JP2008300248A - Communication cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently reduce alien crosstalk without thickening an outer diameter, and to facilitate lead forming work in a communication cable used for high speed signal transmission. <P>SOLUTION: This communication cable is equipped with one or more pairs of stranded wire pairs 2, a covering pipe 3 to cover each stranded wire pair 2, and a sheath 5 forming an outermost periphery while covering the covering pipe 3. The covering pipe 3 has a hollow structure, and an air gap is formed between the inner peripheral part of the covering pipe 3 and the stranded wire pair 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication cable used for high-speed signal transmission of, for example, several Mbit / sec or more.

  Conventionally, various communication cables used for high-speed signal transmission have been proposed. For example, Patent Document 1 describes the structure of a transmission path for signal transmission in the GHz band and the structure of a connector used for signal transmission in the GHz band. This is a structure in which an insulator is covered with a dielectric to confine an electromagnetic field.

  In addition, the communication cable (shielded communication cable) that enables high-speed signal transmission described in Patent Document 2 has two or more blocks each made of two or more core wires covered with an insulator. The outer side is configured to be covered with a solid material having a dielectric constant equivalent to, or effectively, a low dielectric constant.

  The communication cable described in Patent Document 3 and the multi-pair communication cable using the communication cable are configured by arranging four twisted wires and two intervening intervening shafts alternately twisted. .

  Patent Literature 4 describes a communication cable (UTP communication cable) in which a pair of interposition shafts interposed between a pair of twisted wires are different.

  Further, in Patent Document 5, a plurality of conductive wire pairs covered with an insulator are arranged around a deformed interposed shaft, and the movement of each wire pair is constrained by the deformed interposed shaft and covered with a sheath. A twisted pair communication cable is described.

JP 2005-33495 A JP 2000-48651 A JP 2001-67947 A JP 2006-260897 A Japanese Patent Laid-Open No. 11-283449

  By the way, in the conventional communication cables described in Patent Document 1 and Patent Document 2 described above, it is said that crosstalk (crosstalk) can be reduced by fixing the twisted pair wire with a dielectric. . Certainly, the effect of reducing the crosstalk is recognized in the communication cable in which the twisted pair wire is completely fixed. However, such a communication cable has a problem that it is difficult to process the lead. In addition, when more precise crosstalk reduction is required, it is difficult to obtain a sufficient effect with these communication cables.

  Moreover, in the conventional communication cables described in Patent Document 3, Patent Document 4 and Patent Document 5, by interposing an interposition shaft between the twisted wires, by fixing the relative position between the twisted wires, I try to reduce crosstalk. However, such a communication cable has a problem that the outer diameter becomes thick.

  FIG. 5 is a cross-sectional view illustrating crosstalk.

  The crosstalk here mainly refers to alien crosstalk. As shown in FIG. 5, alien crosstalk is not crosstalk that occurs in the same communication cable 101, but crosstalk between the other communication cables 102 and 103 adjacent to this communication cable 101. .

  In general, when there are a plurality of twisted wire pairs in a communication cable, the twisted wire pairs are twisted with different twist pitches for each twisted wire pair in order to reduce crosstalk between the twisted wire pairs. However, when communication cables having the same configuration are adjacent to each other, alien crosstalk occurs because the twist pitches of the corresponding twisted wire pairs are the same.

  FIG. 6 is a cross-sectional view showing a configuration of a conventional communication cable in which crosstalk is reduced.

  As a countermeasure against such alien crosstalk, a communication cable 101 has been proposed in which the cross-sectional shape is not circular but close to an ellipse as shown in FIG. In this communication cable, when installed, the major axis direction of the ellipse of the cross-sectional shape becomes the horizontal direction, so when a plurality of communication cables are arranged in parallel, the interval between the twisted pair of each communication cable must be secured. Can reduce crosstalk. However, this communication cable also has a problem that the substantial outer diameter is increased.

  There has also been proposed a communication cable in which crosstalk is reduced by applying a shielding member. Although a reduction in crosstalk due to the shielding member is recognized, there is a problem that the processing of the shielding member becomes complicated when wiring the communication cable.

  Therefore, the present invention is proposed in view of the above-described circumstances, and is a communication cable used for high-speed signal transmission, and alien crosstalk is sufficiently reduced without increasing the outer diameter. It is another object of the present invention to provide a communication cable that can be easily processed.

  In order to solve the above-described problems and achieve the above object, a communication cable according to the present invention has any one of the following configurations.

[Configuration 1]
A communication cable used for signal transmission, comprising at least one pair of stranded wires made of a conductor coated with an insulator, a sheath tube covering each strand wire pair, and a sheath covering the sheath tube and serving as the outermost peripheral portion The cladding tube has a hollow structure, and a gap is formed between the inner periphery of the cladding tube and the twisted wire pair.

[Configuration 2]
The communication cable having the configuration 1 is characterized in that at least one notch (notch) is formed on the outer peripheral portion of the cladding tube.

[Configuration 3]
In the communication cable having the configuration 1, the cladding tube is characterized in that two notches are formed on the outer peripheral portion or the inner peripheral portion at positions facing each other via the central axis. .

[Configuration 4]
In the communication cable having any one of Configurations 1 to 3, the communication cable has a plurality of twisted wire pairs covered by a cladding tube, and these twisted wire pairs are twisted together to form a twist pitch between the twisted wire pairs. Is characterized by a random change in the longitudinal direction.

[Configuration 5]
In the communication cable having any one of Configurations 1 to 3, the communication cable has a plurality of twisted wire pairs covered with a cladding tube, and these twisted wire pairs are gathered together by twisting, and the twist direction of the twisted wire pairs. Is characterized by alternating in the right and left directions with respect to the longitudinal direction.

[Configuration 6]
In the communication cable having any one of Configurations 1 to 3, the communication cable has a plurality of twisted wire pairs covered by a cladding tube, and these twisted wire pairs are twisted together to form a twist pitch between the twisted wire pairs. Is characterized by being randomly changed in the longitudinal direction and the twisting direction of the twisted wire pairs alternately changing in the right and left directions with respect to the longitudinal direction.

[Configuration 7]
In the communication cable having the configuration 4 or the configuration 6, the twist pitch between the twisted wire pairs is randomly changed so that the maximum pitch and the minimum pitch are ± 10% or more with respect to the specified pitch. It is characterized by.

[Configuration 8]
In the communication cable having any one of Configurations 1 to 7, the material forming the insulator and the cladding tube is a material having a dielectric loss tangent of 0.0002 or less.

[Configuration 9]
In the communication cable having any one of Configurations 1 to 8, the insulator has a thickness of 0.3 mm or less.

  In the communication cable according to the present invention having the configuration 1, the cladding tube covering each twisted wire pair has a hollow structure, and a gap is formed between the inner periphery of the cladding tube and the twisted wire pair. Therefore, alien crosstalk can be sufficiently reduced without increasing the outer diameter.

  In the communication cable according to the present invention having the configuration 2, at least one notch (notch) is formed on the outer peripheral portion of the cladding tube, so that the lead processing can be facilitated.

  In the communication cable according to the present invention having the configuration 3, the cladding tube has two notches formed in the outer peripheral portion or the inner peripheral portion at positions opposed to each other via the central axis. Processing can be facilitated.

  In the communication cable according to the present invention having the configuration 4, a plurality of twisted wire pairs are gathered together and the twist pitch of the twisted wire pairs changes randomly in the longitudinal direction. Generation of alien crosstalk when a plurality of cables are arranged in parallel can be prevented.

  In the communication cable according to the present invention having the configuration 5, a plurality of twisted wire pairs are twisted and gathered together, and the twist direction of the twisted wire pairs alternately changes in the right direction and the left direction with respect to the longitudinal direction. Therefore, it is possible to prevent the occurrence of alien crosstalk when a plurality of communication cables are arranged in parallel.

  In the communication cable according to the present invention having the configuration 6, a plurality of twisted wire pairs are gathered to be twisted together, and the twist pitch of the twisted wire pairs is randomly changed in the longitudinal direction. Since the twisting direction of the wire pairs alternately changes in the right direction and the left direction with respect to the longitudinal direction, the occurrence of alien crosstalk can be reliably prevented when a plurality of communication cables are arranged in parallel.

  In the communication cable according to the present invention having the configuration 7, the twist pitch between the twisted wire pairs is randomly changed in a range where the maximum pitch and the minimum pitch are ± 10% or more with respect to the specified pitch. The occurrence of alien crosstalk when a plurality of communication cables are arranged in parallel can be reliably prevented.

  In the communication cable according to the present invention having the configuration 8, since the material forming the insulator and the cladding tube is a material having a dielectric loss tangent of 0.0002 or less, it is excellent in high-speed signal transmission of several Mbit / sec or more. Characteristics are realized.

  In the communication cable according to the present invention having the configuration 9, since the insulator has a thickness of 0.3 mm or less, the outer diameter of the communication cable is not increased.

  That is, the present invention provides a communication cable used for high-speed signal transmission, in which alien crosstalk is sufficiently reduced without increasing the outer diameter, and the lead-out process is facilitated. Is something that can be done.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration of a communication cable according to the present invention.

  As shown in FIG. 1, the communication cable according to the present invention has a plurality of twisted wire pairs 2 in which a pair of conductive wires covered with an insulator 1 are twisted together. These twisted wire pairs 2 are covered with a cladding tube 3. The cladding tube 3 has a hollow structure, and a gap is formed between the inner periphery of the cladding tube 3 and the twisted wire pair 2. The twisted wire pairs 2 covered by the cladding tube 3 are gathered around the interposed shaft 4 around the interposed shaft 4 and twisted together. Further, the outermost periphery of the communication cable is covered with a sheath 5. The sheath 5 is made of a polymer compound material having good wear resistance and heat resistance.

  Further, at least one notch (notch) 6 is formed on the outer peripheral portion of the cladding tube 3. The notch 6 is formed in the longitudinal direction (axial direction) of the cladding tube 3. The notch 6 may be formed on either the outer peripheral portion or the inner peripheral portion of the cladding tube 3, and is preferably formed at two locations facing each other with the central axis of the cladding tube 3. Moreover, it is desirable that the notch 6 be sufficiently smaller than the outer diameter of each twisted wire pair 2 so that the arrangement of each twisted wire pair 2 is not disturbed. Since the notch 6 is formed in the cladding tube 3, the workability at the time of opening is improved.

  As the material for the insulator 1 and the cladding tube 3, it is desirable to use polyethylene having excellent electrical characteristics with a low dielectric constant and dielectric loss tangent at high frequencies, and realizing excellent characteristics in high-speed signal transmission of several Mbit / sec or more. Therefore, it is preferable to use a material having a dielectric loss tangent of 0.0002 or less. Moreover, in order not to increase the outer diameter of the communication cable as much as possible, it is desirable that the thickness of the insulator 1 be 0.3 mm or less.

  And although each strand wire pair 2 covered with the cladding tube 3 is gathered centering on the interposition axis | shaft 4, it is preferable to change the twist pitch of each strand wire pair 2 at random about a longitudinal direction. In this case, it is desirable that the twist pitch between the twisted wire pairs 2 is randomly changed in a range where the maximum pitch and the minimum pitch are ± 10% or more with respect to the specified pitch. By changing the twisting pitch between the twisted wire pairs 2 in this way, it is possible to prevent the occurrence of alien crosstalk when a plurality of communication cables are arranged in parallel.

  Moreover, you may make it the twist direction of each strand wire pair 2 change to a right direction and a left direction alternately with respect to a longitudinal direction. In this case, the twisting directions of the twisted wire pairs 2 may be changed alternately, and the twisting pitch of the twisted wire pairs 2 may be randomly changed in the longitudinal direction. Thus, by alternately changing the twisting direction of the twisted wire pairs 2, it is possible to prevent the occurrence of alien crosstalk when a plurality of the communication cables are arranged in parallel.

〔Example〕
As an example of the present invention, a communication cable was prepared as follows. A soft copper wire having an outer diameter of 0.57 mm was used as the conducting wire, high-density polyethylene was used as the insulator 1, and the outer diameter of the insulator 1 was set to 1.0 mm. This high-density polyethylene had a dielectric constant of 2.3 and a dielectric loss tangent of 0.0002 or less. The cladding tube 3 was formed of the same high-density polyethylene as the material of the insulator 1 with a thickness of 0.2 mm, a width of the notch 6 of 0.5 mm, and a depth of the notch 6 of 0.1 mm. The interposed shaft 4 was made of polyethylene having an outer diameter of 1.0 mm. Four twisted wire pairs 2 were assembled, and the twist pitch between the twisted wire pairs 2 was randomly changed in the longitudinal direction within a range of 200 ± 20 mm based on the value calculated from the random number table. The sheath 5 was made of PVC, had a thickness of 0.5 mm, and an outer diameter of 6.8 mm.

  FIG. 2 is a graph showing the worst value of power sum alien crosstalk in the communication cable according to the present invention and the conventional communication cable.

  FIG. 3 is a graph showing an average value of power sum alien crosstalk in the communication cable according to the present invention and the conventional communication cable.

  1 MHz to 600 MHz for the communication cable according to the present invention configured as described above and the conventional communication cable, that is, the communication cable that does not have the cladding tube 3 and has a constant twist pitch between the twisted wire pairs 2. The power sum alien crosstalk was measured. The worst value in the measurement result of power sum alien crosstalk is shown in FIG. 2, and the average value is shown in FIG.

  FIG. 4 is a cross-sectional view showing a method for measuring alien crosstalk.

  As shown in FIG. 4, the measurement of alien crosstalk is performed in a state where six communication cables B having the same structure are arranged in parallel around the communication cable A to be measured, and these cables are bound by a string. Was measured in a state of simulated wire drawing.

  As shown in FIGS. 2 and 3, the communication cable according to the present invention exhibits superior characteristics as compared with the conventional communication cable in the band of 300 MHz or more in both the worst value and the average value of crosstalk.

[Other Examples]
The communication cable according to the present invention is not limited to the materials in the above-described embodiments, and can be configured using various materials. For example, as for the conducting wire, not only an annealed copper wire but also a tin-plated annealed copper wire, a silver-plated annealed copper wire, a copper alloy wire (including plating), and the like are conceivable. Moreover, as a material which comprises the insulator 1, the cladding tube 3, the interposed shaft 4, and the sheath 5, not only polyethylene but bridge | crosslinking polyethylene, a polypropylene, a fluororesin, and various other polymeric materials can be used. Further, the intervening shaft 4 can have various shapes such as a cross-shaped cross section or a curved shape. Alternatively, the interposed shaft 4 may not be provided.

It is sectional drawing which shows the structure of the communication cable which concerns on this invention. It is a graph which shows the worst value of the electric power sum alien crosstalk in the communication cable which concerns on this invention, and the conventional communication cable. It is a graph which shows the average value of the electric power sum alien crosstalk in the communication cable which concerns on this invention, and the conventional communication cable. It is sectional drawing which shows the measuring method of alien crosstalk. It is sectional drawing explaining a crosstalk. It is sectional drawing which shows the structure of the conventional communication cable which reduced crosstalk.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulator 2 Stranded wire pair 3 Cladding tube 4 Interposition shaft 5 Sheath 6 Notch

Claims (9)

A communication cable used for signal transmission,
One or more pairs of stranded wires consisting of conductive wires coated with an insulator;
A cladding tube covering each of the twisted wire pairs;
A sheath that covers the cladding tube and serves as an outermost periphery;
The said cladding tube is a hollow structure, Comprising: The space | gap is formed between the inner peripheral part of this cladding tube, and the said twisted wire pair. The communication cable characterized by the above-mentioned. The communication cable according to claim 1, wherein at least one notch is formed in an outer peripheral portion of the cladding tube. 2. The communication cable according to claim 1, wherein two notches are formed in the cladding tube at positions facing the outer peripheral portion or the inner peripheral portion with a central axis therebetween. A plurality of the twisted wire pairs covered by the cladding tube, and these twisted wire pairs are assembled by being twisted together,
The communication cable according to any one of claims 1 to 3, wherein a twist pitch between the twisted wire pairs is randomly changed in a longitudinal direction. A plurality of the twisted wire pairs covered by the cladding tube, and these twisted wire pairs are assembled by being twisted together,
The communication cable according to any one of claims 1 to 3, wherein a twist direction of the twisted wire pairs is alternately changed in a right direction and a left direction with respect to a longitudinal direction. A plurality of the twisted wire pairs covered by the cladding tube, and these twisted wire pairs are assembled by being twisted together,
The twist pitch between the twisted wire pairs changes randomly in the longitudinal direction, and the twist direction between the twisted wire pairs alternately changes in the right and left directions in the longitudinal direction. The communication cable according to any one of claims 1 to 3. The twist pitch between the twisted wire pairs is randomly changing in a range in which the maximum pitch and the minimum pitch are ± 10% or more with respect to the specified pitch. 6. The communication cable according to 6. The communication cable according to any one of claims 1 to 7, wherein the material forming the insulator and the cladding tube is a material having a dielectric loss tangent of 0.0002 or less. The communication cable according to any one of claims 1 to 8, wherein the insulator has a thickness of 0.3 mm or less.

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