DATA CABLE, DATA TRANSMISSION METHOD, AND METHOD FOR PRODUCING A DATA CABLE

Abstract

A data cable, which is particularly suitable for the automotive industry, is cost-effective to produce and allows high transmission frequencies into the gigahertz range. The data cable has two wire pairs which each have two wires which are surrounded by a pair shield. In addition to the pair shield, a planar or flat shielding element which does not surround the core pairs and makes contact with the two pair shields is arranged between the wires. The shielding element has, in particular, individual wires which run next to one another. Contact can advantageously be made with the pair shield in a plug region in a simple manner by way of the shielding element.

Claims

1. A data cable, comprising: two wire pairs each including two wires; a pair shielding surrounding each of said two wire pairs; a planar shielding element disposed between said wire pairs and not encompassing said wire pairs, said planar shielding element making contact with each said pair shielding.

2. The data cable according to claim 1, wherein said planar shielding element is formed of a plurality of single individual wires extending adjacent to one another.

3. The data cable according to claim 2, wherein said individual wires are a splayed-out stranded conductor.

4. The data cable according to claim 1, wherein said planar shielding element comprises a shielding foil.

5. The data cable according to claim 4, wherein said shielding foil comprises a ferro-magnetic material.

6. The data cable according to claim 4, wherein said shielding foil is a nickel foil or a coated carrier foil provided with a layer of powder particles.

7. The data cable according to claim 1, wherein said two wire pairs together with said shielding element form a stranded bundle.

8. The data cable according to claim 1, wherein said wire pairs contain wires that are not twisted wires.

9. The data cable according to claim 1, wherein said pair shielding is formed of a longitudinally extending pair foil.

10. The data cable according to claim 1, wherein each respective wire pair is a one piece construction with said two wires surrounded by a common wire insulation.

11. A method of transmitting signals, the method comprising: providing a data cable according to claim 1; and transmitting signals in the form of a differential data signal in a respective wire pair.

12. The method according to claim 11, which comprises transmitting the signals at a data rate greater than one gigahertz.

13. The method according to claim 12, which comprises transmitting the signals at a data rate greater than 5 GHz.

14. A method for producing a data cable, the method comprising: providing two shielded wire pairs each having two wire pairs and a respective pair shielding; and inserting a planar shielding element that does not surround the wire pairs between the two shielded wire pairs.

15. The method according to claim 14, which comprises forming the data cable according to claim 1.

16. The method according to claim 14, which comprises forming the data cable in a continuous process, and wherein the planar shielding element comprises a stranded conductor that is splayed-out and extends parallel with the wire pairs.

17. The method according to claim 14, which comprises forming the data cable in a continuous process, and wherein the planar shielding element is a shielding foil that extends parallel with the wire pairs.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0043] FIG. 1 is an end view of a section through a data cable;

[0044] FIG. 2 is a section taken through a first embodiment of a shielding element;

[0045] FIG. 3 is a section taken through a second embodiment of the shielding element;

[0046] FIG. 4 is a section taken through a third embodiment of the shielding element;

[0047] FIG. 5 is a section showing a wire pair that is surrounded by a longitudinally-folded pair foil; and

[0048] FIG. 6 illustrates a schematic comparative view of the progression of the ACR ratio with respect to the transmission frequency for a conventional star-quad and for a data cable in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0049] Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a data cable 2 which comprises and is in particular finally formed by means of two shielded wire pairs 4, or core pairs 4, that are surrounded in each case by a pair shielding 6. A further shielding element 8 is arranged between the wire pairs 4. This shielding element is arranged in a separating plane between the two wire pairs 4 and is clamped between said pairs. The shielding element 8 extends parallel within this separating plane and in particular over the entire length (when viewed in the cross-section) of a respective wire pair 4. The shielding element therefore comprises a length of approximately double the diameter of a respective wire 14.

[0050] The wire pairs 4 together with the shielding element 8 form a stranded bundle 10, in other words they are twisted with one another in the longitudinal direction of the data cable 2. This entire stranded bundle 10 is finally surrounded by an outer cable sheath 12 that is embodied from a suitable insulating material.

[0051] A respective wire pair 4 comprises two wires 14 that are formed in each case from a central conductor 16 and a wire insulation 18. A suitable insulating material that is suitable for transmitting high frequency data signals is selected for the wire insulation 18. The entire data cable 2 typically comprises an outer diameter D that lies in the range of a few millimeters, by way of example in the range between 4 and 8 mm.

[0052] Fundamentally, it is also possible to combine multiple data constructions of this type, as are illustrated in FIG. 1, to form one complete cable. It is also possible to integrate a plurality of the described cable bundles, in other words without the outer cable sheath 12, into a complete cable construction. In so doing, it is however of advantage if the respective cable bundle 10 is still surrounded by a shielding arrangement.

[0053] However, the cable construction finally illustrated in FIG. 1 is preferred for the data cable 2. A suitable plug connector, in particular a so-called HSD plug connector, is usually arranged at one end of the illustrated data cable 2 and in particular at both ends. A plug connector of this type comprises 4 contacts by way of which the individual wires 14 are contacted and in addition a ground contact, and the shielding element 8 makes contact with said ground contact. Conventional types of plug connectors as are used currently in the automotive industry in combination with star-quads can fundamentally still be used.

[0054] The shielding element 8 is embodied—as is evident in FIG. 2—in a preferred first variant from a multiplicity of individual wires 20. The individual wires are in particular copper wires. In order to produce the shielding element 8, a conventional copper stranded wire or any other conductor bundle is used in an expedient manner, wherein the single individual wires 20 are splayed out so that the planar shielding element 8 as illustrated in the cross-section in FIG. 2 is formed. The individual wires 20 are arranged in a few layers extending adjacent to one another. Said individual wires therefore form in this respect a wire bundle that has been somewhat pressed flat. This bundle can be contacted in a particularly simple manner at one end on the plug connector by the ground contact. For this purpose, the individual wires 20 are brought back together and contacted.

[0055] In accordance with a second embodiment illustrated in FIG. 3, this wire bundle comprising the individual wires 20 is supplemented by a shielding foil 22 that comprises in particular a magnetic shielding effect. The shielding foil 22 is formed for this purpose from a material that has a magnetic shielding effect, in particular from a ferro-magnetic material. It is preferred that the shielding foil 22 is a metal foil, by way of example a nickel foil or an iron foil.

[0056] As an alternative to this metal foil, the shielding foil 22 in accordance with FIG. 4 is embodied in a multi-layer manner and comprises a carrier foil 24 having a coating 26 that is applied thereto. The coating 26 can be a vapor-deposited suitable layer of a ferro-magnetic material or also a layer of powder particles of a suitable material. In particular, said material is an electrically conductive material so that it is ensured by way of the coating that an electrically conductive contact is also made with the individual wires 20 and the two pair shieldings 6. The carrier foil 24 can be provided on both faces with the coating 26. As alternative thereto, said carrier foil is only provided on one face with the coating 26, as is illustrated in FIG. 4. In this case, the carrier foil 24 is folded in particular once in the longitudinal direction so that the electrically conductive coating 26 is on both outer faces.

[0057] Finally, the illustration in accordance with FIG. 5 once again shows the construction of the shielded wire pair 4. It is particularly evident that the pair shielding 6 is formed by means of a longitudinally-folded pair foil 28. Said pair foil is laid around the two wires 14 and comprises an overlap that extends parallel with the wires 14. The pair foil 28 is usually a metallized synthetic material carrier foil. The metallized face is preferably facing outwards.

[0058] The data cable 2 described in this case is made available in particular as a cable that is pre-assembled with a plug connector and used in the automotive industry. It is thus installed in the final state in the motor vehicle. It is suitable for transmitting data signals up to in the GHz range. In particular, the LVDS standard (low voltage differential signaling) is used for data transmission in particular in the automotive industry.

[0059] Overall, this data cable 2 is comparatively cost-effective to produce. In comparison to conventional star-quads, the production process is simplified as a result of using the pair shielding 6 since fewer demands are placed on precisely positioning the single wires 14 in a highly precise manner with respect to each other. The production process is also more cost-effective in comparison to conventional high speed data cables that are provided with a spun pair shielding since in the present case a longitudinally-folded pair foil 28 is used. A further particular advantage is produced by virtue of the fact that an outer shield is omitted, as a consequence of which overall in comparison to conventional data cables the amount of copper required is less and thus the costs are reduced. Simultaneously, this also produces a reduction in weight which is important for the automotive industry. Finally, by virtue of the cable construction, the amount of space required is identical to that in the case of a star-quad, as is nowadays already usual in the automotive industry. The data cable 2 can therefore be used as a replacement for star-quad constructions previously used.

[0060] Higher data rates in comparison to a star-quad arrangement and connection can be achieved using the data cable 2 described here. This is explained with reference to FIG. 6. This is demonstrated by the progression of the ACR ratio of attenuation to interference (in particular caused by near-end crosstalk) with respect to the frequency f of the data signal. The broken line indicates the progression in the case of a star-quad arrangement and the uninterrupted line indicates the progression in the case of a data cable 2 in accordance with the invention. As is evident in the illustration, although the ACR ratio in the case of low frequencies is greater in the case of the star-quad, the ratio greatly reduces in the case of higher frequencies in the GHz range. In contrast, the ACR ratio in the case of the data cable 2 in accordance with the invention over a large frequency range also in the GHz range up to in the range of approx. 10 GHz is sufficiently high for a reliable signal transmission. The lower line extending in a transverse manner represents a limit value for a reliable signal transmission. This limit is by way of example 5 to 10.

[0061] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:

[0062] 2 Data cable

[0063] 4 Wire pair

[0064] 6 Pair shielding

[0065] 8 Shielding element

[0066] 10 Stranded bundle

[0067] 12 Cable sheath

[0068] 14 Wire

[0069] 16 Conductor

[0070] 18 Wire insulation

[0071] 20 Individual wires

[0072] 22 Shielding foil

[0073] 24 Carrier foil

[0074] 26 Coating

[0075] 28 Pair foil