JP2010033879A - Multi-core round composite cable for low skew differential transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome the defects wherein a paired and twisted structure in the prior art is harder to stabilize in the longitudinal direction than a coaxial structure and liable to increase pair-to-pair skew, and a larger-diameter power cable is required for securing the high speed signal transfer characteristics of power wires and increasing the current capacity of the power wires. <P>SOLUTION: In a high speed interface cable consisting of signal wires and the power wires for high frequency transfer, a center inclusion is applied into a sheath, the paired coaxial signal wires of at least four cores as even-number cores are arranged therearound at almost the same distance from a central part of the center inclusion, namely, in the same layer in view from the cross section of the cable, and a +Vcc line of one or more thin insulating power wires subjected to insulating coating is inserted into a gap between the plurality of coaxial signal wires so that it is applied to a coaxial GND line of the coaxial signal wires instead of a power supply GND line of the thin insulating power wires. Thus, a low skew differential transmission multi-core round type complex cable has less pair-to-pair skew and a thinner shape. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention is mainly used for a camera link cable or the like corresponding to high-speed image transmission, and in particular, not only can the distance be extended by improving the propagation delay time difference (hereinafter referred to as skew) performance between pairs, but also the impedance of the power supply line can be reduced. The present invention relates to a multi-core round composite cable for low skew differential transmission, which has improved noise resistance performance by reduction.

  Currently, in order to cope with high-speed image transmission, strict performance has been required for cable distance extension and transmission signal performance with high-speed and noise-resistant measures. On the other hand, the size of the connector is becoming smaller. In this way, a space in which the power supply line can be accommodated within the outer diameter defined by the applicable connector is determined.

  First, in the case of Japanese Patent Application Laid-Open No. 2004-146354 (Patent Document 1), the plurality of signal lines are round cables, but are twisted pairs, and without adding ground lines or power lines, Although it is described that impedance control and skew control are performed by arranging adjacent to the shield, it is described that it must be disposed adjacent to the shield.

  In the case of Japanese Patent Laid-Open No. 2003-338224 (Patent Document 2), a flat structure for preventing deterioration of skew is described.

  Next, Japanese Patent Laid-Open No. 2002-358841 (Patent Document 3) describes a structure in which the inward skew is reduced.

JP 2004-146354 A JP 2003-338224 A JP 2002-358841 A

  Thus, in the case of the conventional patent document 1, although it is a round cable, it must be arrange | positioned adjacent to a jacket shield with a twisted pair, and the skew deterioration by a pair cannot be avoided. Thus, as shown in FIG. 2, the structure of the conventional pair is more stable in the cable longitudinal direction of the signal pair 1 and the signal pair 2 from the cable center than the coaxial type structure of the present invention. Due to the difficult structure, there is a drawback that the skew between the pairs tends to increase. Moreover, since patent document 2 is a flat structure, it receives a restriction | limiting in an application and is not a round structure like this invention. Furthermore, Patent Document 3 describes a structure in which the inward skew is reduced, but it is not intended to reduce the inward skew as in the present invention. Further, the power supply line of the conventional round composite cable 1 ′ is composed of two lines, that is, the + Vcc line of the insulated power supply line and the GND line of the insulated power supply line. Therefore, in order to ensure the characteristics (attenuation amount deterioration, phase distortion, characteristic impedance variation, skew variation, DC resistance value, etc.) in high-speed signal transmission, which is the biggest drawback of conventional cables, and increase the current capacity of the power line There was also the fault that the cable would be thick.

The present invention has been intensively studied to solve these problems. As a result, low skew differential transmission using a coaxial signal line in which the skew is stable instead of a twisted pair for the purpose of improving the paired skew. Multi-core round composite cable for
Embodiment 1 of the present invention is a high-speed interface cable composed of a signal line and a power line for high-frequency transmission, and a coaxial signal line in which a center is provided in the sheath and a pair is formed with an even number of four or more cores around it. One or a plurality of thin-diameter insulations arranged so as to be at substantially the same distance, that is, in the same layer from the central portion of the central interposition as viewed from the cable cross section, and insulatively coated in the gaps between the plurality of coaxial signal lines By inserting the + Vcc line of the power supply line and applying it to the coaxial GND line of the coaxial signal line without providing a separate power supply GND line of the thin-diameter insulated power supply line, the skew is reduced by reducing the skew between the pair and reducing the diameter. This is a multi-core round composite cable for differential transmission. In the second embodiment, the first plurality of coaxial signal lines are made the same color in order to make the cost merit and the skew between the pairs constant, By the different colors of the insulation thin insulated power line + Vcc line consisting of a low-skew differential transmission multi-core round composite cable that allows identification of the coaxial signal line at the time of connection.

As is clear from the above description, according to the multi-core round composite cable for low skew differential transmission of the present invention,
1. The distance can be extended by improving the skew performance between pairs.
2. By arranging the small-diameter insulated power supply lines in the gap, the impedance can be lowered, so that the noise resistance of the power supply line and the influence of noise from the power supply line to the signal line can be greatly reduced.
3. Since it is possible to increase the number of power line cores in a gap, the power supply power required for a camera or the like can be improved.
4). By inserting the + Vcc line of multiple insulated power supply lines into the gap between the coaxial signal lines and not providing the power supply GND line that has been conventionally inserted, a coaxial signal line shield (coaxial GND line) is applied. Diameter reduction is obtained.
5). By using different color insulators for the power line, the coaxial signal line can be easily identified at the time of connection.
6). It is possible to fit within the outer diameter of the mating connector.
7). In the case of the conventional TP (twisted pair) type, when the terminal processing is performed on the connector, it is necessary to return more, so the exposed length of the terminal processing becomes large and reflection occurs. Since the coaxial line of the invention is a two-core parallel pair, connector processing can be performed without returning it, so that the stripping of terminal processing is small, and its length is short, so reflection is small and high-speed transmission is possible Become.
Therefore, its industrial value is great.

  Hereinafter, an embodiment of a multi-core round composite cable 1 for low skew differential transmission according to the present invention will be described in detail with reference to the accompanying drawings.

  First, in the present invention, as shown in FIG. 1, a central interposition 8 is provided in a sheath 10 and a coaxial signal line 5 in which a pair of four or more cores are formed around the central interposition is viewed from the cross section of the cable. + Vcc line of one or a plurality of small-diameter insulated power supply lines 7 arranged so as to be substantially the same distance from the central portion of the signal line, that is, in the same layer, and insulated in a gap between the plurality of coaxial signal lines By inserting the cable and applying it to the coaxial signal line shield (coaxial GND line) of the coaxial signal line without providing the power supply GND line of the small-diameter insulated power supply line that has been conventionally inserted, the pair has a low skew and a small diameter. This is a multi-core round composite cable for differential transmission with low skew. Here, the coaxial signal line 5 of the present invention is made into a two-core parallel pair to form 6A of the signal pair 1, 6B of the signal pair 2, 6C of the signal pair 3, 6D of the signal pair 4, and 6E of the signal pair 5. did. The coaxial signal wire 5 of the present invention was a tin-plated annealed copper wire of 0.127 mm and more than 7 conductors. Furthermore, as an example of the insulation coating of the thin-diameter insulated power supply line, other insulation coating such as tape or coating or extrusion coating is meant. Next, as a first point of the present invention, as a countermeasure against skew, a coaxial signal line whose skew is more stable than the signal line is used as a pair, and almost the same distance from the central portion of the interposition viewed from the cable cross section, that is, Arrange them to be in the same layer. With such an arrangement, the differential transmission signal lines have substantially the same line length difference as viewed from the longitudinal direction of the cable, and as a result, the delay times viewed from the line length difference are the same. Thus, in order to reduce the propagation delay time difference, it is necessary to reduce the line length difference. FIG. 1 shows the present invention when there are 10 coaxial signal lines and 5 signal pairs, and FIG. 2 shows the present invention when there are 4 coaxial signal lines and 2 signal pairs. Not limited to this, as long as it is an even number of four or more cores, it does not matter. Next, as a second point, with respect to the power supply line, a + Vcc line of a plurality of thin-diameter insulated power supply lines 7 with insulation coating is inserted into a gap between the plurality of coaxial signal lines, and the conventional power supply line is inserted. It is possible to reduce the diameter by applying to the coaxial signal line shield (coaxial GND line) of the coaxial signal line without providing the power supply GND line of the thin-diameter insulated power supply line. The small-diameter insulated power supply line can be reduced in impedance by being surrounded by a coaxial signal line shield (coaxial GND line) used for a differential transmission signal line, and noise resistance can be improved. It becomes possible. As described above, the present invention is a cable having a coaxial structure instead of a pair structure, and further increasing the space factor, taking into consideration the noise effect from the power line and the stability (characteristic impedance, etc.) at high frequencies. A core structure was adopted. Next, the small-diameter insulated power supply line can improve the current capacity by increasing the number of cores in the gap (the amount of electricity flowing can be increased). Not only can the power supplied be improved, but the power line conductor can be divided to save space and achieve compactness. The configuration table of the multi-core round composite cable 1 for low skew differential transmission according to the present invention is shown in Table 1 below.

  Next, in the second embodiment of the present invention, as shown in FIG. 1, a plurality of coaxial signal lines of the first embodiment are made the same color in order to keep the cost merit and the skew between the pairs constant. This is a low skew differential transmission multi-core round composite cable that makes it easy to identify the coaxial signal line at the time of connection by making the insulator of the + Vcc line of the small-diameter insulated power supply line different in color. Here, a low speed control signal line may be used as the + Vcc line of the thin-diameter insulated power supply line.

  A comparative study was carried out on the skew between pairs of multi-core round composite cables for low skew differential transmission of the present invention and conventional multi-core round composite cables. As shown in Table 2, the average skew value of the multi-core round composite cable for low skew differential transmission of the present invention is 8.0 ps / m, whereas the skew value of the conventional product is Was found to be 36.1 ps / m, a better result than that of the conventional product.

  Table 3 shows the results of a comparative study on the power line impedance (conductor resistance) of the multi-core round composite cable for low skew differential transmission of the product of the present invention and the conventional multi-core round composite cable. Shown in The multi-core round composite cable for low skew differential transmission of the present invention product was found to show better results than the conventional round composite cable.

  In the case of the present invention, as a representative cable structure, for example, in the case of a coaxial signal line, outer peripheral shield 1, 2, 10 cores and 4 cores, the intervention has been described as a round shape, but the main point is from the central part of the center intervention. Needless to say, it may be arranged so as to have substantially the same distance, that is, in the same layer, and includes various deformations regardless of the presence or absence of interposition.

  The multi-core round composite cable for low skew differential transmission of the present invention can be widely applied to LVDS (low voltage differential signal) other than the camera link cable compatible with high-speed image transmission.

1 is a structural cross-sectional view of a multicore round composite cable 1 for low skew differential transmission of the present invention. It is comparison explanatory drawing about the skew between the pair of the multi-core round composite cable 1 for low skew differential transmission of this invention and the conventional round composite cable 1 '.

Explanation of symbols

1 Example of multi-core round composite cable for low skew differential transmission of the present invention 2 Conductor 3 Insulator 4 Coaxial signal line shield (coaxial GND line)
5 Coaxial signal line 6A Signal pair 1
6B Signal pair 2
6C signal pair 3
6D signal pair 4
6E signal pair 5
7 + Vcc line of thin insulated power supply line 8 Intervening 9A Outer shield 1
9B Outer shield 2
10 Sheath 1 'Example of conventional round composite cable 2' Conductor 3 'Insulator 4' Signal line shield 6A 'Signal pair 1
6B 'signal pair 2
7 '+ Vcc line of insulated power supply line 7 "GND line of insulated power supply line
10 ′ sheath
11 'twisted signal wire

Claims (2)

In a high-speed interface cable consisting of high-frequency transmission signal lines and power supply lines, a central interposition is provided in the sheath, and coaxial signal lines formed with pairs of even numbers of four or more cores around the center are located in the center of the central interposition as viewed from the cable cross section. Insert the + Vcc line of one or more small-diameter insulated power lines that are arranged so that they are almost the same distance from the section, that is, in the same layer, and that are insulated and coated in the gaps between the plurality of coaxial signal lines. The low skew differential transmission is characterized by reducing the skew between the pair and reducing the diameter by applying it to the coaxial GND line of the coaxial signal line without providing a power supply GND line of the thin-diameter insulated power supply line. Multi-core round composite cable. The plurality of coaxial signal lines according to claim 1 are made the same color in order to keep the cost merit and the inter-pair skew constant, and the insulators of the + Vcc line of the plurality of thin insulated power supply lines are made different colors. The multi-core round composite cable for low skew differential transmission according to claim 1, wherein the coaxial signal line can be easily identified at the time of connection.

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