CN113646852B

CN113646852B - Low cost extrudable separator made from slit tape

Info

Publication number: CN113646852B
Application number: CN202080025937.8A
Authority: CN
Inventors: W·C·霍普金森; T·M·黑斯
Original assignee: Commscope Technologies LLC
Current assignee: Commscope Technologies LLC
Priority date: 2019-04-08
Filing date: 2020-03-30
Publication date: 2023-09-22
Anticipated expiration: 2040-03-30
Also published as: CN113646852A; MX2021012306A; WO2020210075A1; EP3953951A1

Abstract

A dielectric isolator for a twisted pair cable includes a body formed as an elongated strip having a top surface, a bottom surface, a first side edge, and a second side edge. A first slot is formed in the first side edge and extends toward the center of the isolator to at least half way. A second groove is formed in the second side edge and extends toward the center of the separator at least halfway. During cable manufacture, the first wedge and the second wedge open the first slot and the second slot. The first twisted pair and the second twisted pair are inserted into the open first slot and second slot, respectively. The third twisted pair and the fourth twisted pair reside on the top surface and the bottom surface, respectively. The isolator has the cost and reel storage savings of flat separator tape while providing the internal crosstalk performance of the isolator.

Description

Low cost extrudable separator made from slit tape

Technical Field

The present invention relates to a twisted pair cable for communication of high-speed signals, such as a Local Area Network (LAN) cable. More particularly, the present invention relates to a twisted pair cable having an isolator between twisted pairs within the cable, wherein the isolator separates each of the twisted pairs from the other twisted pairs of the cable, and wherein the isolator is initially formed as a relatively flat member, such as a ribbon with slits in its thickness.

Background

With the growing use of computers for homes and offices, there has been a growing need for cables that can be used to connect peripheral equipment to computers and to connect multiple computers and peripheral equipment into a common network. Computers and peripheral devices today operate at ever increasing data transfer rates. Accordingly, there is a continuing need to develop cables that can operate substantially error-free at higher bit rates by meeting a variety of enhanced performance criteria, such as reduction of internal and external crosstalk when the cable is in high cable density applications (e.g., wired alongside other cables).

Fig. 1 and 2 show a typical shielded twisted pair cable 1 and a stranding scheme employed for four twisted pair wires (first twisted pair a, second twisted pair B, third twisted pair C, and fourth twisted pair D). Dielectric separator 3 separates twisted pair a from twisted pairs B, C and D, separates twisted pair B from twisted pairs C and D, and also separates twisted pair C from twisted pair D. The separator 3 may also be considered a groove, a star-shaped separator or a plus-shaped separator.

Twisted pairs A, B, C and D in combination with separator 3 can be twisted in the direction of arrow 5 (e.g., opposite the direction of twist of twisted pairs A, B, C and D) to form a twisted core. The core of the strand is surrounded by a shielding layer 7. The shielding layer 7 may be formed of a conductive foil and the edges of the foil may partly overlap at the area 9. A dielectric outer sheath 11 then surrounds the shielding layer 7.

Each twisted pair A, B, C and D includes two insulated conductors. Specifically, the first twisted pair a includes a first insulated conductor 13 and a second insulated conductor 15. The second twisted pair B includes a third insulated conductor 17 and a fourth insulated conductor 19. The third twisted pair C includes a fifth insulated conductor 21 and a sixth insulated conductor 23. The fourth twisted pair D includes a seventh insulated conductor 25 and an eighth insulated conductor 27.

Each twisted pair A, B, C and D is formed by continuously twisting its two insulated conductors around each other. For the first twisted pair a, the first conductor 13 and the second conductor 15 are completely twisted with each other by three hundred sixty degrees (a) at a first interval w along the length of the cable 1. For the second twisted pair B, the third conductor 17 and the fourth conductor 19 are completely twisted with each other at a second interval x three hundred sixty degrees (B) along the length of the cable 1. For the third twisted pair C, the fifth conductor 21 and the sixth conductor 23 are completely twisted with each other at a third interval y along the length of the cable 1 by three hundred sixty degrees (C). For the fourth twisted pair D, the seventh conductor 25 and the eighth conductor 27 are fully twisted with each other at a fourth interval z by three hundred sixty degrees (D) along the length of the cable 1.

Each of the twisted pairs A, B, C and D has a fixed lay w, x, y, z, respectively. Each of the pitches w, x, y, z is different from the pitches of the other twisted pairs. As is known in the art, such an arrangement helps reduce crosstalk between twisted pairs within the cable 1, which is referred to as internal crosstalk. In one embodiment of the prior art, each of the twisted pairs A, B, C and D has a unique fixed lay length of slightly more or less than 0.500 inches. Table 1 below summarizes the lay ranges for twisted pairs A, B, C and D.

TABLE 1

Twisted pair	Length of twist	Minimum strand length	Maximum strand length
				A	0.440	0.430	0.450
B	0.410	0.400	0.420
				C	0.596	0.580	0.610
D	0.670	0.650	0.690

Disclosure of Invention

The applicant has realized that the separator 3 is a rather expensive element of the cable core. Furthermore, the separator 3 is an extruded element with four protruding fins and cannot be wound well on a reel, for example there are many air gaps in the wound separator 3. Thus, a shorter length of the separator 3 can be wound onto a reel of a given size.

Extruding flat separator strips is relatively inexpensive compared to the plus sign separator 3. Moreover, the extruded flat separator band is wound well on a spool with much less air gaps. Thus, a significantly longer flat separator band may be present on the same given size spool.

However, there are significant drawbacks to flat separator strips. The flat separator strip separates only two of the twisted pairs from the other two, e.g., separates twisted pairs a and C from twisted pairs B and D. Thus, the flat separator band is inferior in reducing internal crosstalk as compared to the separator 3 in fig. 1 and 2.

The applicant has discovered a new separator that can be extruded as a flat strip with slits formed in its thickness. Alternatively, the new separator may be extruded as a flat strip and slits may be formed in the thickness of the strip by a cutting operation. In a preferred embodiment, two slits are formed in the thickness of the new separator, one slit on each lateral side of the new separator. The new separator may be wound on a spool in the same manner as a conventional flat separator tape. Thus, the new separator does not include much air in the windings on the reel compared to the old separator 3 of fig. 1-2, and a longer new separator can be wound on a reel of the same given size.

In the manufacture of the cable, new isolators are fed from reels to the cable assembly area. In the cable assembly area, the wedge opens the slit. The first twisted pair is inserted in a first one of the open wedges, the second twisted pair is inserted in a second one of the open slits, the third twisted pair is placed on top of the new separator, and the fourth twisted pair is placed under the new separator. Next, an optional shielding layer or core cladding surrounds the cable core, and finally an outer jacket is extruded onto the cable core.

The present invention provides cost savings and storage savings for flat separator strips while at the same time providing internal crosstalk performance for the separator 3.

These and other objects are achieved by an isolator for a twisted pair cable, the isolator comprising: a body formed as an elongated strip having a top surface and a bottom surface, wherein a distance between the top surface and the bottom surface defines a thickness of the separator; a first side edge and a second side edge formed on the body, wherein a distance between the first side edge and the second side edge defines a width of the separator; a first groove formed in the first side edge and extending into the main body in the direction of the width of the separator; and a second groove formed in the second side edge and extending into the main body in the direction of the width of the separator.

Further, these and other objects are achieved by a method of forming a twisted pair cable, the method comprising: providing an isolator, the isolator comprising: a body formed as an elongated strip having a top surface and a bottom surface, wherein a distance between the top surface and the bottom surface defines a thickness of the separator; a first side edge and a second side edge formed on the main body, wherein a distance between the first side edge and the second side edge defines a width of the separator; a first groove formed in the first side edge and extending into the main body in a direction of a width of the separator; and a second groove formed in the second side edge and extending into the main body in a direction of a width of the separator; feeding the first twisted pair, the second twisted pair, the third twisted pair, and the fourth twisted pair to a cable assembly area; feeding an isolator to a cable assembly area; inserting the first wedge into the first groove and opening the first groove as the isolator passes through the cable assembly area; inserting a second wedge into the second groove and opening the second groove as the isolator passes through the cable assembly area; placing a first twisted pair into an open first slot of an isolator; placing a second twisted pair adjacent to a top surface of the isolator; placing the third twisted pair into an open second slot of the separator; placing the fourth twisted pair adjacent to the bottom surface of the separator; and extruding an outer jacket over the separator and the first, second, third and fourth twisted pairs.

Further, these and other objects are achieved by a cable comprising: a first conductor; a first insulating material surrounding the first conductor to form a first insulating conductor; a second conductor; and a second insulating material surrounding the second conductor to form a second insulated conductor, wherein the first and second insulated conductors are twisted with each other to form a first twisted pair; a third conductor; a third insulating material surrounding the third conductor to form a third insulated conductor; a fourth conductor; and a fourth insulating material surrounding the fourth conductor to form a fourth insulated conductor, wherein the third and fourth insulated conductors are stranded with each other to form a second twisted pair; a fifth conductor; a fifth insulating material surrounding the fifth conductor to form a fifth insulating conductor; a sixth conductor; and a sixth insulating material surrounding the sixth conductor to form a sixth insulated conductor, wherein the fifth insulated conductor and the sixth insulated conductor are twisted with each other to form a third twisted pair; a seventh conductor; a seventh insulating material surrounding the seventh conductor to form a seventh insulating conductor; an eighth conductor; and an eighth insulating material surrounding the eighth conductor to form an eighth insulated conductor, wherein the seventh insulated conductor and the eighth insulated conductor are twisted with each other to form a fourth twisted pair; an isolator separating the first twisted pair from the second twisted pair, a third twisted pair and a fourth twisted pair, separating the second twisted pair from the third twisted pair and the fourth twisted pair, and further separating the third twisted pair from the fourth twisted pair, wherein the isolator has a closed first notch formed on a top surface thereof and the first twisted pair is adjacent to the top surface, and a closed second notch on a bottom surface thereof and the third twisted pair is adjacent to the bottom surface; and a jacket surrounding the separator, the first twisted pair, the second twisted pair, the third twisted pair, and the fourth twisted pair.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Drawings

The present invention will become more fully understood from the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and the detailed description given hereinafter, and wherein:

fig. 1 is a perspective view of a shielded twisted pair cable according to the prior art;

FIG. 2 is a cross-sectional view taken along line II- -II in FIG. 1;

fig. 3 is a block diagram of a spool fed to an isolator of a cable assembly unit according to a first embodiment of the present invention;

FIG. 4 is a cross-sectional view of the separator taken along line IV-IV in FIG. 3;

FIG. 5 is a cross-sectional view of the isolator of FIG. 4 after passage through a cable assembly unit;

fig. 6 is a block diagram of a machine for producing twisted pair cable using the separator of fig. 3-5;

FIG. 6A is a close-up perspective view of the interaction of the first wedge and the second wedge with the isolator of FIGS. 3-5;

FIG. 7 is a cross-sectional view of a second embodiment of an isolator similar to that of FIG. 3;

FIG. 8 is a cross-sectional view of the isolator of FIG. 7 after passage through a cable assembly unit;

FIG. 9 is a cross-sectional view of a third embodiment of an isolator similar to that of FIG. 3;

FIG. 10 is a cross-sectional view of the isolator of FIG. 9 after passage through a cable assembly unit;

FIG. 11 is a cross-sectional view of a fourth embodiment of an isolator similar to that of FIG. 3;

FIG. 12 is a cross-sectional view of the isolator of FIG. 11 after passage through a cable assembly unit;

fig. 13 is a cross-sectional view of a twisted pair cable having the separator of fig. 11-12;

FIG. 14 is a block diagram of a machine producing sheets of the separator according to FIGS. 11-12;

FIG. 15 is a close-up view of the encircled portion XV in FIG. 14 showing details of the extrusion die; and

fig. 16 is a perspective view of a portion of a sheet of separator produced by portion XV of the extrusion die illustrated in fig. 15.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. The dashed lines illustrate optional features or operations unless specified otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as "between X and Y" and "between about X and Y" should be construed to include X and Y. As used herein, phrases such as "between about X and Y" mean "between about X and about Y". As used herein, phrases such as "from about X to Y" mean "from about X to about Y".

It will be understood that when an element is referred to as being "on," "attached" to, "connected" to, "coupled" with, "contacting" another element, etc., it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on," "directly attached to," directly connected to, "directly coupled with," or "directly contacting" another element, there are no intervening elements present. Those skilled in the art will also appreciate that a reference to a structure or feature that is disposed "adjacent" another feature may have portions that overlap or underlie the adjacent feature.

Spatially relative terms, such as "under", "below", "lower", "above", "upper", "lateral", "left", "right", and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Devices may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors of relative spatial descriptors used herein interpreted accordingly.

Fig. 3 is a block diagram of a spool or reel 31 that winds a separator 33A according to a first embodiment of the present invention. The isolator 33A is fed to the cable assembly area 35 and may pass over one or more power or idler wheels or rollers 37. A more description will be given about the cable assembly region 35 with respect to fig. 6.

Fig. 4 is a cross-sectional view of the separator 33A taken along the line IV-IV in fig. 3. The isolator 33A includes a body 39, the body 39 being formed as an elongated strip having a top surface 41 and a bottom surface 43. A first distance D1 exists between the top surface 41 and the bottom surface 43 and defines the thickness of the separator 33A. A first side edge 45 and a second side edge 47 are formed on the body 39. A second distance D2 exists between the first side edge 45 and the second side edge 47 and defines the width of the separator 33A.

A first slot 49 is formed in the first side edge 45. The first groove 49 extends into the main body 39 in the direction of the width of the separator 33A. More specifically, the first groove 49 extends parallel to the top surface 41 and the bottom surface 43 toward the center 53 of the separator 33A. The center 53 extends along a central or longitudinal axis of the separator 33A that runs along the length of the separator 33A. The first groove 49 extends into the body 39 at least half way to the center 53 of the isolator 33A, e.g., greater than 75% of the way to the center 53, such as about 85% of the way to the center 53, and extends along the entire length of the isolator 33A. The first slot 49 creates a first leg 55 and a second leg 57.

A second slot 51 is formed in the second side edge 47. The second groove 51 extends into the main body 39 in the direction of the width of the separator 33A. More specifically, the second groove 51 extends parallel to the top surface 41 and the bottom surface 43 toward the center 53 of the separator 33A. The second groove 51 extends into the body 39 at least half way to the center 53 of the isolator 33A, e.g., greater than 75% of the way to the center 53, such as about 85% of the way to the center 53, and extends along the entire length of the isolator 33A. The second slot 51 creates a third leg 59 and a fourth leg 61.

In a preferred embodiment, the body 39 is formed of a dielectric material. For example, the body 39 may be formed of void-free (solid) or foamed polyethylene or void-free or foamed Fluorinated Ethylene Propylene (FEP), where "foamed" means that gas bubbles, such as air bubbles, are purposely introduced into the material to reduce the overall dielectric constant of the separator 33A. Of course, other materials may be suitable for the body 39 of the separator 33A.

In preferred embodiments, the thickness, represented by distance Dl, is between 9 and 18 mils, such as between 10 and 15 mils, or about 12 mils, or the like. The width represented by distance D2 is between 90 and 130 mils, such as between 100 and 120 mils, or about 110 mils.

Fig. 6 is a block diagram of a machine 63 for producing twisted pair cable 65 using the separator 33A of fig. 3-5. In addition to the elements of fig. 3, the machine 63 comprises: a first spool 67 containing a first twisted pair a, a second spool 69 containing a second twisted pair B, a third spool 71 containing a third twisted pair C, and a fourth spool 73 containing a fourth twisted pair D.

During formation of twisted pair cable 65, first twisted pair a, second twisted pair B, third twisted pair C, and fourth twisted pair D are fed to cable assembly area 35 along with separator 33A. As best seen in the close-up view of fig. 6A, when the isolator 33A enters the cable assembly area 35, the first wedge 75 is inserted into the first slot 49 and opens the first slot 49 as the isolator 33A passes through the cable assembly area 35. A separate second wedge 77 is located adjacent the second side edge 47 of the isolator 33A. As the isolator 33A passes through the cable assembly area 35, the second wedge 77 is inserted into the second slot 51 and opens the second slot 51.

The isolator 33A achieves the configuration shown in fig. 5, as the first wedge 75 and the second wedge 77 open the first slot 49 and the second slot 51. In other words, the portion of the isolator 33A to the right (upstream) of the first and second wedges 75, 77 in fig. 6A has the cross section of fig. 4, and the portion of the isolator 33A to the left (downstream) of the first and second wedges 75, 77 in fig. 6A has the cross section of fig. 5. When the first and second wedges 75, 77 open the first and second slots 49, 51, the body 39 of the isolator 33A may undergo permanent elastic deformation such as compression and extension. In other words, the material forming the main body 39 of the separator 33A has low elasticity and tends to maintain shape deformation, as shown in fig. 5.

As best seen in fig. 5, the angle between the first leg 55 and the second leg 57 is approximately ninety degrees, and the angle between the third leg 59 and the fourth leg 61 is approximately ninety degrees. Opening the first and second slots 49, 51 results in a first arcuate portion 41A in the top surface 41 such that the angle between the first and third legs 55, 59 is from one hundred eighty degrees to about ninety degrees. Moreover, opening the first and second slots 49, 51 results in a second arcuate portion 43A in the bottom surface 43 such that the angle between the second and fourth legs 57, 61 is from one hundred eighty degrees to about ninety degrees.

Within the cable assembly area 35, a first twisted pair a is placed in an open first slot 49, a second twisted pair B is placed adjacent to the top surface 41 in the first arcuate portion 41A, a third twisted pair C is placed in an open second slot 51, and a fourth twisted pair D is placed adjacent to the bottom surface 43 in the second arcuate portion 43A. Preferably, the cable assembly area 35 applies twist to the assembled separator 33A and the first, second, third and fourth twisted pairs a, B, C and D to form a twisted core 79.

The twisted core 79 may be fed to the shielding unit 81. The shielding layer 7 is fed from the bobbin 83 into the shielding unit 81. Within the shielding unit 81, the shielding layer 7 encloses and surrounds Twisted core 79. The shielding layer 7 may further include an overlapping portion 9 as shown in fig. 1-2 to form a shielding stranded core 85. The shielding layer 7 may be formed of a conductive layer on a non-conductive layer. One suitable material for the conductive layer is aluminum foil, although other materials may be selected. One suitable material for the non-conductive layer is a polyester film or biaxially oriented polyethylene terephthalate, for example

The shield lay core 85 is fed into an extruder 87. Within the extruder 87, the outer jacket 11 is extruded over the separator 33A, the first twisted pair a, the second twisted pair B, the third twisted pair C and the fourth twisted pair D, and the shielding 7 to form the twisted pair cable 65. The outer sheath 11 may be formed of polyvinyl chloride (PVC), low smoke zero halogen, polyethylene (PE), fluorinated Ethylene Propylene (FEP), polyvinylidene fluoride (PVDF), ethylene Chlorotrifluoroethylene (ECTFE), or other foamed or void-free materials commonly found in wiring technology.

Twisted pair cable 65 is typically passed through a cold water bath 88 to cure the outer jacket 11 and then accumulated onto a spool 89. The machinery for making the twisted pair cable 65 is substantially known in the art, except for the first wedge 75 and the second wedge 77 that open the first slot 49 and the second slot 51.

Fig. 7 is a sectional view of the separator 33B according to the second embodiment. The isolator 33B includes a body 39B, the body 39B being formed as an elongated strip having a top surface 41B and a bottom surface 43B. A first distance D3 exists between the top surface 41B and the bottom surface 43B and defines the thickness of the separator 33B. A first side edge 45B and a second side edge 47B are formed on the main body 39B. A second distance D4 exists between the first side edge 45B and the second side edge 47B and defines the width of the separator 33B.

A first groove 49B is formed in the first side edge 45B. The first groove 49B extends into the main body 39B in the direction of the width of the separator 33B. More specifically, the first groove 49B extends toward the center 53B of the separator 33B in parallel with the top surface 41B and the bottom surface 43B. The first groove 49B extends into the body 39B at least half way to the center 53B of the isolator 33B, e.g., greater than 75% of the way to the center 53B, such as about 85% of the way to the center 53B, and along the entire length of the isolator 33B. The first slot 49B creates a first leg 55B and a second leg 57B.

A second groove 51B is formed in the second side edge 47B. The second groove 51B extends into the main body 39B in the direction of the width of the separator 33B. More specifically, the second groove 51B extends toward the center 53B of the separator 33B in parallel with the top surface 41B and the bottom surface 43B. The second groove 51B extends into the body 39B at least half way to the center 53B of the isolator 33B, e.g., greater than 75% of the way to the center 53B, such as about 85% of the way to the center 53B, and along the entire length of the isolator 33B. The second slot 51B creates a third leg 59B and a fourth leg 61B.

The distances D3 and D4 may be in approximately the same ranges as described above for distances D1 and D2, respectively. Also, the material for the body 39B may be the same material for the body 39. The main difference between the embodiment of fig. 7 and the embodiment of fig. 4 is that the top surface 41B is formed by a first planar surface 91 and a second planar surface 93 and includes a first step 95 between the first planar surface 91 and the second planar surface 93. Further, the bottom surface 43B is formed by the third flat surface 97 and the fourth flat surface 99, and includes a second step 101 between the third flat surface 97 and the fourth flat surface 99.

The first step 95 and the second step 101 provide a natural bending point when the first groove 49B and the second groove 51B are opened by the first wedge 75 and the second wedge 77. Thus, after opening of the first and second slots 49 and 51, the gradual curves of the first and second arcuate portions 41A and 43A in fig. 5 tend to decrease toward more angular bends, like the ninety degree angles 103 and 105 illustrated in fig. 8. However, fig. 8 still illustrates the elongation deformation in regions 107 and 109 when the isolator 33B is opened by the first wedge 75 and the second wedge 77. The separator 33B of fig. 7 and 8 may be used in conjunction with the machine 63 of fig. 6 to form a twisted pair cable 65B.

Fig. 9 is a sectional view of the separator 33C according to the third embodiment. The separator 33C includes a body 39C, the body 39C being formed as an elongated strip having a top surface 41C and a bottom surface 43C. A first distance D1 exists between the top surface 41C and the bottom surface 43C and defines the thickness of the separator 33C. A first side edge 45C and a second side edge 47C are formed on the main body 39C. A second distance D2 exists between the first side edge 45C and the second side edge 47C and defines the width of the separator 33C.

A first slot 49C is formed in the first side edge 45C. The first groove 49C extends into the main body 39C in the direction of the width of the separator 33C. More specifically, the first groove 49C extends toward the center 53C of the separator 33C in parallel with the top surface 41C and the bottom surface 43C. The first slot 49C extends into the body 39C at least half way to the center 53C of the isolator 33C, e.g., greater than 75% of the way to the center 53C, such as about 85% of the way to the center 53C, and along the entire length of the isolator 33C. The first slot 49C creates a first leg 55C and a second leg 57C.

A second groove 51C is formed in the second side edge 47C. The second groove 51C extends into the main body 39C in the direction of the width of the separator 33C. More specifically, the second groove 51C extends toward the center 53C of the separator 33C in parallel with the top surface 41C and the bottom surface 43C. The second groove 51C extends into the body 39C at least half way to the center 53C of the isolator 33C, e.g., greater than 75% of the way to the center 53C, such as about 85% of the way to the center 53C, and along the entire length of the isolator 33C. The second slot 51C creates a third leg 59C and a fourth leg 61C.

The material for the body 39C may be the same material for the body 39. The main difference between the embodiment of fig. 9 and the embodiment of fig. 4 is that the top surface 41C includes a first recessed area 107 near the midpoint between the first side edge 45C and the second side edge 47C, and the bottom surface 43C includes a second recessed area 109 near the midpoint between the first side edge 45C and the second side edge 47C.

In the illustrated embodiment, the first recessed area 107 is a first v-shaped notch and the second recessed area 109 is a second v-shaped notch. The first v-shaped notch is formed by the intersection of a first inclined surface 111 and a second inclined surface 113, wherein the first inclined surface 111 and the second inclined surface 113 intersect at an angle of about forty-five degrees. The second v-notch is formed by the intersection of the third angled surface 115 and the fourth angled surface 117, wherein the third angled surface 115 and the fourth angled surface 117 intersect at an angle of approximately forty-five degrees.

The first v-shaped notch and the second v-shaped notch provide a natural point of bending when the first slot 49C and the second slot 51C are opened by the first wedge 75 and the second wedge 77. In this way, after opening of the first and second slots 49C, 51C, the elongation and compression of the material forming the body 39C is reduced, as best seen in fig. 10. The separator 33C of fig. 9 and 10 may be used in conjunction with the machine 63 of fig. 6 to form a twisted pair cable 65C.

Fig. 11 is a cross-sectional view of an isolator 33D according to the fourth embodiment. The separator 33D includes a main body 39D, which main body 39D is formed as an elongated strip having a top surface 41D and a bottom surface 43D. A first distance D1 exists between the top surface 41D and the bottom surface 43D and defines the thickness of the separator 33D. A first side edge 45D and a second side edge 47D are formed on the main body 39D. A second distance D2 exists between the first side edge 45D and the second side edge 47D and defines the width of the separator 33D.

A first slot 49D is formed in the first side edge 45D. The first groove 49D extends into the main body 39D in the direction of the width of the separator 33D. More specifically, the first groove 49D extends toward the center 53D of the separator 33D in parallel with the top surface 41D and the bottom surface 43D. The first slot 49D extends into the body 39D at least half way to the center 53D of the isolator 33D, e.g., more than 75% of the way to the center 53D, such as about 85% of the way to the center 53D, and along the entire length of the isolator 33D. The first slot 49D creates a first leg 55D and a second leg 57D.

A second groove 51D is formed in the second side edge 47D. The second groove 51D extends into the main body 39D in the direction of the width of the separator 33D. More specifically, the second groove 51D extends toward the center 53D of the separator 33D in parallel with the top surface 41D and the bottom surface 43D. The second groove 51D extends into the body 39D at least half way to the center 53D of the isolator 33D, e.g., more than 75% of the way to the center 53D, such as about 85% of the way to the center 53D, and along the entire length of the isolator 33D. The second slot 51D creates a third leg 59D and a fourth leg 61D.

The material for the body 39D may be the same material as that for the body 39. The main difference between the embodiment of fig. 11 and the embodiment of fig. 4 is that the top surface 41D includes a first recessed area 119 near the midpoint between the first side edge 45D and the second side edge 47D, and the bottom surface 43D includes a second recessed area 121 near the midpoint between the first side edge 45D and the second side edge 47D.

In the illustrated embodiment, the first recessed area 119 is a first v-shaped notch and the second recessed area 121 is a second v-shaped notch. The first v-shaped notch is formed by the intersection of a first angled surface 123 and a second angled surface 125, wherein the first angled surface 123 and the second angled surface 125 intersect at an angle of about ninety degrees. The second v-notch is formed by the intersection of the third angled surface 127 and the fourth angled surface 129, wherein the third angled surface 127 and the fourth angled surface 129 intersect at an angle of approximately ninety degrees.

The first v-shaped notch and the second v-shaped notch provide a natural point of bending when the first slot 49D and the second slot 51D are opened by the first wedge 75 and the second wedge 77. In this way, after opening of the first and second slots 49D, 51D, the elongation and compression of the material forming the body 39D is reduced, as best seen in fig. 12. As also seen in fig. 12, the angle between the first leg 55D and the third leg 59D is approximately ninety degrees, and the angle between the second leg 57D and the fourth leg 61D is approximately ninety degrees. Likewise, the angle between the first leg 55D and the second leg 57D is about ninety degrees, and the angle between the third leg 59D and the fourth leg 61D is about ninety degrees. The separator 33D of fig. 11 and 12 may be used in conjunction with the machine 63 of fig. 6 to form a twisted pair cable 65D.

Fig. 13 is a cross-sectional view of twisted pair cable 65D. Twisted pair cable 65D includes a first twisted pair 131. The first twisted pair 131 includes a first insulated conductor 135 formed by a first insulating material 135A surrounding a first conductor 135B and a second insulated conductor 137 formed by a second insulating material 137A surrounding a second conductor 137B. The first insulated conductor 135 and the second insulated conductor 137 are twisted with each other to form the first twisted pair 131.

The second twisted pair 139 includes a third insulated conductor 141 formed by surrounding a third conductor with a third insulating material and a fourth insulated conductor 143 formed by surrounding a fourth conductor with a fourth insulating material, wherein the third insulated conductor 141 and the fourth insulated conductor 143 are twisted with each other to form the second twisted pair 139.

The third twisted pair 145 includes a fifth insulated conductor 147 formed by surrounding the fifth conductor with a fifth insulating material and a sixth insulated conductor 149 formed by surrounding the sixth conductor with a sixth insulating material, wherein the fifth insulated conductor 147 and the sixth insulated conductor 149 are twisted with each other to form the third twisted pair 145.

The fourth twisted pair 151 includes a seventh insulated conductor 153 formed by surrounding the seventh conductor with a seventh insulating material and an eighth insulated conductor 155 formed by surrounding the eighth conductor with an eighth insulating material, wherein the seventh insulated conductor 153 and the eighth insulated conductor 155 are twisted with each other to form the fourth twisted pair 151.

The twist lengths w, x, y, and z of the first twisted pair 131, the second twisted pair 139, the third twisted pair 145, and the fourth twisted pair 151 may be the same as those listed in table 1 for the twisted pairs A, B, C and D, respectively. For example, the first twist length w of the first twisted pair 131 may be shorter than the third twist length y of the third twisted pair 145 and the second twist length x of the second twisted pair 139 may be shorter than the fourth twist length z of the fourth twisted pair 151. It should be noted that other strand lengths than those listed in table 1 may be employed while practicing the benefits of the present invention.

The first to eighth insulating materials may be formed of a flexible plastic material having flame retardant and smoke suppressing properties, such as a polymer or foamed polymer common in the wiring art, like Fluorinated Ethylene Propylene (FEP), polyethylene (PE), or polypropylene (PP). The radial thickness of the first through eighth insulative materials will typically be greater than seven mils, such as about ten mils or about eleven mils. The first to eighth conductors may be void-free or stranded, and may be formed of a conductive metal or alloy such as copper. In one embodiment, the first conductor to the eighth conductor are each approximately twenty-three gauge copper wire without voids.

Similar to fig. 1, the cable cores of twisted pair cable 65D may be twisted in the direction of arrow 30 to form core strands. In the illustrated embodiment, the direction 30 is opposite to the twist direction of the first 131, second 139, third 145, and fourth 151 twisted pairs and may provide advantages as discussed in the assignee's U.S. patent 6,770,819, which is incorporated herein by reference. However, this is not a necessary feature, as the advantages of the present invention will still be apparent in the case where the direction 30 of the core strand is the same as the twisted direction of the twisted pair.

The separator 33D separates the first twisted pair 131 from the second twisted pair 139, the third twisted pair 145, and the fourth twisted pair 151, separates the second twisted pair 139 from the third twisted pair 145 and the fourth twisted pair 151, and also separates the third twisted pair 145 from the fourth twisted pair 151. The separator 33D has a closed first notch formed on its top surface 41D and the first twisted pair 131 is adjacent to the top surface 41D. The separator 33D also has a closed second notch on its bottom surface 43D and a third twisted pair 145 is adjacent the bottom surface 43D. The second twisted pair 139 resides in the open fourth slot 51D and the fourth twisted pair 151 resides in the open first slot 49D.

The shielding 7 surrounds the separator 33D and the first, second, third and fourth twisted pairs 131, 139, 145 and 151. The outer jacket 11 surrounds the shielding 7, the separator 33D, and the first twisted pair 131, the second twisted pair 139, the third twisted pair 145, and the fourth twisted pair 151. In all embodiments the shielding layer 7 is optional and/or may be removed, especially if a cable is employed in an environment where alien crosstalk is not a problem, e.g. the cable is not adjacent to other sources or cables that emit or are susceptible to EMF. Alien crosstalk performance in twisted pair cables as described above may be enhanced by employing a striped jacket (strapped jack), as shown in U.S. patent 5,796,046 and published U.S. application 2005/0133246, both of which are incorporated herein by reference. Alien crosstalk performance may be further enhanced by employing twisted modulation and/or core twisted modulation, as shown in the assignee's U.S. patent 6,875,928, which is incorporated herein by reference.

Fig. 14 is a block diagram of one potential embodiment of a machine 161 for producing a sheet 163 in accordance with the separator 33D of fig. 11-12. Machine 161 is an extruder 169 and receives pellets 165 from hopper 167. The pellets may be formed of polyethylene or Fluorinated Ethylene Propylene (FEP) or other such materials. Extruder 169 heats pellets 165 into a slurry. The slurry may be extruded through extrusion die 171 in void-free form or with the blowing agent. The sheet 163 of separator 33D may pass over one or more powered or idle rollers 162 and then will accumulate onto a spool 164. Of course, the sheet 163 of isolator 33D is preferably passed through a cooling device, like water bath 88 of fig. 6, prior to being stored on reel 164. The construction of the machine 161 is substantially identical to that of known machines for producing sheets of separator "tape", except for the construction of the extrusion die 171.

Fig. 15 is a close-up view of the circled portion XV in fig. 14, showing details of the extrusion die 171. The extrusion die has complementary features to produce the features of the separator 33D of fig. 11-12. For example, extrusion die 171 has "reverse" or complementary protrusions to create first and second slots 49D and 51D, first leg 55D, second leg 57D, third leg 59D, and fourth leg 61D, and first and second recessed areas 119 and 121. In practice, the sheet 163 of the separator 33D may include twenty to twenty five separators 33D arranged side by side.

Fig. 16 is a perspective view of a portion of the sheet 163 of the separator 33D produced by the portion XV of the extrusion die 171. The presented portion of the sheet 163 of the separator 33D includes three separators 33D, and portions of the separator 33B on each of the left and right sides. Arrow 173 indicates the point at which the sheet 163 of separator 33D is cut for forming individual separators 33D. The cutting is typically performed by a blade or laser as the sheet is driven through the blade or laser, and individual separators 33D are accumulated on separator reel 31, as shown in fig. 3 and 6, for shipment to customers, e.g., cable manufacturers. As mentioned previously, the extrusion and cutting processes may be performed in the same manner as previously performed for the manufacture of the separator strip, except for the shape of the extrusion die 171. Further, it would be possible to replace extrusion die 171 with a flat sheet extrusion die and cut all features of isolator 33D (first and second slots 49D and 51D and first and second recessed areas 119 and 121) into isolator 33D using a blade or laser as sheet 163 and/or individual isolators 33D are driven through the blade or laser.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. An isolator for a twisted pair cable comprising:

a body extruded as a flat ribbon having a top surface and a bottom surface, wherein a distance between the top surface and the bottom surface defines a thickness of the body;

a first side edge and a second side edge formed on the body, wherein a distance between the first side edge and the second side edge defines a width of the body;

a deformable first slot formed in the first side edge and extending into the body in the direction of the width of the body; and

a deformable second slot formed in the second side edge and extending into the body in the direction of the width of the body.

2. The isolator of claim 1, wherein the first groove extends parallel to the top and bottom surfaces toward a center of the isolator, and wherein the second groove extends parallel to the top and bottom surfaces toward the center of the isolator.

3. The isolator of claim 2, wherein the first groove extends into the body at least half way to the center of the isolator, and wherein the second groove extends into the body at least half way to the center of the isolator.

4. The isolator of claim 1, wherein the body is formed of a dielectric material.

5. The separator of claim 4, wherein the dielectric material is void-free or foamed polyethylene or void-free or foamed Fluorinated Ethylene Propylene (FEP).

6. The separator of any of claims 1, 2, 3, 4, or 5, wherein the thickness of the body is between 9 and 18 mils.

7. The separator of any of claims 1, 2, 3, 4, or 5, wherein the width of the body is between 90 and 130 mils.

8. The isolator of any one of claims 1, 2, 3, 4, or 5, wherein the top surface includes a first recessed area proximate a midpoint between the first side edge and the second side edge, and wherein the bottom surface includes a second recessed area proximate a midpoint between the first side edge and the second side edge.

9. The isolator according to claim 8, wherein said first recessed area is a first v-shaped notch, and wherein said second recessed area is a second v-shaped notch.

10. The isolator of claim 9, wherein the first v-notch is formed by a first angled surface intersecting a second angled surface, and wherein the first angled surface meets the second angled surface at an angle of approximately ninety degrees, and wherein the second v-notch is formed by a third angled surface intersecting a fourth angled surface, and wherein the third angled surface meets the fourth angled surface at an angle of approximately ninety degrees.

11. The isolator of any one of claims 1, 2, 3, 4, or 5, wherein the top surface is formed from first and second planar surfaces and a first step between the first and second planar surfaces, and wherein the bottom surface is formed from third and fourth planar surfaces and a second step between the third and fourth planar surfaces.

12. A method of forming a twisted pair cable, comprising:

providing an isolator, the isolator comprising:

a first slot formed in the first side edge and extending into the main body in the direction of the width of the main body; and

a second groove formed in the second side edge and extending into the main body in the direction of the width of the main body;

feeding the first twisted pair, the second twisted pair, the third twisted pair, and the fourth twisted pair to a cable assembly area;

feeding the isolator to the cable assembly area;

inserting a first wedge into the first groove and opening the first groove as the isolator enters the cable assembly area, thereby causing deformation of the flat ribbon;

inserting a second wedge into the second groove and opening the second groove as the isolator enters the cable assembly area, thereby causing deformation of the flat ribbon;

Placing the first twisted pair into an open first slot of the separator;

placing the second twisted pair adjacent to the top surface of the isolator;

placing the third twisted pair into an open second slot of the separator;

placing the fourth twisted pair adjacent to the bottom surface of the separator; and

extruding an outer jacket over the separator and the first twisted pair, the second twisted pair, the third twisted pair, and the fourth twisted pair.

13. The method of claim 12, further comprising:

core twist is applied to the separator and the first, second, third and fourth twisted pairs prior to the extruding step.

14. The method of claim 12, further comprising:

the separator and the first, second, third and fourth twisted pairs are surrounded by a shielding layer prior to the extruding step.

15. The method of claim 12, further comprising:

imparting core twist to the separator and the first, second, third and fourth twisted pairs; and

16. A cable, comprising:

a first conductor; a first insulating material surrounding the first conductor to form a first insulating conductor; a second conductor; and a second insulating material surrounding the second conductor to form a second insulated conductor, wherein the first and second insulated conductors are twisted with each other to form a first twisted pair;

a third conductor; a third insulating material surrounding the third conductor to form a third insulated conductor; a fourth conductor; and a fourth insulating material surrounding the fourth conductor to form a fourth insulated conductor, wherein the third and fourth insulated conductors are stranded with each other to form a second twisted pair;

a fifth conductor; a fifth insulating material surrounding the fifth conductor to form a fifth insulated conductor; a sixth conductor; and a sixth insulating material surrounding the sixth conductor to form a sixth insulated conductor, wherein the fifth insulated conductor and the sixth insulated conductor are twisted with each other to form a third twisted pair;

A seventh conductor; a seventh insulating material surrounding the seventh conductor to form a seventh insulating conductor; an eighth conductor; and an eighth insulating material surrounding the eighth conductor to form an eighth insulated conductor, wherein the seventh insulated conductor and the eighth insulated conductor are twisted with each other to form a fourth twisted pair;

an isolator separating the first twisted pair from the second twisted pair, the third twisted pair and the fourth twisted pair, separating the second twisted pair from the third twisted pair and the fourth twisted pair, and also separating the third twisted pair from the fourth twisted pair, wherein the isolator comprises:

A deformable second slot formed in the second side edge and extending into the body in the direction of the width of the body, wherein the separator has a closed first notch formed on the top surface thereof and the first twisted pair is adjacent the top surface, and the separator has a closed second notch on the bottom surface thereof and the third twisted pair is adjacent the bottom surface; and

a jacket surrounding the separator, the first twisted pair, the second twisted pair, the third twisted pair, and the fourth twisted pair.

17. The cable of claim 16, wherein the closed first notch is formed by an abutment of a first inclined surface in the top surface with a second inclined surface in the top surface, and wherein the closed second notch is formed by an abutment of a third inclined surface in the bottom surface with a fourth inclined surface in the bottom surface.

18. The cable of claim 16, further comprising:

a shielding layer, wherein the shielding layer surrounds the separator and the first, second, third, and fourth twisted pairs, and the shielding layer resides within the jacket.

19. The cable of claim 16, wherein the separator and the first, second, third, and fourth twisted pairs have core twist within an outer jacket.

20. The cable of claim 16, further comprising:

a shielding layer, wherein the shielding layer surrounds the separator and the first, second, third, and fourth twisted pairs, and the shielding layer resides within the jacket, and wherein the separator and the first, second, third, and fourth twisted pairs have core twist within the shielding layer.