The wires 211 may be made of copper (Cu), copper alloys (Cu alloys), aluminum (Al), aluminum alloys (Al alloys), or the like. Here, the stranded conductor 21 may be a compressed stranded conductor in which a plurality of wires 211 are compressed, or a non-compressed stranded conductor in which a plurality of wires 211 are not compressed. Although the number of wires 211 is seven in Fig. 2, it is not limited to this number and may be any other number.

[0021] The material of the insulator 22 may be a polyolefin resin or a vinyl chloride resin-based resin, such as polyethylene (PE), ethylene vinyl acetate (EVA), or polypropylene (PP).

[0022] The sheath 3 covers the twisted pair wires 2. In this embodiment, a gap 31 is formed between the twisted pair wires 2 and the inner surface of the sheath 3. Here, the sheath 3 can be made of a polyolefin resin such as PE (polyethylene), EVA (ethylene vinyl acetate), or PP (polypropylene), or a resin based on vinyl chloride resin.

[0023] (Simulation results for communication cables) Next, evaluation was performed by simulation using the following model of the communication cable 1 configured as above. The configuration of the model used in the simulation was the same as that of the communication cable 1 described above. Here, the sheath 3 had a diameter of 2.6 mm, a thickness of 0.34 mm, and a dielectric constant of 2.25. The wires 211 had a diameter of 0.16 mm. Furthermore, the stranded conductor 21 had a diameter of 0.48 mm and a conductivity of 53% IACS. The insulator 22 had a diameter of 0.95 mm and a dielectric constant of 2.25.

[0024] Fig. 3 is a diagram illustrating the core wire pitch Lc and the wire pitch Ls. Specifically, Fig. 3 is a diagram illustrating the core wires 2A and 2B viewed from a direction perpendicular to the longitudinal direction of the above-described communication cable 1. For ease of explanation, Fig. 3 illustrates the insulator 22 of one of the core wires 2B by removing it.

[0025] 3, the core wire pitch Lc is the length of one twist of the core wires 2A and 2B, and this length means the length along the axial direction of the twisting of the core wires 2A and 2B (the left-right direction in FIG. 3). On the other hand, the wire pitch Ls is the length of one twist of the wires 211, and this length means the length along the core wires 2A and 2B (core wire 2B in the example of FIG. 3).

[0026] In the above-described model, the distance to the ground is 10 mm, and the core wire pitch Lc shown in Figure 3 is set to various values ​​within the range of 9 mm to 50 mm, such as 9 mm, 10 mm, 11 mm, 11.5 mm, 14 mm, 23 mm, 30 mm, 37 mm, and 50 mm. Furthermore, in the above-described model, the strand pitch Ls shown in Figure 3 is set to various values ​​within the range of 2 mm to 37 mm, such as 2 mm, 3 mm, 6 mm, 9 mm, 13 mm, 19 mm, 23 mm, 30 mm, and 37 mm. Through simulations using the above core wire pitches Lc and strand pitches Ls, the mode conversion characteristics of transmission mode conversion (Sdc21) and reflection mode conversion (Sdc22) were derived.

[0027] 4, 5, 6, and 7 are graphs showing simulation results. Specifically, FIGS. 4 and 5 are graphs showing simulation results when the stranded conductor 21 is a "non-compressed stranded conductor." Meanwhile, FIGS. 6 and 7 are graphs showing simulation results when the stranded conductor 21 is a "compressed stranded conductor." In FIGS. 4 and 6, the horizontal axis represents Lc / Ls, and the vertical axis represents the amplitude value of the transmission mode conversion (Sdc21) extracted at 0.4 GHz. In FIGS. 5 and 7, the horizontal axis represents Lc / Ls, and the vertical axis represents the amplitude value of the reflection mode conversion (Sdc22) extracted at 0.4 GHz. Note that 0.4 GHz is a frequency conforming to the Ethernet (registered trademark) standard for automobiles in which the communication cable 1 is installed.

[0028] For example, in Figures 4 to 7, point P1 is a plot of the amplitude values ​​of the transmission mode characteristics (Sdc21) and reflection mode characteristics (Sdc22) extracted at 0.4 GHz when the core wire pitch Lc is 45 mm, the wire pitch Ls is 22.5 mm, and Lc / Ls = 2.

[0029] 4 to 7, the simulation results showed that in both cases where the stranded conductor 21 was an "uncompressed stranded conductor" and a "compressed stranded conductor," when Lc / Ls exceeded 2, the amplitude values ​​of the transmission mode characteristics (Sdc21) and the reflection mode characteristics (Sdc22) increased and the variation in these amplitude values ​​also increased, resulting in poor mode conversion characteristics.On the other hand, when Lc / Ls was 2 or less, the amplitude values ​​of the transmission mode characteristics (Sdc21) and the reflection mode characteristics (Sdc22) decreased and the variation in these amplitude values ​​also decreased, resulting in good mode conversion characteristics.

[0030] Based on the above simulation results, in the communication cable 1, it is preferable that Lc / Ls is greater than 0 and less than or equal to 2 (0 < Lc / Ls ≦ 2). According to the findings of the present inventor, the value of Lc / Ls is preferably about 1.3, preferably 1.0 or more and 1.7 or less (1.0 ≦ Lc / Ls ≦ 1.7), and more preferably 1.2 or more and 1.5 or less (1.2 ≦ Lc / Ls ≦ 1.5).

[0031] As described above, according to the communication cable 1 according to the present embodiment, by setting Lc / Ls to be greater than 0 and less than or equal to 2, as can be seen from the simulation results, the mode conversion characteristics can be made good.

[0032] By the way, when Lc / Ls is greater than 2, as can be seen from the simulation results, there are some with good mode conversion characteristics. However, the variation in the amplitude values of the transmission mode characteristics (Sdc21) and the reflection mode characteristics (Sdc22) is large. When the variation in the amplitude values is large like this, it is necessary to determine whether the mode conversion characteristics are good or not by inspection, and the manufacturing cost of the communication cable 1 becomes high. On the contrary, when Lc / Ls is less than or equal to 2, as can be seen from the simulation results, the variation in the amplitude values of the transmission mode characteristics (Sdc21) and the reflection mode characteristics (Sdc22) is small. Therefore, the inspection for whether the mode conversion characteristics are good or not can be reduced, and the manufacturing cost of the communication cable 1 can be reduced.

[0033] Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical concept of the present invention are possible. Configurations that appropriately combine the above-described components are also included in the present invention. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiment, and various modifications are possible. For example, the numerical values ​​and materials listed in the above-described embodiment are merely examples, and different numerical values ​​and materials may be used as necessary. The present invention is not limited by the description and drawings that form a part of the disclosure of the present invention according to this embodiment.

[0034] (Other embodiments) Although the embodiments of the present invention have been described above, the present invention should not be limited to the above-described embodiments. In the communication cable 1 according to this embodiment, the sheath 3 is configured as a pipe type, but it is also possible to configure the sheath 3 as a solid type and adopt a configuration in which no gap is provided between the twisted pair wires 2 and the inner surface of the sheath 3.

[0035] Although the communication cable 1 according to this embodiment is installed in an automobile, the present invention is not limited to this and may be installed in other electronic devices. [Explanation of symbols]

[0036] 1. Communication cable 2 twisted pair wire 2A, 2B core wire 3 Sheath 21 Stranded conductor 22 Insulators 211 Wire Lc core wire pitch Ls wire pitch P1 point

Claims

1. a twisted pair wire in which a pair of core wires are twisted together, each core wire having a stranded conductor formed by twisting together a plurality of wires and an insulator covering the stranded conductor; a sheath that covers the twisted pair wires, The ratio Lc / Ls of the core wire pitch Lc along the axial direction of the twisting of the core wire to the wire pitch Ls along the core wire in the wire is: 2 or less A communication cable characterized by:

2. The stranded conductor is It is a non-compressed stranded conductor.

2. The communication cable according to claim 1.

3. The stranded conductor is Compressed stranded conductor 2. The communication cable according to claim 1.

4. The communication cable comprises: Used for communication in automobiles 2. The communication cable according to claim 1.

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