CN113646852A

CN113646852A - Low cost extrudable isolator made from slit tape

Info

Publication number: CN113646852A
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: 2021-11-12
Anticipated expiration: 2040-03-30
Also published as: CN113646852B; MX2021012306A; EP3953951A1; WO2020210075A1

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 separator at least half way. A second slot is formed in the second side edge and extends toward the center of the separator at least half way. The first and second wedges open the first and second slots during cable manufacture. The first and second twisted wires are inserted into the opened first and second slots, 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 a flat separator tape while providing the internal crosstalk performance of the isolator.

Description

Low cost extrudable isolator made from slit tape

Technical Field

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

Background

With the growing use of computers for homes and offices, there has developed a need for cables that can be used to connect peripheral equipment to a computer 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 various enhanced operating performance criteria, such as a reduction in internal and external crosstalk when the cable is in high cable density applications (e.g., routing alongside other cables).

Fig. 1 and 2 show a typical shielded twisted pair cable 1 and the twisting scheme employed for the wires of the four twisted pairs (first twisted pair a, second twisted pair B, third twisted pair C and fourth twisted pair D). Dielectric isolator 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 separators 3 may also be considered as slots, star separators or plus separators.

Twisted pairs A, B, C and D in combination with separator 3 may be twisted in the direction of arrow 5 (e.g., opposite to the twist direction of twisted pairs A, B, C and D) to form a stranded core. The strand core is surrounded by a shield layer 7. The shield layer 7 may be formed from a conductive foil and the edges of the foil may partially overlap at the region 9. A dielectric outer sheath 11 then surrounds the shield 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. Fourth twisted pair D includes seventh insulated conductor 25 and eighth insulated conductor 27.

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

Each of twisted pairs A, B, C and D has a fixed twist lay w, x, y, z, respectively. Each of the twist lays w, x, y, z is different from the twist lays of the other twisted pairs. As is known in the art, such an arrangement helps to 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 twisted pairs A, B, C and D has a unique fixed twist lay slightly greater or less than 0.500 inches. Table 1 below summarizes the lay lengths of twisted pairs A, B, C and D.

TABLE 1

Twisted pair	Lay length	Minimum strand lengthDegree of rotation	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 isolator 3 is a rather expensive component of the cable core. Furthermore, the separator 3 is an extruded element with four projecting fins and is not well wound on a reel, for example, there are many air gaps in the wound separator 3. Therefore, a shorter length of separator 3 can be wound onto a reel of a given size.

Extruding a flat separator strip is relatively less expensive than a plus sign isolator 3. Moreover, the extruded flat separator tape wound well on the reel with much less air space. Thus, there may be a substantially longer flat separator strip on a reel of the same given size.

However, there are significant disadvantages to flat separator belts. The flat separator strip separates only two of the twisted pairs from the other two, for example, twisted pairs a and C from twisted pairs B and D. Therefore, the flat separator tape is inferior in reducing internal crosstalk, compared to the separator 3 in fig. 1 and 2.

Applicants have invented a new separator that can be extruded as a flat strip with a slit formed in its thickness. Alternatively, the new separator may be extruded as a flat strip, and the slit 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 isolator, one on each lateral side of the new isolator. The new separator may be wound onto a reel in the same manner as conventional flat separator tape. Thus, the new isolator does not include much air within the windings on the spool and a longer new isolator can be wound on a spool of the same given size as compared to the old isolator 3 of fig. 1-2.

When manufacturing the cable, a new isolator is fed from a reel to the cable assembly area. In the cable assembly area, the wedge opens the slit. The first twisted pair is inserted in a first wedge in the open wedge, the second twisted pair is inserted in a second slit in the open slit, the third twisted pair is placed on top of the new isolator, and the fourth twisted pair is placed under the new isolator. Next, an optional shield or core layer surrounds the cable core, and finally an outer jacket is extruded over the cable core.

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

These and other objects are achieved by an isolator for a twisted pair cable, 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 body in the direction of the width of the separator; and a second groove formed in the second side edge and extending into the body in the direction of the width of the separator.

These and other objects are also achieved by a method of forming a twisted pair cable, 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 spacer; 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 body in a direction of a width of the separator; and a second groove formed in the second side edge and extending into the 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 a first wedge into and opening the first slot as the isolator passes through the cable assembly area; inserting a second wedge into and opening the second slot 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 a third twisted pair in an open second slot of the isolator; placing a fourth twisted pair adjacent to a bottom surface of the separator; and extruding an outer jacket over the separator and the first, second, third, and fourth twisted pairs.

These and other objects are furthermore achieved by a cable comprising: a first conductor; a first insulating material surrounding the first conductor to form a first insulated 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 to 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; a separator 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 a fourth twisted pair, and also separating the third twisted pair from the fourth twisted pair, wherein the separator has a closed first notch formed on a top surface thereof and the first twisted pair is adjacent the top surface, and a closed second notch on a 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.

Further scope of applicability of the present invention will become apparent from the detailed description given 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 and the detailed description given below, which are given by way of illustration only, and thus are not limitative of the present invention, 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 invention;

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

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

figure 6 is a block diagram of a machine for producing twisted pair cable using the isolators of figures 3-5;

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

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

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

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

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

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

FIG. 12 is a cross-sectional view of the isolator of FIG. 11 after assembly of the units by the cables;

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

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

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

fig. 16 is a perspective view of a portion of the sheet of the separator produced by the 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 drawings, the thickness of some lines, layers, components, elements or features may be exaggerated for clarity. Broken 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 should 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 interpreted 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., another element, 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, for example, "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 references to a structure or feature that is disposed "adjacent" another feature may have portions that overlap or underlie the adjacent feature.

For convenience in description, spatially relative terms, such as "under," "below," "lower," "above," "upper," "lateral," "left," "right," and the like, may be used herein 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 the 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. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the descriptors of relative spatial relationships used herein interpreted accordingly.

Fig. 3 is a block diagram of the spool or reel 31 of the wound isolator 33A according to the first embodiment of the present invention. Isolator 33A is fed into cable assembly area 35 and may pass over one or more powered or idle wheels or rollers 37. More description will be given regarding the cable assembly area 35 with respect to fig. 6.

Fig. 4 is a sectional view of the separator 33A taken along the line IV-IV in fig. 3. Isolator 33A includes a body 39 formed as an elongated strip having a top surface 41 and a bottom surface 43. A first distance D1 exists between top surface 41 and bottom surface 43 and defines the thickness of spacer 33A. A first side edge 45 and a second side edge 47 are formed on the body 39. A second distance D2 exists between first side edge 45 and second side edge 47 and defines the width of 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 isolator 33A that runs along the length of the isolator 33A. The first groove 49 extends into the body 39 at least half the 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 into 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 a gas bubble, such as an air bubble, is purposefully 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 isolator 33A.

In a preferred embodiment, the thickness, represented by distance Dl, is between 9 and 18 mils, such as between 10 and 15 mils, or about 12 mils. 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 a twisted pair cable 65 using the isolator 33A of fig. 3-5. In addition to the elements of fig. 3, the machine 63 also 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 the twisted pair cable 65, the first twisted pair a, the second twisted pair B, the third twisted pair C and the fourth twisted pair D are fed into the cable assembly area 35 along with the 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 spaced apart second wedge 77 is located adjacent second side edge 47 of 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 obtains the configuration shown in fig. 5 as the first wedge member 75 and the second wedge member 77 open the first groove 49 and the second groove 51. In other words, the portion of the isolator 33A to the right (upstream) of the first wedge member 75 and the second wedge member 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 wedge member 75 and the second wedge member 77 in fig. 6A has the cross section of fig. 5. The body 39 of the separator 33A may undergo permanent elastic deformation such as compression and elongation when the first wedge member 75 and the second wedge member 77 open the first groove 49 and the second groove 51. In other words, the material forming the 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 and

second legs

55, 57 is approximately ninety degrees and the angle between the third and

fourth legs

59, 61 is approximately ninety degrees. Opening the first and

second slots

49, 51 results in a first arch 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. Also, 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 region 35, the first twisted pair a is disposed in the open first slot 49, the second twisted pair B is disposed adjacent the top surface 41 in the first arcuate portion 41A, the third twisted pair C is disposed in the open second slot 51, and the fourth twisted pair D is disposed adjacent the bottom surface 43 in the second arcuate portion 43A. Preferably, the cable assembly area 35 twists the assembled isolator 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. Inside the shielding unit 81, the shielding layer 7 surrounds and surrounds the twisted core 79. The shielding layer 7 may further comprise an overlapping portion 9 as shown in fig. 1-2 to form a shielding stranded core 85. The shield layer 7 may be formed by 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 polyester film or biaxially oriented polyethylene terephthalate, for example

The shielding stranded 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 shield layer 7 to form the twisted pair cable 65. The outer jacket 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.

The twisted pair cable 65 is typically passed through a cold water bath 88 to solidify the outer jacket 11 and then accumulated onto a spool 89. The machinery for making the twisted pair cable 65 is basically 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 a separator 33B according to a second embodiment. The separator 33B includes a body 39B formed as an elongated strip having a top surface 41B and a bottom surface 43B. A first distance D3 exists between top surface 41B and bottom surface 43B and defines the thickness of spacer 33B. A first side edge 45B and a second side edge 47B are formed on the main body 39B. Second distance D4 exists between first side edge 45B and second side edge 47B and defines the width of separator 33B.

A first slot 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 parallel to the top surface 41B and the bottom surface 43B toward the center 53B of the separator 33B. The first slot 49B extends into the body 39B at least half the 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 extends along the entire length of the isolator 33B. The first slot 49B creates a first leg 55B and a second leg 57B.

A second slot 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 parallel to the top surface 41B and the bottom surface 43B toward the center 53B of the separator 33B. The second slot 51B extends into the body 39B at least half the 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 extends 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 about 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 point of curvature 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 curves, like the ninety degree angles 103 and 105 illustrated in fig. 8. However, FIG. 8 still illustrates the elongated deformation in

regions

107 and 109 when isolator 33B is opened by first wedge member 75 and second wedge member 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 a separator 33C according to a third embodiment. The isolator 33C includes a body 39C formed as an elongated strip having a top surface 41C and a bottom surface 43C. A first distance D1 exists between top surface 41C and bottom surface 43C and defines the thickness of spacer 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 first side edge 45C and second side edge 47C and defines the width of 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 parallel to the top surface 41C and the bottom surface 43C toward the center 53C of the separator 33C. The first groove 49C extends into the body 39C at least half the 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 extends along the entire length of the isolator 33C. The first slot 49C creates a first leg 55C and a second leg 57C.

A second slot 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 parallel to the top surface 41C and the bottom surface 43C toward the center 53C of the separator 33C. The second groove 51C extends into the body 39C at least half the 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 extends 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-notch and the second recessed area 109 is a second v-notch. The first v-shaped notch is formed by the intersection of the first inclined surface 111 and the second inclined surface 113, wherein the intersection of the first inclined surface 111 and the second inclined surface 113 is at an angle of about forty-five degrees. A second v-shaped notch is formed by the intersection of the third inclined surface 115 and the fourth inclined surface 117, wherein the third inclined surface 115 and the fourth inclined surface 117 intersect at an angle of approximately forty-five degrees.

The first and second v-shaped notches provide a natural point of curvature when the first and

second grooves

49C and 51C are opened by the first and second wedge-shaped

members

75 and 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 sectional view of a separator 33D according to a fourth embodiment. The separator 33D includes a body 39D formed as an elongated strip having a top surface 41D and a bottom surface 43D. A first distance D1 exists between top surface 41D and bottom surface 43D and defines the thickness of spacer 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 first side edge 45D and second side edge 47D and defines the width of 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 into 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 extends 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 to the top surface 41D and the bottom surface 43D. The second slot 51D extends into the body 39D at least half way into 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 extends 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 top surface 41D includes a first recessed area 119 proximate the midpoint between first side edge 45D and second side edge 47D, and bottom surface 43D includes a second recessed area 121 proximate the midpoint between first side edge 45D and 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-notch is formed by the intersection of a first inclined surface 123 and a second inclined surface 125, wherein the first inclined surface 123 and the second inclined surface 125 intersect at an angle of approximately ninety degrees. The second v-shaped notch is formed by the intersection of the third inclined surface 127 and the fourth inclined surface 129, wherein the third inclined surface 127 and the fourth inclined surface 129 intersect at an angle of approximately ninety degrees.

second grooves

49D, 51D are opened by the first and second wedge-shaped

members

75, 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 a twisted pair cable 65D. Twisted-pair cable 65D includes a first twisted pair 131. First twisted pair 131 includes a first insulated conductor 135 formed by first insulating material 135A surrounding first conductor 135B and a second insulated conductor 137 formed by second insulating material 137A surrounding second conductor 137B. The first insulated conductor 135 and the second insulated conductor 137 are twisted with each other to form a first twisted pair 131.

The second twisted pair 139 includes a third insulated conductor 141 formed by a third insulating material surrounding a third conductor and a fourth insulated conductor 143 formed by a fourth insulating material surrounding a fourth conductor, wherein the third and fourth

insulated conductors

141, 143 are twisted with each other to form the second twisted pair 139.

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

The fourth twisted pair 151 includes a seventh insulated conductor 153 formed by a seventh insulating material surrounding the seventh conductor and an eighth insulated conductor 155 formed by an eighth insulating material surrounding the eighth conductor, 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, second, third, and fourth

twisted pairs

131, 139, 145, 151, respectively, may be the same as those listed in table 1 for 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 field, 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, each of the first through eighth conductors is a void-free copper wire of about twenty-three gauge size.

Similar to fig. 1, the cable cores of twisted pair cable 65D may be twisted in the direction of arrow 30 to form a core strand. In the illustrated embodiment, the direction 30 is opposite to the twist direction of the first, second, third and fourth

twisted pairs

131, 139, 145 and 151 and may provide advantages as discussed in assignee's U.S. patent 6,770,819, which is incorporated herein by reference. This is not a necessary feature, however, as the advantages of the present invention will still be clear where the direction 30 of the core strands is the same as the twist direction of the twisted pairs.

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. Isolator 33D also has a closed second notch on its bottom surface 43D and a third twisted pair 145 is adjacent 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 shield 7 surrounds the isolator 33D and the first, second, third and fourth

twisted pairs

131, 139, 145 and 151. The outer jacket 11 surrounds the shield 7, the isolator 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 shield layer 7 is optional and/or can be removed, especially if the cable is employed in an environment where alien crosstalk is not an issue, 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 (twisted 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 twist modulation and/or core strand modulation, as shown in 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 a hopper 167. The pellets may be formed of polyethylene or Fluorinated Ethylene Propylene (FEP) or other such material. Extruder 169 heats pellets 165 into a slurry. The slurry may be extruded through the extrusion die 171 in a void-free form or with a blowing agent. The sheet 163 of separator 33D may pass over one or more powered or idle rollers 162 and then be accumulated 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, before being stored on reel 164. The construction of the machine 161, apart from that of the extrusion die 171, substantially corresponds to that of known machines for producing sheets of separator "strips".

Fig. 15 is a close-up view of the circled portion XV of 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 projections to create first and

second slots

49D, 51D, first and

second legs

55D, 57D, third and

fourth legs

59D, 61D, and first and second recessed

areas

119, 121. In practice, the sheet 163 of spacers 33D may include twenty to twenty-five spacers 33D arranged side-by-side.

Fig. 16 is a perspective view of a part 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 a portion of the separator 33B on each of the left and right sides. The arrow 173 indicates the point at which the sheet 163 of the separator 33D is cut for forming the individual separator 33D. The cutting is typically performed by the blade or laser as the sheet is driven through the blade or laser, and individual isolators 33D are accumulated on the separator reel 31, as shown in fig. 3 and 6, for shipment to a customer, e.g., a cable manufacturer. As previously mentioned, the extrusion and cutting process may be performed in the same manner as previously performed for the manufacture of separator belts, 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 use a blade or laser to cut all of the features of separator 33D (first and

second slots

49D and 51D and first and second recessed areas 119 and 121) into separator 33D as sheet 163 and/or individual separator 33D is driven past 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 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 slot formed in the first side edge and extending into the body in a direction of the width of the separator; and

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

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

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

4. A spacer as defined in any of claims 1, 2 or 3, wherein the body is formed of a dielectric material.

5. The isolator of claim 4, wherein the dielectric material is a void-free or foamed polyethylene or a 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 separator is between 9 and 18 mils.

7. The separator of any of claims 1, 2, 3, 4, 5, or 6, wherein the width of the separator is between 90 and 130 mils.

8. The separator of any of claims 1, 2, 3, 4, 5, 6, or 7, wherein the top surface comprises a first recessed area proximate a midpoint between the first side edge and the second side edge, and wherein the bottom surface comprises a second recessed area proximate a midpoint between the first side edge and the second side edge.

9. The isolator of claim 8, wherein the first recessed area is a first v-shaped notch, and wherein the second recessed area is a second v-shaped notch.

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

11. The isolator as in any one of claims 1, 2, 3, 4, 5, 6, or 7, wherein the top surface is formed by first and second planar surfaces and a first step between the first and second planar surfaces, and wherein the bottom surface is formed by 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 second groove formed in the second side edge and extending into the body in the direction of the 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 the isolator to the cable assembly area;

inserting a first wedge into the first slot and opening the first slot as the isolator enters the cable assembly area;

inserting a second wedge into and opening the second slot as the isolator enters the cable assembly area;

placing the first twisted pair into an open first slot of the isolator;

placing the second twisted pair near the top surface of the isolator;

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

placing the fourth twisted pair near the bottom surface of the separator; and

extruding an outer jacket over the isolator and the first, second, third, and fourth twisted pairs.

13. The method of claim 12, further comprising:

applying core twist 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:

surrounding the separator and the first, second, third and fourth twisted pairs with a shielding layer prior to the extruding step.

15. The method of claim 12, further comprising:

applying core twist to the isolator and the first, second, third and fourth twisted pairs; and

16. An electrical cable, comprising:

a first conductor; a first insulating material surrounding the first conductor to form a first insulated 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 insulated 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;

a separator 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 separator has a closed first notch formed on a top surface thereof and the first twisted pair is adjacent the top surface, and the separator has a closed second notch on a bottom surface thereof and the third twisted pair is adjacent the bottom surface; and

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

17. The cable according to claim 16, wherein the closed first notch is formed by 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 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 shield, wherein the shield surrounds the isolator and the first, second, third, and fourth twisted pairs, and the shield resides within the jacket.

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

20. The cable of claim 16, further comprising:

a shield, wherein the shield surrounds the isolator and the first, second, third, and fourth twisted pairs and the shield resides within the jacket, and wherein the isolator and the first, second, third, and fourth twisted pairs have a core twist within the shield.