JP2003297154A - Transmission cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an intrusion of a drain wire to twist pair cables by reducing an external skew of the pair cables by managing an equal length of the pair cables. <P>SOLUTION: A transmission cable 1 comprises: a plurality of signal wires 3. The wires 3 are obtained by batch coating fixing with the same sheathing resin 5 by extrusion molding, for example, a pair of signal wires 3. Thus, the equal length of the pair of the wires 3 is surely managed, and hence an internal skew and a skew between the pair are reduced. Since the pair of the wires 3 are batch coating fixed with the sheathing resin 5, the intrusion for imparting an influence of the drain wire 9 to the wires 3 is reduced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission cable, and more particularly to a differential signal transmission cable for high-speed data transmission used for internal wiring of various communication devices and large equipment such as computers.

[0002]

2. Description of the Related Art Referring to FIG. 6, in a conventional transmission cable 101 for high speed data transmission, two-core signal lines 103 are separately sheathed with resin 105 as an insulating material and extruded. A drain cable 111 is attached to a pair cable 109 composed of a core insulated wire 107, which is tape-wound with a conductive tape 113 such as an aluminum tape and shielded. + To this 2-core pair cable 109
A differential voltage signal is sent by applying the potentials of − and −.

[0003]

By the way, in the conventional transmission cable 101 for high-speed data transmission, the drain wire 111 is cut into between the insulated wires 107, which may affect the characteristic impedance. That is, when a differential voltage signal is sent by applying + and-potentials to the pair cable 109, the transmission signal speed of the pair cable 109 is different, and as a result of this, the skew within the pair ( Inward propagation delay time difference)
There is a problem that skew between pairs (difference in propagation delay time between pairs) occurs. There is also an effect on crosstalk. Moreover, in the transmission cable 101 having the structure shown in FIG. 6, it is difficult to avoid the influence of the bite by the drain wire 111.

The difference in transmission speed is largely due to the difference in the length of the two-core pair cable 109. For example, a difference of 1 mm occurs when the length of the cable 109 is 1.5 m. This is because the two-core insulating wires 107 extruded as the insulating sheath of the signal wire 103 are arranged in parallel, and the tension applied to each insulating wire 107 when applying a tension to each insulating wire 107 and winding the tape. Since it is impossible to make uniform, it is difficult to manage isometric length.

In order to prevent the above-mentioned drain wire 111 from biting, the drain wire 111 is connected to the two-core pair cable 1
If it is moved away from 09, the ground plane cannot be taken uniformly, which affects crosstalk and the like.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to perform equal-length management of pair cables in order to reduce skew inside and outside the pair cables,
It is an object of the present invention to provide a transmission cable that can reduce the influence on the characteristic impedance by reducing the bite of the pair cable of the drain wire into the resin.

[0007]

In order to achieve the above object, a transmission cable of the present invention according to claim 1 is provided with a plurality of signal lines collectively covered with the same insulating resin and arranged outside the resin. And a drain tape and a conductive tape that covers the drain wire and the resin.

Therefore, the equal length management of the plurality of signal lines is surely performed by collectively extruding the plurality of signal lines, so that the skew between pairs and the skew between pairs are reduced.

A transmission cable according to a second aspect of the present invention is the transmission cable according to the first aspect, wherein a groove portion for arranging a drain line is provided on the resin surface, the groove portion being located between a pair of signal lines. It is characterized by.

Therefore, since the drain wire is embedded in the groove and wound around the tape with the conductive tape, the movement of the drain wire is reduced, and thus the bite which the drain wire gives to the signal line is suppressed. Further, since the position of the drain wire is determined by the groove portion, the ground surface is made uniform, so that the transmission characteristic is also improved.

A transmission cable according to a third aspect of the present invention is the transmission cable according to the second aspect, wherein the depth of the groove and the width of the opening are larger than the diameter of the drain wire.

Therefore, since the depth of the groove and the width of the opening are larger than the diameter of the drain wire, the bite of the drain wire into the sheath resin, which is given to the signal wire, is further reduced, so that the specific impedance can be secured. Becomes Further, since the movement of the drain line is further reduced, the ground plane is always secured uniformly.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Referring to FIGS. 1 to 3, a transmission cable 1 according to this embodiment has a pair of signal lines 3 which are substantially parallel to each other, and is covered with an identical insulating sheath resin 5 by extrusion molding. A fixed and two-core pair cable 7 is configured. By thus extruding the pair of signal lines 3 together, the equal length management of the two-core pair cable 7 is surely performed, so that the in-pair skew and the inter-pair skew are reduced.

Further, a drain wire 9 is provided on the pair cable 7 along the surface of the sheath resin 5 so as to be located between the pair of signal wires 3, and the outside of the drain wire 9 and the pair cable 7 is provided. Is wound with a conductive tape 11 such as an aluminum tape and shielded.

The outer shape of the sheath resin 5 of the pair cable 7 may be variously changed as shown in FIG. 1 to FIG. 3, and may be a shape other than the shape shown in FIG. 1 to FIG. It doesn't matter.

In the transmission cable 1 of the embodiment shown in FIG. 1, a groove portion 13 for arranging a drain wire is provided on the surface of the sheath resin 5 of the pair cable 7 between the pair of signal wires 3. Although two groove portions 13 are provided in FIG. 1, at least one groove portion 13 may be provided.

The reason for providing the groove 13 is to prevent the drain wire 9 from moving within the transmission cable 1 in order to prevent the drain wire 9 from biting into the sheath resin 5 which may affect the signal wire 3. Need to Therefore, the drain wire 9 is embedded in the groove portion 13 and wound by the conductive tape 11 to reduce the movement of the drain wire 9. Further, since the position of the drain wire 9 is determined in the groove portion 13, the ground (GND) surface is made uniform, so that the transmission characteristic is also improved.

In the embodiment of FIG. 1, the depth B and the opening spread width C of the groove 13 are formed larger than the diameter A of the drain line 9. This allows the drain wire 9
Since there is little biting into the sheath resin 5 that affects the signal line 3, it is possible to secure a specific impedance. Further, since the movement of the drain wire 9 within the shield of the conductive tape 11 is further reduced, the ground surface is always ensured to be uniform.

Next, the manufacturing process of the transmission cable 1 of this embodiment will be described.

Referring to FIGS. 4 and 5, an extrusion molding machine 15 for molding the transmission cable 1 is illustrated, and the thermoplastic resin as the common sheath resin 5 of the pair of signal lines 3 is the extrusion molding machine. For example, extrusion coating is performed collectively in an extrusion head 17 as an extrusion die of 15, and a pair of signal lines 3 are simultaneously and integrally fixed by a sheath resin 5.

As shown in FIG. 5, the structure of the inside of the extrusion head 17 of the extrusion molding machine 15 is such that the die 19 for extruding the thermoplastic resin has a cross-sectional shape in consideration of resin shrinkage. The outer shape of the sheath resin 5 is substantially the same as that of the sheath resin 5, and a nipple 21 for passing the pair of signal lines 3 is provided at a predetermined position in the die 19. That is, the pair of signal lines 3 is connected to the nipple 2
The thermoplastic resin which has been sent so as to pass through the inside of the die 19 through the inside of the die 19 flows in the flow path between the nipple 21 and the die 19 and simultaneously passes the pair of signal lines 3 from the tip of the die 19 to The pair cable 7 is extruded with the coating fixed.

Then, the above-mentioned cooled paired cable 7
The drain wire 9 is attached to the surface of the sheath resin 5. Particularly, in the transmission cable 1 of FIG. 1, the drain wire 9 is sent out so as to be embedded in the groove portion 13 of the pair cable 7.
The drain wire 9 and the pair cable 7 are tape winding devices 2
3, the tape is wound from the outside with a conductive tape 11 such as an aluminum tape, shielded, and then wound.

As described above, in the transmission cable 1 according to the embodiment of the present invention, the pair of signal lines 3 are extruded together by the sheath resin 5 to ensure uniform length management of the pair of signal lines 3. Is performed, and the skew between pairs and the skew between pairs can be reduced. Particularly in the transmission cable 1 in which the groove portion 13 for disposing the drain wire is provided on the surface of the sheath resin 5, the movement of the drain wire 9 embedded in the groove portion 13 is reduced, so that the biting of the drain wire 9 is suppressed. . Further, since the drain wire 9 is positioned in the groove portion 13, the ground surface is made uniform and the transmission characteristics are improved. In particular, the depth B of the groove 13
And the width C of the opening is made larger than the diameter A of the drain line 9, so that the effect of the above point is further enhanced.

The present invention is not limited to the above-described embodiment, but can be implemented in other modes by making appropriate changes. In this embodiment, the transmission cable in which the pair of signal lines 3 are collectively covered and fixed with the sheath resin 5 has been described as an example. It doesn't matter.

[0026]

As can be understood from the description of the embodiment of the invention as described above, according to the invention of claim 1, a plurality of signal lines are extruded at one time, so that the plurality of signal lines have the same length. The management can be performed surely, and the skew between pairs and the skew between pairs can be reduced.

According to the second aspect of the present invention, since the groove portion is provided on the surface of the resin, the drain wire is embedded in the groove portion and the tape is wound with the conductive tape. Can be suppressed. Further, since the position of the drain wire is determined by the groove portion, the ground surface can be made uniform, so that the transmission characteristics can be improved.

According to the invention of claim 3, since the depth of the groove and the width of the opening are made larger than the diameter of the drain wire,
The bite of the drain wire into the sheath resin can be further reduced, and the specific impedance can be secured. Further, since the movement of the drain line can be further reduced, the ground plane can be always ensured uniformly.

[Brief description of drawings]

FIG. 1 is a sectional view of a transmission cable according to an embodiment of the present invention.

FIG. 2 is a sectional view of a transmission cable according to another embodiment of the present invention.

FIG. 3 is a sectional view of a transmission cable according to another embodiment of the present invention.

FIG. 4 is a schematic explanatory view showing a manufacturing process of the transmission cable according to the embodiment of the present invention.

5 is a partial cross-sectional view within the extrusion head of the extruder of FIG.

FIG. 6 is a cross-sectional view of a conventional transmission cable.

[Explanation of symbols]

1 transmission cable 3 signal lines 5 sheath resin 7 pair cable 9 drain wire 11 Conductive tape 13 Groove (for disposing drain wire) 15 Extruder

Claims (3)

[Claims] 1. A plurality of signal lines collectively covered with the same insulating resin, a drain line disposed outside the resin, and a conductive tape covering the drain line and the resin. A transmission cable characterized in that 2. The transmission cable according to claim 1, wherein the resin surface is provided with at least one groove for arranging a drain line, the groove being located between the pair of signal lines. 3. The depth of the groove and the width of spread of the opening are larger than the diameter of the drain line.
The listed transmission cable.