United States Patent (19)
`Hubis et al.
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`(54)
`(75)
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`(73)
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`21)
`22
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`52
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`TWSTED PAR DATABUS CABLE
`Inventors: Paul E. Hubis, Newark, Del.: Kim E.
`Ritchie, Elkton, Md.
`Assignee: W. L. Gore & Associates, Inc.,
`Newark, Del.
`Appl. No.: 909,895
`Filed:
`Jul. 7, 1992
`int. Cl’............................................... H01B 7/34
`U.S.C. ........................................ 174/36; 156/51;
`174/34; 174/102 R; 174/113 R; 174/117 F
`Field of Search ................. 174/36, 32, 34, 17 F,
`174/102 R, 113 R; 156/51
`References Cited
`U.S. PATENT DOCUMENTS
`1,654,074 12/1927 Fondiller ............................... 178/45
`2,787,653 4/1957 Ormerod ......................... 174/117 R
`3,025,656 3/1962 Cook ................................. 174/34 X
`3,187,495 6/1965 Christian, Jr. .....
`... 174/34 X
`3,320,350 5/1967 Corrall et al. ......................... 174/34
`3,382,314 5/1968 Nordblad.......
`... 174/34
`3,448,569 6/1969 Brown et al. ........................... 57/15
`4,041,237 8/1977 Stine et al. ............................ 174/36
`
`US005283390A
`Patent Number:
`Date of Patent:
`
`11
`45)
`
`5,283,390
`Feb. 1, 1994
`
`4,096,346 6/1978 Stine et al. ............................ 174/36
`4,697,051 9/1987 Beggs et al. .
`174/36X
`4,860,343 8/1989 Zetena, Jr. ..
`. 174/34 X
`5,015,800 5/1991 Vaupotic et al.
`174/34
`5,142,100 8/1992 Vaupotic et al. ..................... 174/24
`FOREIGN PATENT DOCUMENTS
`263717 3/1990 France .................................. 74/36
`8202627 1/1984 Netherlands .......................... 174/36
`999545 7/1965 United Kingdom.................. 174/36
`9210841 6/1992 World Int. Prop. O. .
`Primary Examiner-Morris H. Nimmo
`Attorney, Agent, or Firm-Gary A. Samuels
`57
`ABSTRACT
`A twisted pair data bus cable is provided which is small,
`lightweight and flexible.
`The cable consists of a pair of insulated conductors
`twisted about one another, which has sections of the
`cable surrounded by metallic shielding, in which the
`sections surrounded by metallic shielding having a
`thicker insulation cross section than the sections not
`surrounded by metallic shielding.
`
`2 Claims, 1 Drawing Sheet
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`U.S. Patent
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`Feb. 1, 1994
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`5,283,390
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`U.S. Patent
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`Feb, 1, 1994
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`5,283,390
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`FIG. |
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`Page 2
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`CommsScope Exhibit 1027
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`

`

`1
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`TWSTED PAR DATABUS CABLE
`
`5
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`O
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`15
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`FIELD OF THE INVENTION
`This invention relates to electrical cables, and in par
`ticular to a twisted pair data bus cable that has areas of
`shielding and areas of non-shielding; and to a process
`for making the cable.
`BACKGROUND OF THE INVENTION
`In electrical systems where signals are transferred
`from one instrument to another, a data transfer wiring
`system known as a data bus wiring system may be used.
`Those complex systems depend on electronic instru
`ments to determine a condition or a set of conditions,
`and then transmit information or receive signals about
`the information over electronic wiring. Such a system is
`found in "fly-by-wire' aircraft systems where instru
`ments detect various conditions of the aircraft and pro
`cess the information to control the flight of the aircraft.
`20
`To transfer the various signals from one instrument to
`another, a data bus wiring system is used.
`A twisted pair of insulated conductors can be used as
`the data bus. However, while some areas along the
`length of the data bus must be unshielded so that "stub'
`cables to and from the instruments can be coupled to the
`bus, other areas along the bus must be shielded to pre
`vent electrical signals from being radiated or from being
`subjected to outside noise. However, shielding causes a
`change in the size, weight, flexibility and electrical
`30
`properties of the twisted pair data bus. For example,
`shielding lowers the impedance in that area of the cable
`and adversely affects performance of the system.
`SUMMARY OF THE INVENTION
`35
`In this invention, a twisted pair cable data bus is pro
`vided which is small, lightweight, flexible and has sub
`stantially the same impedance in shielded areas as in
`unshielded areas.
`More specifically, this invention is a continuous cable
`consisting of a pair of insulated conductors twisted
`about one another, which has sections of the cable sur
`rounded by metallic shielding, in which the sections
`surrounded by metallic shielding having a thicker insu
`lation cross section than the sections not surrounded by
`45
`metallic shielding, the thickness of the thicker insulation
`being such that the impedance of the sections sur
`rounded by metallic shielding is substantially the same
`as the section not surrounded by metallic shielding.
`BRIEF DESCRIPTION OF THE DRAWING
`FIG. 1 depicts a cross section of a portion of the cable
`of the invention that contains shielding and added insu
`lation.
`FIG. 2 depicts a cross section of the cable of the
`invention that has no shielding or extra insulation.
`FIG. 3 depicts a perspective view of a twisted pair
`that has had extra insulation and shielding added in
`selected sections.
`DETAILED DESCRIPTION OF THE
`INVENTION
`Referring to the drawings, a cross section of a cable
`of the invention containing a twisted pair of conductors
`is depicted in FIGS. 1 and 2. FIG. 1 depicts a cross
`65
`section of a portion of the cable that is shielded. FIG. 2
`depicts an unshielded cross section. In both Figures, the
`conductor wire 1 is surrounded by insulation 2 to form
`
`5,283,390
`2
`a primary insulated wire. As shown in FIG. 1, an addi
`tional layer or layers of insulation 3 are placed over
`insulation 2 at areas of the cable that will be shielded.
`Thus the cable will have areas of unequal diameter.
`Then two such insulated conductors are twisted to
`gether in any conventional manner, taking care to en
`sure that sections of each insulated wire that have added
`insulation are matched and twisted together. This is
`shown in FIG. 3 where section. A contains only wire 1
`and insulation 2 and where section B's cross section is
`larger due to presence of added insulation. As shown in
`FIG. 1, the spacing between the insulated conductors of
`the pair may be less than the diameter of a single insu
`lated conductor, due to possible densifying of the insu
`lating at the area of contact between the insulated con
`ductors as a result of having been twisted together,
`Next, the twisted pair of primary insulated wires is
`bonded by heating until a bond is formed. Shielding 4 is
`then placed over the bonded twisted pair and is cut
`away from the areas that do not have added insulation.
`Lastly a protective jacket 5 is placed over the
`shielded area.
`The conductor wire 1 can be any electrical conduc
`tor, such as copper, silver or nickel plated copper, stain
`less steel, copper alloy, silver, nickel or beryllium cop
`per.
`Insulation 2 can be any insulation of low dielectric,
`but preferably is sintered expanded, porous polytetra
`fluoroethylene. Preferably, also it will be a tape that is
`helically wrapped around the conductive wire 1.
`The additional layers of insulation 3 can be additional
`layers of expanded, porous polytetrafluoroethylene that
`may be strengthened by sintering or applying a skin of
`a fluorinated thermoplastic polymer, or both. Several
`layers of such varying tape constructions can be applied
`depending on the electrical properties desired.
`The amount of thickness of extra insulation 3 that is
`added to selected sections of the cable is an amount
`necessary to maintain substantially the same impedance
`from shielded sections to unshielded sections. Thus the
`usual effect of lower impedance that is imparted by the
`shield is counteracted by using a greater thickness of
`insulation under the shield since added insulation in
`creases the impedance. It is recognized that the extra
`amount used will depend both on the type of shielding
`and the dielectric of the insulation used.
`The shielding 4 can be any metallic shielding, such as
`braided metal, served metal wire or served metal foil.
`An example of braided metal or served metal is silver
`plated copper. An example of a served foil is a foil of
`expanded, porous polytetrafluoroethylene containing a
`thin layer of aluminum. Preferably, the shielding 4 is
`braided tin-plated copper. The shielding can be applied
`by a braiding or serving machine.
`The jacketing 5 can be any protective plastic layer
`such as, Teflon TPFE resin, or a thermoplastic fluoro
`polymer.
`By this procedure, a continuous cable is obtained by
`"continuous” is meant that the cable is unspliced and
`unbroken.
`In a typical cable assembly, the following characteris
`tics of the cable were obtained:
`
`25
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`50
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`55
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`Characteristic
`Impedance
`
`Shielded
`Unshielded
`130 ohms .5% <2% change from
`unshielded
`impedance
`
`

`

`3
`-continued
`Shielded
`Unshielded
`Characteristic
`>77%
`Velocity of Propagation >78%
`6.6 dB/1000 feet
`Attenuation
`6.1 dB/1000 feet
`0.140 inch
`Primary Wire Diameter 0.085 inch
`0.250 inch nominal
`Twisted Pair diameter
`0.16S inch
`0.290 inch nominal
`Overal Diameter
`0.165 inch
`Weight
`14.7 lbs./000 feet 47.0 lbs./000 feet
`Shield Coverage
`85%
`Stiffness
`2.2 pounds
`(pounds of force to
`deflect a ten inch
`sample one inch on
`an instron machine)
`
`10
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`5,283,390
`4.
`2. A process for preparing a continuous electrical
`cable consisting of a pair of insulated conductors
`twisted about one another, which has sections of the
`cable surrounded by metallic shielding, and which has
`sections of the cable not surrounded by metallic shield
`ing, in which the sections surrounded by metallic shield
`ing have a thicker insulation cross-section than the sec
`tions not surrounded by metallic shielding, the thickness
`of the thicker insulation being such that the impedance
`of the sections surrounded by metallic shielding is sub
`stantially the same as the sections not surrounded by
`metallic shielding, which comprises, in sequence:
`(a) applying insulation to conductor wire;
`(b) applying additional insulation to certain sections
`of the insulated conductor wire;
`(c) twisting a first and second such insulated conduc
`tor wires around each other, such that the sections
`of additional insulation of the first insulated con
`ductor wire are twisted with corresponding sec
`tions of additional of the second insulated conduc
`tor wire;
`(d) applying metallic shielding over said first and
`second twisted insulated conductors at said certain
`sections of additional insulation; and
`(e) applying protective jacketing over said metallic
`shielding.
`
`15
`We claim:
`1. A continuous electrical cable consisting of a pair of
`insulated conductors twisted about one another, which
`has sections of the cable surrounded by metallic shield
`ing, and which has sections of the cable not surrounded
`20
`by metallic shielding, in which the sections surrounded
`by metallic shielding have a thicker insulation cross-sec
`tion than the sections not surrounded by metallic shield
`ing, the thickness of the thicker insulation being such
`that the impedance of the sections surrounded by metal
`25
`lic shielding is substantially the same as the sections not
`surrounded by metallic shielding.
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`is
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`30
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`35
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`45
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`SO
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`55
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`65
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