Jacket and cord having circular and non-circular portions, and method for producing the same

A cord has a jacket for containing wires. The jacket has a plurality of circular portions and a plurality of non-circular portions alternating with each other. The circular portions are substantially circular, and the non-circular portions are substantially non-circular, and may be in the shape of a "C" or "U". The "C" or "U" shape maintains the wires in a predetermined order. A method for forming cord includes alternately: (a) extruding a circular portion having a cross section that is substantially circular around a plurality of wires; and (b) extruding a non-circular portion having a cross section that is substantially non-circular around the plurality of wires. The extrusion is continuous, so that the non-circular portion is adjacent to the circular portion. The non-circular portion may be opened so that the conductors are arranged substantially in a line.

FIELD OF THE INVENTION 
The present invention relates to the field of telecommunications generally, 
and more specifically to cords for data and voice circuits. 
DESCRIPTION OF THE RELATED ART 
Cords capable of carrying voice and data are well known. 
For example, Lucent Technologies, Inc. manufactures data grade 1074 cordage 
having 24 gauge, stranded copper conductors insulated with high density 
polyethylene. Typically, each conductor has a different insulation color, 
so the conductors may be distinguished from each other. The insulated 
conductors are tightly twisted into individual pairs. These cords are 
available in 1-, 2-, 3-, and 4-pair sizes. In the cords having more than 
one pair of conductors, the pairs are twisted about each other. The pairs 
are then jacketed with a polyvinyl chloride (PVC) jacket. 
To use the cords, a connector, such as an 8-pin modular plug, is attached 
to an end of the cord. Because the conductors are twisted within pairs, 
and the pairs are twisted about each other, a visual identification has 
been required to determine which colored conductor should be attached to 
each pin of the connector. 
A substantially flat cord for data and voice has been designed, in which 
the pairs are arranged in a fixed order within the cord. Because the order 
is fixed, a visual inspection is not needed to determine which conductor 
should be connected to each pin of the connector. The flat cord, however, 
has disadvantages. Because the pairs of conductors are not twisted about 
each other, the electrical performance of the flat cord is not the same as 
the conventional twisted pair cord; the flat cord is likely to be noisier. 
Moreover, the area moment of inertia of the flat cord is much greater in 
one direction than the other, so the flat cord is only easily bent around 
one axis, namely the axis about which the moment of inertia is smaller. It 
is very difficult to bend the flat cord around the other axis. 
An improved cord is desired. 
SUMMARY OF THE INVENTION 
The present invention is a jacket for containing wires, having a plurality 
of circular portions and a plurality of non-circular portions alternating 
with each other. The circular portions are substantially circular, and the 
non-circular portions are substantially non-circular. 
According to another aspect of the invention, a cord includes a plurality 
of wires within a jacket having a plurality of circular portions and a 
plurality of non-circular portions alternating with each other. 
According to another aspect of the invention, a method for forming a jacket 
includes alternately: (a) forming a circular portion having a cross 
section that is substantially circular; and (b) forming a non-circular 
portion having a cross section that is substantially non-circular, the 
non-circular portion being adjacent to the circular portion. 
According to still another aspect of the invention, a method of forming a 
cord includes alternately (a) forming a circular jacket portion around a 
plurality of substantially circular wires, and (b) forming a non-circular 
substantially non-circular jacket portion around the plurality of wires, 
adjacent to the circular jacket portion.

DETAILED DESCRIPTION 
FIGS. 1-3 show an exemplary cord 100 having a jacket 111 according to the 
invention, for containing wires 112a-115b. The jacket 111 has a plurality 
of circular portions 120. Each circular portion 120 has a cross section 
that is substantially circular (as best seen in FIG. 3). The cross section 
of circular portion 120 is similar to the cross section of a conventional 
cord. 
The jacket 111 also has a plurality of non-circular portions 110. Each 
non-circular portion 110 has a cross section that is substantially 
non-circular. The cross section of each non-circular portion 110 of the 
jacket 111 is defined by a center 119. The non-circular portions 110 have 
an elongated cross section (best seen in FIGS. 2 and 3) which is folded or 
creased, so as to have the form of a letter "C" or "U." This shape may 
also be referred to as a crescent or horseshoe. A crease 118 is shown. A 
concavity 117 is produced. The circular portions 120 and non-circular 
portions 110 alternate with each other, as best seen in FIG. 1. FIG. 1 
also shows that at least one end portion 101 of the jacket is a 
non-circular portion 110. 
FIG. 3 shows that the end portion 101 is capable of being opened into an 
approximately flat configuration, as best seen in FIG. 3. With the end 
portion 101 in the flat open position, the plurality of wires 112a-115b 
housed within the jacket 111 have respective wire ends arranged 
substantially in a line. 
The above-described jacket 111 allows the plurality of wires to be arranged 
so that the ends of wires 112a-115b line up in a predetermined order 
within the line when the step of opening is performed. In the example, the 
predetermined order is blue 112a, light blue 112b orange 113a, light 
orange 113b, dark green 114a, green 114b, brown 115a, and light brown 
115b. This predetermined order matches an order in which a plurality of 
terminals are arranged in a flat connector (not shown) to which the ends 
of wires 112a-115b are to be connected. 
One of ordinary skill in the art recognizes that, so long as the wires 
within each individual pair of wires twists at a substantially constant 
number of millimeters per twist, and the pairs twist about each other at a 
substantially constant number of millimeters per twist, it is possible to 
calculate a least common multiple (LCM) distance at which the wires 
112a-115b are arranged within a non-circular section 110 in the same order 
as the ends of the wires in end portion 101. Similarly, one of ordinary 
skill in the art can readily determine the order in which the wires are 
arranged within jacket 111 at intermediate distances (less than the LCM 
distance), wherein the wires 112a-115b are arranged within a non-circular 
section 110 in a different order than the order shown in FIG. 3. 
One of the advantages of this configuration is that it allows a connector 
to be assembled to the cord 100 automatically, without visually inspecting 
the individual conductors 112a-115b. At any given non-circular portion 110 
along the cord 100, the order of the conductors 112a-115b may be 
determined based on the twist rates within the individual pairs, and the 
rates at which the pairs twist about each other. A machine can 
mechanically locate the concavity 117. The cable 100 can then be opened 
automatically at that non-circular portion 110 into the flattened position 
(FIG. 3). Because the order of the wires 112a-115b is already determined, 
a machine can attach the connector to the individual conductors 112a-115b 
without a visual identification of the colors by a human. 
According to another aspect of the exemplary embodiment, the circular 
portions 120 are substantially longer than the non-circular portions 110. 
One of ordinary skill in the art understands that the drawings are not to 
scale, and the distance between successive non-circular portions 120 may 
be much greater than the distance shown in FIG. 1. For example, the 
non-circular portions 110 may be about 2.5 centimeters (cm) or 1.0 inch 
long, and the circular portions 120 may be about 30 cm or 12 inches long. 
Other aspect ratios may also be used. 
The circular portions 120 have about the same area moment of inertia for 
bending in any direction, but the non-circular 110 portions have an area 
moment of inertia that varies, depending on the plane about which the 
non-circular portion 110 is bent. Any bend about a plane with a high area 
moment of inertia would require more bending force than is required to 
bend a conventional circular cord by the same angle. Because the circular 
portions 120 are much longer than the non-circular portions 110, the 
average area moment of inertia along the length of the cord 100 is 
approximately the same as the area moment of inertia of a conventional 
cord having only a circular cross section, no matter which plane the cord 
100 is bent about. Thus, cord 100 can be bent by a given angle in any 
direction without requiring substantially more effort than is required to 
bend a conventional cord having only circular cross sections by the same 
angle. 
FIGS. 5A and 5B show how the same jacket 111 may be used with any number of 
pairs of wires. For example, the cord end 201 in FIG. 5A includes two 
pairs of wires, in this case blue 212a, light blue 212b, orange 215a and 
light orange 215b. The cord end 301 of FIG. 5B has three pairs of wires, 
in this case, blue 312a, light blue 312b, orange 314a, light orange 314b, 
green 315a and light green 315b. One of ordinary skill in the art 
recognizes that these are only examples. The number of pairs of wires may 
vary, and the colors of each individual wire and pair of wires may also 
vary. 
The exemplary jacket and cord may be formed using the same materials that 
would be used for conventional cords. For example, the individual 
conductors may be coated with high density polyethylene. The jacket may be 
formed of a flame retardant PVC. Other materials may be used, as 
understood by one skilled in the art. 
FIG. 4A is a flow chart diagram of an exemplary method for forming the 
jacket 111. In this example, an extruder die having a movable portion is 
used. With the movable portion in a first position, a circular portion 120 
having a circular cross section is extruded. With the movable portion in a 
second position, a non-circular portion 110 having a non-circular cross 
section is extruded. 
At step 402, the wires are formed and twisted in a conventional manner. For 
example, the individual conductors may be passed through a ganged extruder 
to form the differently colored insulation on each conductor 112a-115b. 
Then the wires are twisted within pairs, and the pairs are twisted about 
each other. 
At step 404, a loop is initiated, which is repeated for each successive 
pair of portions 110, 120. This loop includes steps 404-412. 
At step 406, a circular portion 120 having a cross section that is 
substantially circular is extruded. 
At step 408, the movable portion of the die is moved from the first 
position to the second position for non-circular cross sections. 
At step 410, a non-circular portion 110 having a cross section that is 
substantially non-circular portion is extruded adjacent to the circular 
portion. 
At step 412, the movable portion of the die is moved from the second 
position back to the first position for extruding a portion having a 
circular cross section. 
After step 412, so long as additional length of cord is to be produced, 
execution returns to step 404, for repeating steps 406-412. The 
alternating portions of the extrusion are formed as one continuous jacket 
(as shown in FIG. 1). When N iterations have been performed (where N is an 
integer corresponding to the desired length of cord), the loop ends, and 
execution proceeds to FIG. 4B. 
FIG. 4B shows additional steps that are performed to connect the cord 
formed in FIG. 4A to a connector. At step 414, an end portion 101 is 
selected, and the non-circular portion 110 of the jacket 111 is opened to 
the substantially flat configuration. For example, a mechanical probe may 
move around the circumference of the end portion 101, until a radial 
movement of the probe detects the concavity 117. The cord may then be 
moved or rotated to a desired position for opening the non-circular 
portion 110. 
At step 416, having positioned the cord end 101 in the desired position, 
the positions of each conductor 112a-115b relative to the jacket can be 
calculated. Similarly, the order of the wire colors is determined 
analytically based on the length, as described above. Then an automated 
tool can individually locate and grip each wire. 
Depending on the length of any given cord, the order in which the wires 
line up at the cut end portion 101 may differ from the order in the 
connector. Thus, there are two significant cases to be considered: a first 
case in which the cord has a length at which the wire order repeats to 
match the connector order, and a second case in which the order of the 
wires at the cut (second) end differs from the order at the first end. 
In the first case, in which the order repeats, assuming that the order of 
the colors at the first end 101 of the cord matches the order of pins in 
the connector, the cut (second) end of the wire (not shown) has the colors 
in the mirror-image order from the first end 101 (for example, from left 
to right, wires 112a to 115b). To attach a connector, one can merely turn 
the connector upside down, and the order of the cord matches the order of 
the connector. 
In the second case, the positions of the wires are determined by analysis, 
and can be verified by a color recognition apparatus. For example, the 
order of the wires (from left to right) may be 112a, 112b, 114a, 114b, 
113a, 113b, 115a, 115b. Once the position of each wire is confirmed and 
the end portion of the jacket 111 is cut, the ends of two or more pairs 
may be manipulated to position the ends in the desired order. In this 
example, the second and third pairs are twisted about each other, so the 
positions are: 112a, 112b, 113a, 113b, 114a, 114b, 115a, 115b. 
At step 418, the wires are automatically connected to the connector in the 
desired predetermined order. 
FIG. 4B shows a variation of the exemplary method of FIG. 4A. This 
variation uses two different dies (not shown); a first die having a 
substantially circular cross section for extruding a circular jacket 
portion, and a second die having a substantially non-circular cross 
section for extruding a non-circular portion. Preferably, the second 
portion has a cross section in the shape of a "C" or "U." Nearly all of 
the steps are the same, except that steps 408 and 412 are replaced by 
steps 409 and 413, respectively. 
In step 409, the first die is removed and the second die is substituted 
therefor, for extruding a non-circular portion 110. 
In step 413, the second die is removed and the first die is substituted 
therefor, for extruding a circular portion 120. 
Steps 402 to 406, 410 are the same as described above with reference to 
FIG. 4A, and steps 414 to 418 are the same as described above with 
reference to FIG. 4B. For the sake of brevity, the descriptions of these 
steps are not repeated herein. 
Although the invention has been described in terms of exemplary 
embodiments, it is not limited thereto. Rather, the appended claim should 
be construed broadly, to include other variants and embodiments of the 
invention which may be made by those skilled in the art without departing 
from the scope and range of equivalents of the invention.