US20120312579A1 - Cable jacket with embedded shield and method for making the same - Google Patents

Abstract

A cable jacket that comprises first and second jacket layers each formed of a jacket material. At least one shielding tape is embedded between the first and second jacket layers. The shielding tape is formed of a substrate material and the substrate material has at least one conductive segment.

Description

FIELD OF THE INVENTION
• The present invention relates to a jacket for a cable that includes an embedded shield and the method for making the jacket. More specifically, the jacket includes a shield that is a shielding tape with discontinuous conductive shielding segments. The shielding tape is embedded with the jacket by co-extruding the shielding tape with the jacket.
BACKGROUND OF THE INVENTION
• Conventional communications cables typically include a core of twisted pairs of insulated conductors that are enclosed in a protective jacket. To avoid crosstalk with other cables, often referred to as alien crosstalk, conventional cables often include at least one shielding layer disposed around the core of twisted pairs of conductors. A non-conductive barrier layer between the shielding layer and the pairs must also be provided to insulate the core of pairs of the cable.
• Such cables, however, are often bulky because of the requirement of both a shielding layer and a barrier layer. Therefore, a need exists for a cable that protects against alien crosstalk and that is not bulky.
SUMMARY OF THE INVENTION
• Accordingly, the present invention may provide a cable jacket that comprises first and second jacket layers each formed of a jacket material. At least one shielding tape may be embedded between the first and second jacket layers. The shielding tape is formed of a substrate material and the substrate material has at least one conductive segment. In a preferred embodiment, the substrate material and the jacket material are the same, although different materials may be utilized. In another embodiment, the substrate material includes a plurality of conductive segments disposed in a spaced discontinuous arrangement. In yet another embodiment, a plurality of shielding tapes are embedded between the first and second jacket layers.
• The present invention may also provide a cable that comprises at least one twisted pair of insulated conductors and a jacket that encloses the twisted pair of insulated conductors. The jacket is formed of a jacket material. A shielding tape may be embedded in the jacket. The shielding tape is formed of a substrate material that has at least one conductive segment. The cable does not include a barrier layer.
• The present invention may further provide a cable assembly that comprises a plurality of cables that are bundled together. Each of the plurality of cables includes at least one twisted pair of insulated conductors, a jacket enclosing the at least one twisted pair of insulated conductors where the jacket is formed of a jacket material, and at least one shielding tape embedded in the jacket. The at least one shielding tape is formed of a substrate material and the substrate material has at least one conductive segment, whereby the cable does not include a barrier layer enclosed by the jacket.
• The present invention may also provide a method for making a cable jacket that comprises the steps of providing at least one shielding tape that has a substrate formed of a substrate material where the substrate includes at least one conductive segment; inserting the at least one shielding tape between first and second jacket layers of the cable jacket and each of the layers is formed of a jacket material; and co-extruding the shielding tape with the first and second jacket layers, wherein the substrate material of the shielding tape and the jacket material of the first and second jacket layers are the same such that during the co-extrusion step, the substrate and the first and second jacket layers bond together.
• Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
• A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
• FIG. 1 is a cross-sectional view of a cable having a jacket according to an exemplary embodiment of the invention, showing the jacket with a plurality of shields embedded therein;
• FIG. 2 is a plan view of a shield of the cable jacket illustrated inFIG. 1, showing the shield as a tape with a plurality of conductive segments; and
• FIG. 3 is a cross-sectional view of a cable assembly according to an embodiment of the invention, showing a plurality of the cables bundled together.
DETAILED DESCRIPTION OF THE INVENTION
• Referring toFIGS. 1 and 2, ajacket100 for a cable C, such as a communications cable, according to an exemplary embodiment of the present invention minimizes noise coming from external cable sources, i.e. alien crosstalk, without the need for grounding the cable C. Thejacket100 of the present invention accomplishes the above by combining at least onediscontinuous shield200 with the jacket material.
• As seen inFIG. 1, the cable C includes thejacket100, one or more twisted pairs ofinsulated conductors102, and anoptional separator104 disposed between thepairs102 to isolate the same. Thejacket100 includes inner andouter layers110 and120 that, when combined with one or more of theshields200, form a single jacket. Preferably, the inner andouter layers110 and120 are extruded with theshields200, such that the layers and shields melt together to form the jacket. Alternatively, thelayers110 and120 and theshields200 may be bonded to one another by any known method, such as adhesive and the like. The inner andouter layers110 and120 may be formed of any known jacket material for communication cabling, such as PVC, HDPE, FEP, flame retardant PE, or the like. Because the one ormore shields200 are incorporated in thejacket100, a separate shielding layer surrounding theconductor pairs102 is not required. Also, theinner layer110 acts as a barrier between the one ormore shields200, thereby eliminating the need for a separate barrier layer. The overall diameter of the cable is reduced because less jacket material is required for thejacket100 and both the shielding and barrier layers have been eliminated.
• Theshield200 may be a shielding layer or tape made up of asubstrate202, as seen inFIG. 2, that is preferably of the same type and chemical nature of the material of thejacket100. For example, if the material of thejacket100 is PVC, then the substrate of the shielding tape is also PVC. That allows the jacketing material to properly bond with the substrate material of theshielding tape200 to form thesingle jacket100.
• Theshielding tape200 may include a plurality ofconductive segments204, such as aluminum, copper, ferrite, or any other conductive bricks. Thesegments204 may be applied to the surface of thesubstrate202 by adhesive, heat pressing, laser ablation, vapor deposition, or by spraying conductive particles onto thesubstrate202 to form the segments. Alternatively, theconductive segments204 can be sandwiched between two layers of thesubstrate200. Theconductive segments204 are preferably spaced from each other, thereby forming a discontinuous shield, as seen inFIG. 2. Although theconductive segments204 are shown as having a substantially rectangular shape, thesegments204 may have other shapes, such as square, trapezoidal, diamond, and the like. Additionally, thesegments204 may all be substantially the same size or may have various sizes. Theconductive segments204 may also be placed in a random pattern along the substrate.
• According to an exemplary method of the present invention, one or more of theshielding tapes200 is inserted into thejacket100 during the jacket extrusion process. Specifically, theshielding tape200 is pulled through the actual die/crosshead or tooling for thejacket100 in between the inner andouter layers110 and120 of the jacket. Thus, one ormore shielding tapes200 may be sandwiched by the inner andouter jacket layers110 and120. During that co-extrusion process, the material of thejacket layers110 and120 is in a molten or near molten state. When the shielding tape ortapes200 come into contact with the molten jacket material, bonding/melting of the shielding tape or tapes occurs within the jacket material. Alternatively, the two jacket layers may be preformed materials (not in a molten state) that are bonded together.
• Preferably, the material of thejacket100 and itslayers110 and120 are the same as thesubstrate202 of theshielding tapes200, so that the materials readily mix and bond to each other. This creates a near seamless dispersing of theshielding tape200 within thejacket100. Alternatively, thejacket layers110 and120 may be formed of a different material than thesubstrate202 of theshielding tapes200. In that case, thejacket layers110 and120 may be bonded to thesubstrates202 of the shielding tapes by any know method, such as adhesive bonding, high pressure, or the like. On the other hand, theouter jacket layer120 may suffice as a barrier to hold theshielding tape200 and theinner jacket layer110 in place.
• During the co-extrusion process, theconductive segments204 are encased in thejacket100 while also maintaining the original orientation of the segments on theshielding tape200. That orientation of the segments insures consistent electrical properties of the cable, such as return loss and attenuation. Thus, the method of the present invention allowsconductive shielding segments204 to be inserted into thejacket100 without negatively impacting the physical properties of the jacket, such as tensile strength and elongation. That is because the near continuous material of jacket100 (incorporated with one or more shielding tapes200) maintains its original tensile strength as well as elongation properties.
• Referring toFIG. 3, a plurality of the cables C may be bundled together. An optional outer jacket300 may be provided that encloses the bundle cables C. Each cable C includes thejacket100, as described above.
• While particular embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.

Claims (30)

1. A cable jacket, comprising:

first and second jacket layers each formed of a jacket material; and

at least one shielding tape embedded between said first and second jacket layers, said at least one shielding tape being formed of a substrate material, said substrate material having at least one conductive segment.

2. A cable jacket according toclaim 1, wherein

said jacket material and said substrate material are the same material.

3. A cable jacket according toclaim 1, wherein

said at least one conductive segment forms a substantially rectangular brick.

4. A cable jacket according toclaim 1, wherein

said substrate material includes a plurality conductive segments that are disposed in a spaced discontinuous arrangement.

5. A cable jacket according toclaim 4, wherein

each of said conductive segments is formed of one of aluminum, copper, or ferrite.

6. A cable jacket according toclaim 4, wherein

said conductive segments are bonded to said substrate of said shielding tape by adhesive, heat pressing or laser ablation.

7. A cable jacket according toclaim 4, wherein

said conductive segments are embedded in said substrate of said shielding tape.

8. A cable jacket according toclaim 4, wherein

conductive particles are sprayed onto said substrate of said shielding tape to form said conductive segments.

9. A cable jacket according toclaim 1, further comprising

a plurality of shielding tapes embedded between said first and second jacket layers, each of said shielding tapes having a substrate material, each substrate material having a plurality of conductive segments disposed in a spaced discontinuous arrangement, and said substrate material of said plurality of shielding tapes and said jacket material is the same.

10. A cable, comprising:

at least one twisted pair of insulated conductors;

a jacket enclosing said at least one twisted pair of insulated conductors, said jacket being formed of a jacket material; and

at least one shielding tape embedded in said jacket, said at least one shielding tape being formed of a substrate material, said substrate material having at least one conductive segment,

whereby the cable does not include a barrier layer enclosed by said jacket.

11. A cable according toclaim 10, wherein

said jacket material and said substrate material are the same material.

12. A cable according toclaim 10, wherein

said substrate material includes a plurality conductive segments that are disposed in a spaced discontinuous arrangement.

13. A cable according toclaim 12, wherein

each of said conductive segments is formed of one of aluminum, copper, or ferrite.

14. A cable according toclaim 10, further comprising

a plurality of shielding tapes embedded in said jacket, each of said shielding tapes having a substrate material, each substrate material having a plurality of conductive segments disposed in a spaced discontinuous arrangement, and said substrate material of said plurality of shielding tapes and said jacket material is the same.

15. A cable according toclaim 10, further comprising

a plurality of twisted pairs of conductors enclosed by said jacket.

16. A cable according toclaim 15, further comprising

a separator disposed between said plurality of twisted pairs of conductors.

17. A cable assembly, comprising:

a plurality of cables, said plurality of cables being bundled together, each of said plurality of cables including:

at least one twisted pair of insulated conductors,

a jacket enclosing said at least one twisted pair of insulated conductors, said jacket being formed of a jacket material, and

at least one shielding tape embedded in said jacket, said at least one shielding tape being formed of a substrate material, said substrate material having at least one conductive segment, whereby the cable does not include a barrier layer enclosed by said jacket.

18. A cable assembly according toclaim 17, wherein

said jacket material and said substrate material are the same material.

19. A cable assembly according toclaim 17, wherein

said substrate material includes a plurality conductive segments that are disposed in a spaced discontinuous arrangement.

20. A cable assembly according toclaim 17, further comprising

a plurality of shielding tapes embedded in said jacket of each of said plurality of cables, each of said shielding tapes having a substrate material, each substrate material having a plurality of conductive segments disposed in a spaced discontinuous arrangement, and said substrate material of said plurality of shielding tapes and said jacket material is the same.

21. A cable assembly according toclaim 17, further comprising

a plurality of twisted pairs of conductors enclosed by said jacket of each of said plurality of cables.

22. A cable assembly according toclaim 21, further comprising

a separator disposed between said plurality of twisted pairs of conductors.

23. A cable assembly according toclaim 21, further comprising

an outer jacket enclosing said plurality of cables.

24. A method for making a cable jacket, comprising the steps of:

providing at least one shielding tape having a substrate formed of a substrate material, said substrate including at least one conductive segment;

inserting the at least one shielding tape between first and second jacket layers of the cable jacket, each of said first and second jacket layers being formed of a jacket material; and

co-extruding the at least one shielding tape with the first and second jacket layers, wherein the substrate material of the at least one shielding tape and the jacket material of the first and second jacket layers are the same such that during the co-extrusion step, the substrate and first and second jacket layers bond together.

25. A method according toclaim 24, further comprising the step of

providing a plurality of shielding tapes, each shielding tape having a substrate formed of a substrate material, and each substrate including a plurality of conductive segments in a spaced discontinuous arrangement;

inserting the plurality of shielding tapes between the first and second jacket layers of the cable jacket; and

co-extruding the plurality of shielding tapes with the first and second jacket layers, wherein the substrate material of the shielding tapes and the jacket material of the first and second jacket layers are the same such that during the co-extrusion step, the substrates and first and second jacket layers are bonded together.

26. A method according toclaim 24, wherein

said substrate includes a plurality of conductive segments positioned in a spaced discontinuous arrangement.

27. A method according toclaim 25, wherein

the position of the conductive segments is the same before and after the co-extrusion step.

28. A method according toclaim 25, further comprising the step of

bonding said conductive segments to said shielding tape by adhesive, heat pressing, or laser ablation.

29. A method according toclaim 25, further comprising the step of

spraying conductive particles onto said shielding tape to form said conductive segments.

30. A method according toclaim 25, further comprising the step of

embedding said conductive particles in said shielding tape.

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