JPH06349344A - Communication cable - Google Patents

Abstract

PURPOSE:To prevent generation of difference in signal transmission time between pairs with a good crosstalk characteristic kept. CONSTITUTION:A communication cable 10 is formed by assembling plural pairs 12. Pairs 121-12n are respectively intertwisted at a different twisting pitch every specified distances La-Ln within a set section. The pairs 121-12n are respectively intertwisted at different twisting pitch from the next pair 12 in distances La-Lc. The electricity length every set section of the plural pairs 12 is set equally by combining the pairs 121-12n by adjusting the length of the plural pairs 12 within a set section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication cable formed by assembling a plurality of pairs, and more particularly to an improvement of a communication cable for improving the crosstalk characteristic between each pair.

[0002]

2. Description of the Related Art Generally, when transmitting a communication signal through a communication cable, (1) a communication signal in which a clock signal component is superimposed on a data signal component is sent, and a clock signal component is extracted from this communication signal on the receiving side. , A method of communicating while synchronizing with this clock signal component,
(2) A method in which a data signal and a clock signal for synchronizing the data signal are made to flow independently of each other, and the data signal is taken out and communicated at the receiving side while synchronizing with the clock signal received independently is there.
The method (1) is used, for example, in Manchester code and the like, and in the case of balanced signal transmission using a pair, it is possible to perform communication in one pair if communication is in only one direction. On the other hand, the method (2) is, for example, RS422 (EI) which is a standard of a serial transmission interface for data communication.
A standard) is used in a synchronous manner, a pair for transmitting a data signal and a pair for transmitting a clock signal are used, and a plurality of pairs are required.

In recent years, due to the improvement of the pair performance,
High-speed communication of about 0 Mbps to 100 Mbps is possible, and the method of extracting the clock signal component from the communication signal shown in (1) also enables high-speed communication. However, if higher speed communication is required in the future, it becomes difficult to perform accurate clock reproduction by the method of extracting the clock signal component shown in (1),
It is necessary to use the method of independently transmitting the data signal and the clock signal shown in (2).

The communication cable used in the method (2) is generally formed by assembling a plurality of pairs 12 as shown in FIG. Conventionally, in order to improve the crosstalk characteristic, the communication cable 10 formed in this way has a twist pitch P _{1 to} P _n (see FIG. 5) of each pair 12 _{1 to} 12 _n constituting the communication cable 10 in order to improve the crosstalk characteristic. (Refer to 5) and are gathered together. That is, pair 12 ₁
The twist pitch P ₁ of the pair 12 ₂ , the twist pitch P ₂ of the pair 12 ₂ and the twist pitch P _n of the pair 12 _n are different from each other (see FIG. 5).

[0005]

However, in the conventional communication cable, as shown in FIG. 5, each pair 12 ₁ to 12 _1
n twist pitch P ₁ to P _n (see FIG. 5) is set to be constant without changing in the longitudinal direction. In this case, the smaller the twist pitch, the longer the electrical length of the pair 12 in the cable unit length. That is, in FIG. 5, the small pitch P ₁
A twisted pair 12 _1, comparing the twisted with the pair 12 _n with a large pitch P _n, who pair 12 ₁ is longer electrical length than the pair 12 _n, 1 single communication cable 1
Within 0, the electrical length of each pair 12 _{1 to} 12 _n is different,
There is a difference in signal transmission time. Therefore, when the data signal and the clock signal are transmitted by different pairs,
A signal transmitted by a pair twisted at a small pitch has a longer arrival time, and there is a possibility that the data signal and the clock signal are out of synchronization. Specifically, 1
Even when a communication cable having a length of 00 m is formed by assembling pairs with good performance in recent years, a difference of several ns to several ns occurs in signal transmission time between each pair. Therefore, for example, when transmitting a signal of 100 Mbps,
One cycle is 20 ns, and the phase difference of the clock signal occurs in one communication cable due to the difference in transmission time between each pair. On the other hand, if the twist pitches of adjacent pairs are set to be equal to each other so that there is no difference in electrical length between the pairs, the crosstalk characteristic deteriorates, and there is a drawback that a voice or the like can be heard.

The object of the present invention is to avoid the above-mentioned drawbacks and to maintain good crosstalk characteristics in a communication cable while preventing the electrical lengths of each pair from being equal and causing a difference in signal transmission time. It is to provide a communication cable that can.

[0007]

As a first means for solving the above problems, the present invention provides a communication cable comprising a plurality of pairs of adjacent pairs with different twist pitches. A communication cable characterized in that each pair of a plurality of pairs is twisted at different twist pitches at predetermined intervals within a certain section in the longitudinal direction, and the electrical lengths of the plurality of pairs are set to be equal to each other. Is provided.

As a second means for solving the above-mentioned problems, the present invention provides a communication cable in which a plurality of pairs of adjacent pairs with different twist pitches are assembled, To provide a communication cable characterized in that each pair is twisted with a twisting pitch that continuously changes in a constant section in the longitudinal direction, and the electrical lengths of a plurality of pairs in a constant section are set to be equal. is there.

[0009]

As described above, when each pair is twisted with a different twist pitch at a predetermined interval in a constant section in the longitudinal direction or with a twist pitch that continuously changes at a constant section, a twist different from an adjacent pair is obtained. Since it is possible to adjust the electrical length of each pair within a certain section while twisting them at a pitch, it is possible to equalize the electrical length between each pair while maintaining good crosstalk characteristics, resulting in a difference in signal transmission time. It can be prevented from occurring. Further, even if the communication cable is cut as necessary, since the electrical lengths are set equal to each other in a certain section, there is no great difference in signal transmission time.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described in detail. FIG. 1 shows a communication cable 10 of the present invention. In the embodiment shown in (1), the plurality of assembled pairs 12 are covered with a push winding 16 via an intervening 14 provided as necessary, and a sheath 18 is formed on the push winding 16. The communication cable 10 may be a flat cable formed by arranging a plurality of pairs 12 in a substantially planar arrangement instead of the round communication cable 10 shown in FIG.
In addition, although the communication cable 10 is formed of five pairs 12 in FIG. 1, the communication cable 10 may be formed of any other appropriate number as necessary.

As shown in FIG. 2, each pair 12 is formed by twisting two insulated wires 20 each having a conductor coated with an insulating layer. As the conductor, for example, annealed copper wire or the like is used.

As shown in FIG. 3, each of the pairs 12 _{1 to} 12 _n of the plurality of pairs 12 has a predetermined interval L _{a to} L _c (see FIG. 3) within a constant section L (see FIG. 3) in the longitudinal direction. ) Are twisted at different twist pitches P (see FIG. 3). Incidentally, within each predetermined interval L _a to L _c (see FIG. 3), the twisting pitch P (see FIG. 3) is constant. Specifically, for example, taking the pair 12 _n as an example, as shown in FIG. 3, the twist pitch P _n1 between the predetermined intervals L _a ,
The twist pitch P _n2 between the intervals L _b and the predetermined interval L _c
The twist pitch P _n3 between the two is different.
This is because the other pairs 12 ₁ , 12 are
_The same applies to ₂ .

Further, each of the plurality of pairs 12 12 ₁ to 12 _1
n is a predetermined section L _{a to} L _c (see FIG. 3) within a fixed section L (see FIG. 3) in the longitudinal direction, and adjacent pairs 12 are twisted at different twist pitches P (see FIG. 3). Have been combined. That is, in the present invention, as described above, are made different constant interval L predetermined intervals in a (see FIG. 3) L _a to L _c (see FIG. 3) twist every pitch P (see FIG. 3) Therefore, the twist pitch P (see FIG. 3) of each pair 12 _{1 to} 12 _n is set so that the twist pitch P (see FIG. 3) of the adjacent pair 12 is different within one interval.
Can be appropriately combined. Specifically, section L
_{Taking c} as an example, as shown in FIG.
The twist pitch P _{13 at} the interval L _c of ₁ is different from the twist pitch P _{23 at} the interval L _c of the pair 12 ₂ and the twist pitch P _{n3 at} the interval L _c of the pair _n . This also applies to the other intervals L _a and L _c . In this way, each pair 12 is twisted with another adjacent pair 12 at a pitch P (see FIG. 3) different from that of the other pair 12, so that good crosstalk characteristics can be obtained.

Further, in the present invention, the electrical lengths of the constant intervals L (see FIG. 3) of the plurality of pairs 12 are set equal. That is, each pair 12 ₁ through 12 _n is because it is twisted in the longitudinal direction of the predetermined distance L _a to L _c (see FIG. 3) different twist every pitch P (see FIG. 3), adjacent in each interval While twisting at a twist pitch different from that of the pair 12, the intervals L _{a to} L _{c are provided for} each pair 12 _{1 to} 12 _n.
(See FIG. 3) By appropriately selecting and combining the twist pitch sizes, the length within a certain section L (see FIG. 3) is adjusted so that the electrical lengths of each pair 12 _{1 to} 12 _n are mutually changed. Can be equal. Specifically, one to one
2 ₁ and the insulating line 20 ₁ constituting the pair 12 ₂ insulated wire 20 ₂ constituting the, also pairs 12 _n constituting the insulating line 20 _n
All have substantially the same length in the constant section L (see FIG. 3) and have the same electrical length. Therefore, each pair 12 _{1 to} 1
There is no difference in signal transmission time of 2 _n .

The plurality of pairs 12 are arranged in this fixed section L (see FIG. 3).
By repeating pairs 12 of the
Is made. In this case, electricity is generated every fixed section L (see FIG. 3).
These are combined because the lengths are set equal.
Even in the combined section, the electrical length is the same, and communication is inevitable.
Even in the total length of the cable 10, each pair 12₁ Through 12 _n 
Have the same electrical length and no difference in signal transmission time.
Yes. Therefore, also, if necessary, disconnect the communication cable 10.
Even if it is turned off, in particular, each fixed section L (see FIG. 3).
If you cut it at the division of
There is no difference. In this case, each section L (see Fig. 3)
Mark the sheath 18 at the delimiter part
This makes it easy to determine the optimum cutting point.
It is convenient. Moreover, in the embodiment of FIG.
(See Fig.3)
However, as long as there is a plurality, other appropriate numbers may be used.

Next, FIG. 4 shows another embodiment of the present invention, in this embodiment each pair 12 of a plurality of pairs 12.
₁ and 12 ₂ are twisted with a twisting pitch that continuously changes for each fixed section L (see FIG. 4) in the longitudinal direction. In this case, the changing rate of each twist pitch is made different so that the twist pitches of the adjacent pairs 12 ₁ and 12 ₂ are different. That is, as shown in FIG. 4, if a twisting pitch change rate 12 ₁ is large and a twisting pitch change rate pair 12 ₂ is adjacent to each other, the twisting pitches of the two are different from each other. Good crosstalk characteristics can be obtained.

Also in this embodiment, a plurality of pairs 1
It is necessary to set the electric lengths of the two constant sections L (see FIG. 4) equal. In this case, by appropriately selecting and combining the rate of continuous change of the twisting pitch for each pair 12 ₁ and 12 ₂ , while adjoining the adjacent pair 12 at different twisting pitches, a fixed section L (see FIG. 4) The length within can be adjusted to make the electrical length of each pair 12 ₁ , 12 ₂ equal. Specifically, the insulated wire 20 ₁ constituting the pair 12 _1, insulated wire 20 ₂ constituting the pair 12 ₂ is substantially the same length in a certain section L (see FIG. 4), it is equal to the electrical length . Therefore, there is no difference in signal transmission time between each pair 12 ₁ and 12 ₂ .

Lastly, the communication cable 10 of the present invention is not used only for separately transmitting a data signal and a clock signal as described at the beginning, but may be used for other purposes such as a plurality of data signals. Can be used for various purposes, such as transmitting each pair for each pair, synthesizing these data signals on the receiving side, and performing further high-speed communication.

[0019]

According to the present invention, as described above, each pair is twisted at a twist pitch that is different at a predetermined interval in a constant section in the longitudinal direction or continuously changes at a constant section. Therefore, it is possible to adjust the length of each pair within a certain section while twisting with a twist pitch different from that of the adjacent pair, so that the electrical length between each pair is made equal while maintaining good crosstalk characteristics. Therefore, it is possible to prevent a difference in signal transmission time from occurring, which is a real advantage. In addition, even when the communication cable is cut as necessary, the electrical lengths are set to be equal for each fixed section, so that there is no large difference in signal transmission time.

[Brief description of drawings]

FIG. 1 is a perspective view of an end portion of a communication cable of the present invention.

FIG. 2 is a sectional view of a pair used in the present invention.

FIG. 3 is a schematic view showing a twisted state of a pair used in the present invention.

FIG. 4 is a schematic view showing a twisted state of a pair used in another embodiment of the present invention.

FIG. 5 is a schematic diagram showing a twisted state of a pair used in a conventional communication cable.

[Explanation of symbols]

10 Communication cable 12 pair 14 interposed 16押巻-out 18 sheath 20 insulated wire L constant interval L _a, L _b, L _c predetermined interval

Claims (2)

[Claims] 1. A communication cable comprising a plurality of pairs of adjacent pairs having different twist pitches, wherein each pair of the plurality of pairs has a different twist pitch at predetermined intervals within a certain section in the longitudinal direction. And the electrical length of each of the plurality of pairs of constant sections is set to be equal. 2. A communication cable comprising a plurality of pairs of adjacent pairs having different twist pitches, wherein each pair of the plurality of pairs has a twist pitch which continuously changes at certain intervals in the longitudinal direction. A communication cable in which the electrical lengths of the plurality of pairs are twisted and set to be equal to each other in the constant section.