JPH08321220A - Multi-pair cable signal transmission line - Google Patents

Abstract

PURPOSE: To provide a multi-pair cable which can lessen dispersion in the transmission lag time for a transmission path as a whole, suppress the difference in the transmission lag time. and secures a good crosstalk characteristic. CONSTITUTION: At least two of multi-pair cable A formed by subjecting a plurality of pair strands (a) to a gathered twining are conected. and the pair strands (a) are arranged so that strands having different rate of twining-in adjoin one another. The connection of pair strands (a) with each other is made so that the transmission lag times for the whole signal transmission path of the connected pair strands become the same as much as practicable on the basis of the transmission lag time value per unit length of each pair strand (a) previously measured before the connection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-pair cable signal transmission line suitable for a signal transmission line of electronic equipment such as a computer and its peripheral equipment.

[0002]

2. Description of the Related Art With the advanced development of electronic devices such as computers and their peripheral devices, electric wires and cables used in this field are required to have high performance and high reliability. In particular, in parallel transmission of digital signals using a multi-pair cable, variations in characteristic impedance and deviations in the arrival time of transmission pulses are becoming strict as the signal transmission speed increases.

For example, US ANSI X3T9.3 H
According to the SC / HIPPI interface standard, the difference in propagation delay time, which is represented by the difference between the maximum value and the minimum value of the propagation delay time of each twisted pair in the same cable, is 0.13 ns / m.
Similarly, in the SCSI-3 parallel interface, the propagation delay time difference is 0.15 ns /
It is defined as m.

[0004]

However, in the conventional multi-pair cable for computers, there is no regulation on the propagation delay time difference, and the one usually used has a propagation delay time difference of about 0.3 ns / m. . Propagation delay time is
It is determined by the effective relative permittivity around the conductor, and particularly in a multi-pair cable having a shield layer, the closer the shield layer is to the metal, the longer the propagation delay time. Thus, the propagation delay time differs depending on which twisted layer of the multi-pair cable each twisted pair wire is, and is a factor that causes a difference in propagation delay time.

On the other hand, the multi-pair cable used for this parallel transmission application is required to have good crosstalk characteristics. In order to improve this crosstalk characteristic, it is indispensable to make a difference in the twisting ratio of each pair of adjacent twisted wires, but of course, there is an adverse effect of increasing the propagation delay time difference.

An object of the present invention is to solve the above problems and to provide a multi-pair cable capable of reducing variations in propagation delay time as a whole of a transmission line, suppressing a difference in propagation delay time, and ensuring good crosstalk characteristics. It is what

[0007]

In order to achieve the above object, a multi-pair cable signal transmission line according to claim 1 of the present invention is at least two multi-pair cables in which a plurality of twisted pair wires are collectively twisted.
A multi-pair cable signal transmission line connecting books, wherein the plurality of twisted pair wires are arranged such that twisted wires having different twist rates are adjacent to each other, and the connection between the twisted wires is Based on the pre-measured propagation delay time value per unit length of each twisted pair before connection, the propagation delay time value for the entire signal transmission line of each twisted pair is made to be the same as much as possible. It is characterized by

The invention of claim 2 is a multi-pair cable signal transmission line according to claim 1, wherein two multi-pair cables are connected at a substantially central portion of the entire length of the signal transmission line. is there.

Further, the invention of claim 3 is the multi-pair cable signal transmission line according to claim 1 or 2, wherein the multi-pair cables are connected to each other through a connector.

[0010]

The multi-pair cable signal transmission line of the present invention maintains good crosstalk characteristics because the twisting rates of the adjacent twisted pair wires are different, and more than two multi-pair cables are connected. , Select based on the propagation delay time value per unit length of each twisted pair before connection so that the propagation delay time of the paired twisted pair after connection will be as uniform as possible over the entire signal transmission path. Since the twisted pair wires are connected to each other, the propagation delay time difference in the entire transmission line can be suppressed to be extremely small.

In the multi-pair cable of the present invention, a plurality of twisted pair twisted wires of an insulated conductor obtained by coating a conductor with an insulator such as polyethylene are twisted into a plurality of layers and assembled. The multi-pair aggregated twisted wire composed of the assembled twisted pair wires is wound around a buffer layer, a shield layer is arranged on the outer periphery thereof, and a sheath is further covered. In the multi-pair cable according to the present invention, in order to satisfy the crosstalk characteristic, the twisted pair wires are arranged so that the twisted wires having different twist rates are adjacent to each other.
The shield layer is formed by braiding or laterally winding a conductor wire of copper, aluminum or the like plated with tin, nickel, silver or the like, or a conductor wire of bare copper, aluminum or the like. Alternatively, it is formed by arranging a metal tape made of aluminum, copper, or the like, or a laminated tape of the metal tape and plastic in a single layer or a plurality of layers. Further, this shield layer may be a combination of the above braid, horizontal winding, and metal tape depending on the application. Furthermore, a sheath of polyethylene, polyvinyl chloride, or the like is applied to the outer layer of the shield layer to complete the multi-pair cable.

[0012] In this multi-pair cable, the twisting rate between adjacent twisted pair wires is made different in order to satisfy the crosstalk characteristic, and the difference in the twisting rate appears as variations in propagation delay time. . Therefore, in the present invention, the entire signal transmission path is not configured by one multi-pair cable having a propagation delay time difference. For example, the multi-pair cable is cut at the middle of the use length to form two multi-pair cables, Based on the measured propagation delay time value per unit length of each twisted pair before connection, one cable should be used so that the propagation delay time value in the entire signal transmission line of each twisted pair is the same as much as possible. A twisted pair cable with a long propagation delay time per unit length, that is, a high twist rate, is connected to a twisted pair cable with a short propagation delay time per unit length, that is, a low twist rate, and In addition, the twisted pair wire with short propagation delay time per unit length of one cable is connected to the twisted pair wire with long propagation delay time of the other cable, so the propagation delay time difference should be minimized for the entire transmission line. Is possible. Note that the propagation delay time of each twisted pair in a multi-pair cable is determined by the effective relative permittivity around the conductor, and the distance from the shield layer is very effective.Therefore, connection should be made between twisted pairs located in the same twisted layer. Will be done. Further, it is desirable to adopt a connector in order to avoid complicated connection and poor connection.

The propagation delay time depends on the differential TDR (Ti
me Domain Reflectormeter) and the crosstalk characteristics are measured by the oscillator and level meter using a transformer that matches the characteristic impedance of the measuring instrument and the cable.

[0014]

EXAMPLES Examples of the present invention and comparative examples will be described in detail below. FIG. 1 shows a multi-pair cable A used in Examples of the present invention and Comparative Examples. This cable A has 12 pairs of twisted wires a
Is twisted into two layers to form a multi-pair assembled stranded wire b, and a buffer layer c, shield layers d ₁ and d ₂ , are provided on the outer periphery of the multi-pair assembled stranded wire b.
The sheath e is sequentially provided. The upper number in the circle showing the twisted pair a is a pair number for identification, and the lower number is the twist pitch (mm). As shown in FIG. 2, each twisted pair a has an insulating strand h formed by applying an insulating coating g to a conductor f.
Two of them are twisted together.

The dimensions and materials of each part are as follows. Conductor f: A stranded conductor obtained by twisting seven tin-plated copper wires having an outer diameter of 0.127 mm, and a standard outer diameter of 0.38 mm. Insulation coating g: Polyethylene (fluorine resin, polyvinyl chloride, etc. can be used) Insulation wire h: Outer diameter 0.70 mm Pair twisted wire a: Insulation wire h is shown in the lower row of the circle Twisted with a twisted pitch. Multi-pair assembled stranded wire b: The center layer is left-handed with a twist pitch of 50 mm, and the outermost layer is right-handed with a twist pitch of 80 mm. Buffer layer c: A polyester non-woven tape having a thickness of 0.2 mm is wound in a 1/4 wrap. Shield layer d ₁ : 25 μm thick aluminum-laminated polyester tape is horizontally wound in a 1/4 wrap. Shield layer d ₂ : outer diameter 0.12 mm, tin-plated annealed copper wire 5
Braided with 16 books. Sheath e: 0.8 mm thick flexible polyvinyl chloride

[Example] The twist pitch of the twisted pair a is 9 m
m, 14 mm and 23 mm, and the twist pitch of the center layer (pair number 10 to 12) of the multi-pair assembled twisted wire b is 5
0mm, twist pitch of outermost layer (pair number 1-9) is 80m
As shown in Table 1, the total twisting rate Y, the twisting rate yt of the twisted pair wire and the twisting rate yc of the collective twist are as shown in Table 1, and the polyester nonwoven fabric has a thickness of 0.2 mm and a width of 25 mm. The tape was rolled horizontally in 1/4 wrap. Where the total twist rate Y
Is represented by the product of the twisted pair twist ratio: yt and the collective twist twist ratio: yc.

[0017]

## EQU1 ## Y = yt.times.yc (1) The twisted pair ratio yt of the twisted pair wire is expressed by Equation 2.

[0018]

## EQU2 ## yt = {Pt ² + (π × dt) ² } ^1/2 / Pt (2) Pt: Pitch of twisted pair dt: Distance between conductor centers Also, the twisting rate yc of the set twist is , Expressed by Equation 3.

[0019]

## EQU3 ## yc = {Pc ² + (π × dc) ² } ^1/2 / Pc (3) Pc: Collective twist pitch dc: Layer core diameter

10 m of the completed cable A, 5 at the center point
Cut at m. At this breaking point, each twisted wire was connected as shown in Table 2 to form a multi-pair cable signal transmission line. When the propagation delay time Tpd of each of the connected twisted wires was measured, the propagation delay time shown in Table 2 was obtained as a whole. Propagation delay time difference is 0.60 ns / 1
It was 0 m. Further, as shown in Table 3, the near-end crosstalk characteristic at 100 MHz and 10 m maintained a sufficient characteristic.

(Comparative Example 1) As in the example, the twist pitch of the twisted pair a was selected to be 3 sets of 9 mm, 14 mm and 23 mm, and the center layer (pair number 10-12) of the multi-pair assembled twisted wire b was selected. The twist pitch is 50 mm, the twist pitch of the outermost layer (pair numbers 1 to 9) is 80 mm, and the total twist ratio Y, twist ratio yt of twisted wires, and twist ratio yc of collective twist are shown in Table 4. Then, as the buffer layer c, a polyester non-woven tape having a thickness of 0.2 mm and a width of 25 mm was horizontally wound in 1/4 wrap.

The propagation delay time Tpd at 10 m was measured for all the twisted pair wires of the completed multi-pair cable signal transmission line, and the results shown in Table 4 were obtained. Propagation delay time difference is 1.6
It was 0 ns / 10 m. Also, 100MHz, 10m
The near-end crosstalk characteristics in Table 1 were as shown in Table 5.

(Comparative Example 2) With the same structure as in Comparative Example 1 described above, the twist pitch of the twisted pair a was set to 14 mm in all pairs, and the center layer (pair number 10 to 12) of the multi-pair aggregated twisted wire b was formed. The twist pitch is 50 mm, the twist pitch of the outermost layer (pair numbers 1 to 9) is 80 mm, and the total twist rate Y and twist rate of the twisted pair yt
Further, as shown in Table 6, the twisting ratio yc of the collective twist, a polyester nonwoven fabric tape having a thickness of 0.2 mm and a width of 25 mm was horizontally wound in a 1/4 wrap as the buffer layer c.

The propagation delay time Tpd at 10 m was measured for all the twisted pair wires of the completed multi-pair cable signal transmission line, and the results shown in Table 7 were obtained. As the propagation delay time difference,
The result was 0.60 ns / 10 m, which was equivalent to that of the example. However, the near-end crosstalk characteristics at 100MHz and 10m are:
As shown in Table 6, it was significantly deteriorated as compared with Comparative Example 1.

From the above results, comparing Example 1 and Comparative Example 1 having the same structure and the same twist pitch,
In the case of the example, based on the propagation delay time value per unit length measured by cutting one multi-pair cable in the middle,
The pair of twisted wires having a large propagation delay time and the pair of twisted wires having a small propagation delay time are connected to each other with intermediate values, so that the propagation of Comparative Example 1 includes one multi-pair cable that is not connected in the middle. Delay time difference 1.60ns / 10m is 0.60
It was found that it was improved to ns / 10m.

Further, the twisted pair is connected to the twisted pair with a large difference in propagation delay time, which results in 100
It was also revealed that there is no change in the near-end crosstalk characteristics at MHz and 10 m.

Further, in Comparative Example 2, the twisting pitch different from that of the embodiment was adopted and the propagation delay time difference could be suppressed to be as small as that of the embodiment, but regarding the crosstalk characteristic, the twisted pair was connected midway. It was found that the working example was superior. From this, it can be understood that if the signal transmission path is configured with one multi-pair cable, there is a limit to the compatibility between reduction of the propagation delay time difference and good crosstalk characteristics.

In the above embodiment, the twisted wires are connected to each other through known socket connectors and pin connectors (not shown) provided at both cut ends of the multi-pair cable.
The connector used is a socket connector of 17JE-1.
3250-02 (D2A) (Daiichi Denshi Kogyo KK), pin connector is 17JE-23250-02 (D8A)
(Daiichi Denshi Kogyo Co., Ltd.). Solder each twisted pair of cuts of the multi-pair cable to the socket and pin connectors to connect the pair to be interrupted. Soldering,
Both connectors, which had been assembled with the shell (cover), were fitted to each other to connect all the twisted pair wires to form a multi-pair cable signal transmission path.

In the above embodiment, the connected multi-pair cable is a multi-pair cable having the same specifications. However, even if the connected multi-pair cables are different multi-pair cables, the crosstalk characteristics are not deteriorated. It was found that the difference in propagation delay time was improved.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

[Table 5]

[0035]

[Table 6]

[0036]

[Table 7]

[0037]

As described above, the multi-pair cable signal transmission line of the present invention maintains good crosstalk characteristics because the twisting rates of the adjacent twisted pairs are different. In addition, since two or more multi-pair cables are connected and the twisted pair wires are connected so that the propagation delay time of the paired twisted wire after connection is the same as much as possible over the entire signal transmission path, The propagation delay time difference can be kept extremely small.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a multi-pair cable used in a multi-pair cable signal transmission line of the present invention.

FIG. 2 is a perspective view showing an example of twisted pair wires of the multi-pair cable of FIG.

[Explanation of symbols]

A multi-pair cable a pair stranded wire b multi-pair stranded wire c buffer layer d ₁ and d ₂ shield layer e sheath f conductor g insulation coating h insulation strand

Claims (3)

[Claims] 1. A multi-pair cable signal transmission line in which at least two multi-pair cables in which a plurality of twisted pair wires are collectively twisted are connected to each other, wherein the plurality of twisted pair wires have different twist rates. Are arranged so that they are adjacent to each other, and the connection between the twisted pair wires is based on the propagation delay time value per unit length of each twisted pair wire before connection, which is measured in advance. A multi-pair cable signal transmission line characterized in that propagation delay time values are made as uniform as possible over the entire length of the signal transmission line. 2. The multi-pair cable signal transmission line according to claim 1, wherein two multi-pair cables are connected at a substantially central portion of the entire length of the signal transmission line. 3. The multi-pair cable is connected to each other via a connector.
The described multi-pair cable signal transmission line.