JP2009093908A - Communication cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication cable suitable for signal transmission in a high-frequency band of a gigabit rate. <P>SOLUTION: The communication cable is provided with an interposition (1) having four housing areas (1a-1d) to house one set of twisted pair wires, four sets of twisted pair wires (2a-2d), which are respectively arranged in the respective housing areas of the interposition and whose twisting pitches are different from each other, a linear spacer (3) spirally wound around the outer periphery of an assembly of the interposition and the four sets of twisted pair wires, and a sheath (4) to cover the spacer and the assembly of the twisted pair wires. The spiral spacer regulates a distance between the assembly of the twisted pair wires and the sheath, thereby forming an air layer (5) between the outer peripheral face of the assembly of the twisted pair wires and the sheath. Since a dielectric constant of air is very small, even if many communication cables are stacked, three air layers are formed between the assemblies of the twisted pair wires of the cables adjacent to each other. As a result, even if signal transmission is performed in a high-frequency band, electrostatic coupling is suppressed, thereby significantly improving alien crosstalk. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication cable suitable for signal transmission at a 10 gigabit level, and more particularly to a communication cable in which crosstalk between cables (alien crosstalk) is greatly improved.

  With the development of LAN, there is a strong demand for the development of communication cables for signal transmission suitable for high-speed communication. As the transmission rate becomes higher, it is necessary to improve the crosstalk attenuation characteristic of the communication cable, and a communication cable using a cruciform interposition is known as a communication cable with improved crosstalk attenuation characteristics (for example, Patent Documents). 1). In this known communication cable, twisted pair wires having different twist pitches are respectively arranged in four storage areas whose cross sections are defined by a cross-shaped interposition, thereby improving crosstalk attenuation characteristics between adjacent twisted wires. It has been.

Japanese Patent Laid-Open No. 11-53958

  The communication cable using the cross-shaped interposition has improved the crosstalk attenuation characteristics between the twisted pair wires arranged in the cable, and thus the characteristics satisfying the standard value specified in Category 6 have been obtained. However, in the current communication system, there is a strong demand for the development of a communication cable used in a high frequency band of about 100 Mbps to 10 Gbps, and there is a limit to the improvement of the crosstalk attenuation amount in the communication cable using the cross shape. It was. In other words, when using a high-frequency band of the gigabit rate or higher, not only the crosstalk attenuation between twisted pair wires in the communication cable but also the interference (crosstalk) between the communication cables becomes prominent, and alien crosstalk needs to be improved. .

  In many local information wiring systems (LANs), external networks such as the Internet are connected to equipment such as floor switches and switching hubs via optical communication cables, and floor switches are connected to horizontal cables via equipment cables. The horizontal cable is connected to outlets distributed on the floor. The horizontal cable functions as a trunk line on each floor, and many wirings are stacked and densely arranged. For this reason, alien crosstalk, which is crosstalk between cables, easily occurs in horizontal cables, and the occurrence of alien crosstalk is particularly noticeable in a high frequency band. When alien crosstalk occurs noticeably, the communication quality is drastically reduced, so improvement of alien crosstalk is an urgent issue.

An object of the present invention is to realize a communication cable in which alien crosstalk is greatly improved in a communication cable used in a high frequency band of a gigabit rate or higher.
Another object of the present invention is to provide a communication cable suitable as a horizontal cable in a LAN.

A communication cable according to the present invention is a communication cable suitable for signal transmission in a high-frequency band, and has four storage areas for storing twisted pair wires, and has a substantially cross-shaped interposition, and each of the interposition storage areas. Each of the four twisted pair wires having different twist pitches, and a linear spacer spirally wound around the outer periphery of the assembly of the interposition and the four twisted pair wires at a predetermined pitch A sheath covering the outer periphery of the assembly of twisted pair wires around which the linear spacer is wound,
An air layer is formed between the outer peripheral surface of the assembly of twisted pair wires and the sheath, except for a portion where a line-shaped spacer is located, over substantially the entire circumference.

  As a result of various experiments and analyzes on the crosstalk attenuation characteristics of communication cables used in the high frequency band of the gigabit rate or higher by the present inventors, it has been found that electrostatic coupling generated between the cables is strongly acting. For example, in a data center or the like, a large number of horizontal cables are stacked and densely arranged, so that electrostatic coupling occurs between adjacent cables and alien crosstalk occurs. In order to prevent electrostatic coupling, it is assumed that the distance between adjacent cables is increased. In this case, it is conceivable to increase the thickness of the sheath that is the outer jacket of the communication cable. However, since the sheath material has a relatively large dielectric constant, Enrian crosstalk cannot be improved by simply increasing the thickness of the sheath. Therefore, as a result of further experiments by the present inventors, it has been found that it is extremely effective to form an air layer between the assembly of twisted pair wires and the sheath. That is, since the dielectric constant of air is much smaller than the dielectric constant of the sheath material, if an air layer is formed between the assembly of twisted pair wires and the sheath, a large number of cables are stacked and the sheaths of adjacent cables are Even if they come into contact with each other, an air layer having a low dielectric constant is interposed between a pair of twisted wires of adjacent cables, so that it is possible to effectively prevent the occurrence of electrostatic coupling.

  As a result of further experiments by the present inventor, as a method of forming an air layer between the assembly of twisted pair wires and the sheath, a linear spacer is spirally formed on the outer periphery of the assembly of crossed wires and twisted pair wires. An air layer is formed between the sheath and the twisted wire assembly over almost the entire circumference of the cable by covering the outer periphery of the twisted wire assembly around which the spacer is wound with the sheath. Can do. At this time, an air layer is not formed in a portion where the linear spacer exists, but since the proportion of the linear spacer is extremely small, an air layer is formed over almost the entire circumference of the cable. Since the dielectric constant of air is much smaller than the dielectric constant of the dielectric material used as the sheath member of the communication cable, electrostatic coupling between adjacent communication cables is suppressed, and alien crosstalk is greatly improved. Furthermore, when a plurality of communication cables are stacked, the line-shaped spacer also functions as a spacer that regulates the adjacent distance between adjacent communication cables, so an air layer is also formed between the sheaths of adjacent communication cables. Thus, the effect of further improving alien crosstalk is achieved.

  A preferred embodiment of the communication cable according to the present invention is characterized in that the linear spacer is made of a columnar or hollow cylindrical dielectric material. Here, the hollow cylindrical spacer is more effective in improving the alien crosstalk because the dielectric constant of the spacer itself becomes smaller.

  Another preferred embodiment of the communication cable according to the present invention is an aggregate of polyethylene, polypropylene, polyvinyl chloride or cellulose fibers having a conductor size of AWG23 and having a diameter of 1.6 to 2.0 mm as a linear spacer. A linear spacer is used, and the linear spacer is spirally wound around the outer periphery of a twisted pair assembly at a twist pitch of 20 to 40 mm.

A multi-pair communication cable according to the present invention is a multi-pair communication cable having an aggregate of a plurality of communication cables and a sheath member covering an outer periphery of the aggregate of the communication cables.
The plurality of communication cables have four storage areas for storing twisted pair wires, and are disposed in each of the intervening storage areas having a substantially cruciform cross section and having different twist pitches. A pair of wire, a line-shaped spacer spirally wound around the outer periphery of the aggregate of the interposition and the four twisted-pair wires at a predetermined pitch, and a twisted pair wire on which the line-shaped spacer is wound A sheath covering the outer periphery of the assembly, and an air layer is formed over substantially the entire periphery except for the portion where the line spacer is located between the outer peripheral surface of the assembly of the twisted pair wires and the sheath. It is characterized by being.

  Since the communication cable according to the present invention has an air layer between the assembly of twisted pair wires and the sheath, even when configured as a multi-pair communication cable in which a large number of communication cables are assembled, Since an air layer is present on the outer periphery of each twisted pair assembly, interference between cables is suppressed, and a multi-pair communication cable with improved alien crosstalk is realized.

  In the present invention, since an air layer exists between the assembly of the twisted pair wires and the sheath over almost the entire circumference, even if a large number of communication cables are stacked and arranged, the air is interposed between the twisted wires of adjacent cables. Since the layer is formed, the problem of electrostatic coupling is prevented and alien crosstalk is greatly improved. As a result, a communication cable useful for signal transmission of 10 gigabit rate or higher is realized.

  FIG. 1 shows an example of a communication cable according to the present invention. FIG. 1A is a cross-sectional view taken along a plane orthogonal to the central axis of the cable, and FIG. 1B includes the central axis of the cable. FIG. 1C is a schematic cross-sectional view showing a state in which two communication cables are stacked. In the center of the cable, an interposition 1 having a cross-shaped cross section is arranged. The interposition 1 has four storage areas 1a to 1d, and twisted pair wires 2a to 2d having different twist pitches are arranged in the storage areas 1a to 1d, respectively. As an example, the twist pitches of the twisted pair wires 2a to 2d are set to 6 mm, 7 mm, 8 mm, and 9 mm, respectively. The interposition 1 and the four twisted pair wires 2a to 2d are twisted at a predetermined pitch, and a linear spacer 3 is wound around the outer periphery of the assembly spirally at a predetermined pitch. A sheath 4 covers the outer periphery of the twisted pair assembly around which the spacer 3 is wound.

  The line-shaped spacer 3 functions as a spacer member that forms an air layer between the assembly of twisted-pair wires including the interposition and the sheath 4. The spacer 3 is composed of a columnar (solid type) or hollow cylindrical flexible linear body, such as polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), or an aggregate of cellulose fibers. It is made of a dielectric material. The diameter of the line spacer is set to 1.6 to 2.0 mm, and the pitch for spiral winding is set to 20 to 40 mm.

  The line-shaped spacer 3 can be formed of, for example, a polyethylene string having a diameter of 1.6 to 2.0 mm and a circular cross section. Since this polyethylene string has appropriate hardness and flexibility, it can be wound spirally at a predetermined pitch while running an assembly of twisted wires using an existing winding machine. If a polyethylene string is wound around the outer periphery of the assembly of twisted wire pairs and then covered with a sheath, as shown in FIG. 1B, the polyethylene cord serves as a spacer for controlling the distance between the assembly of twisted wire pairs and the sheath. The air layer 5 is formed between the assembly of twisted pair wires and the sheath. This air layer is formed over substantially the entire circumference of the assembly of twisted pair wires except for the portion where the spacer 3 is located. In addition, since the polyethylene cord has an appropriate hardness, even when a large number of communication cables are stacked, the function as a spacer is maintained without being crushed, and the air layer formed on the outer periphery of the twisted pair assembly is maintained. It is possible.

  FIG. 1C shows a state in which two communication cables 10 and 11 according to the present invention are stacked. Line-shaped spacers have moderate hardness and also function as ridges that spirally extend around the outer periphery of the sheath, so when multiple communication cables are stacked, the role of controlling the spacing between adjacent communication cables Fulfill. Therefore, as shown in FIG. 1C, another air layer 12 is formed between the two adjacent communication cables 10 and 11, and this air layer is substantially the same as the communication cable except for the portion where the spacer is located. It is formed over the entire circumference. Accordingly, since a total of three air layers are interposed between the adjacent twisted wire pairs of the two stacked communication cables, it is difficult to form electrostatic coupling between the two cables, and the alien cross Talk is greatly improved.

  Next, the effect of improving alien crosstalk will be described. FIG. 2 shows a test cable used in an alien crosstalk measurement experiment. The test cable is a set of measurement cables 20 arranged at the center and six cables arranged around the measurement cable 20. These seven cables have the same structure, and the alien crosstalk from the cables 21a to 21f arranged around the measurement cable 20 arranged at the center was measured, and the added data was measured.

  FIG. 3 is a graph showing experimental results of alien crosstalk. In FIG. 3, the vertical axis represents power sum alien NEXT (Power Sum Alien Near End Cross Talk), and the horizontal axis represents frequency. In the figure, the thick solid line shows data for a communication cable in which a 2.0 mm diameter line spacer is wrapped around a twisted pair assembly, and the middle solid line shows a 1.6 mm diameter line spacer. The thinnest solid line shows the data of the communication cable in which the outer surface is covered with the aggregate of the twisted pair wire without the spacer. In the case of a communication cable that does not have a line-shaped spacer and the sheath directly covers the outer peripheral surface of the assembly of twisted pairs, alien crosstalk, which deviated significantly from the permanent link standard, was measured in a frequency band exceeding about 150 MHz. On the other hand, a communication cable wound with a line spacer with a diameter of 1.6 mm was measured to sufficiently satisfy the permanent standard even in a high frequency band. Further, in the case of a communication cable wound with a line spacer having a diameter of 2.0 mm, data sufficiently satisfying the standard value was measured even at 500 MHz. From the experimental results, by winding a linear spacer around the outer periphery of the twisted wire assembly, an air layer is formed on almost the entire periphery of the twisted wire assembly, resulting in a significant increase in alien crosstalk. Proved to be improved.

  FIG. 4 is a diagram showing the configuration of a multi-pair communication cable according to the present invention. A communication cable 30a is arranged at the center of the cable, and six communication cables 30b to 30g are gathered at equal intervals around the communication cable 30a. The outer periphery of the assembly of these seven communication cables is covered with a sheath member 31. The seven communication cables are constituted by the communication cables shown in FIG. Even in such a multi-pair type cable, an air layer is formed on the outer periphery of the assembly of twisted pair wires of each communication cable. Therefore, as shown in FIG. A three-layer air layer is interposed between the assembly of wires, and as a result, a multi-pair type communication cable with a greatly improved alien crosstalk is realized. In addition, it is also possible to arrange PE intervention instead of the communication cable 30a arranged at the center.

1 is a diagrammatic sectional view showing an example of a communication cable according to the present invention. It is a diagrammatic sectional view showing the structure of a cable used in an alien crosstalk measurement experiment. It is a graph which shows the measurement result of the alien crosstalk of the communication cable by this invention. 1 is a schematic cross-sectional view showing a configuration of a multi-pair communication cable according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Interposition 2a-2d Twisted pair wire 3 Line-like spacer 4 Sheath 5,12 Air layer 10,11 Communication cable 20 Measurement cable 20a-20f Cable 30a-30g Communication cable 31 Sheath member

Claims (4)

A communication cable suitable for signal transmission in a high-frequency band, having four storage areas for storing twisted pair wires, and having a cross-shaped cross section and a twisted pitch arranged in each of the intermediate storage areas. Are wound around the outer periphery of the assembly of the four twisted wires different from each other, the interposition and the four twisted wires, and a linear spacer wound in a spiral at a predetermined pitch. A sheath covering the outer periphery of the assembly of twisted pair wires being
A communication cable, characterized in that an air layer is formed over substantially the entire circumference except for a portion where a linear spacer is located between the outer peripheral surface of the aggregate of twisted pair wires and the sheath.   2. The communication cable according to claim 1, wherein when the conductor sizes are AWG22 to AWG26, the linear spacer is made of a columnar or hollow cylindrical dielectric material.   In the communication cable according to claim 2, as the linear spacer, a linear spacer composed of an aggregate of polyethylene, polyvinyl chloride, or cellulose fibers having a diameter of 1.6 to 2.0 mm is used. A communication cable, wherein the linear spacer is spirally wound around the outer periphery of an assembly of twisted pair wires at a twist pitch of 20 to 40 mm. In a multi-pair communication cable having an aggregate of a plurality of communication cables and a sheath member covering the outer periphery of the aggregate of the communication cables,
Each of the communication cables has four storage areas for storing twisted pair wires, and the cross section is disposed in each of the interposed storage areas having a substantially cross-shaped cross section, and four twisted pair wires having different twist pitches. A linear spacer spirally wound at a predetermined pitch on the outer periphery of the aggregate of the interposition and the four twisted wires, and a twisted wire assembly in which the linear spacers are wound A sheath covering the outer periphery of the wire, and an air layer is formed between the outer peripheral surface of the twisted pair assembly and the sheath, except for a portion where a linear spacer is located. A multi-pair communication cable characterized by

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