USOO7335837B2
`
`(12) United States Patent
`Pfeiler et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,335,837 B2
`Feb. 26, 2008
`
`(54) MULTI-LAYER, STRIP-TYPE SCREENING
`SHEET FOR ELECTRIC LINES AND
`ELECTRIC CABLE, IN PARTICULAR A
`DATA TRANSMISSION CABLE, EQUIPPED
`THEREWITH
`
`(75) Inventors: Christian Pfeiler, Nürnberg (DE):
`Andreas Wassmuth, Roth (DE); Jörg
`Weissbrod, Abenberg (DE); Brian
`George Race, Washington Tyne and
`Wear (GB)
`(73) Assignee: Draka Comteq Germany GmbH &
`Co. KG, Köln (DE)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`(21) Appl. No.: 11/217,666
`(22) Filed:
`Sep. 2, 2005
`
`(*) Notice:
`
`(65)
`
`Prior Publication Data
`US 2006/OO48961 A1
`Mar. 9, 2006
`
`Foreign Application Priority Data
`(30)
`Feb. 25, 2005 (DE) ...................... 10 2004 O42 626
`
`(51) Int. Cl.
`(2006.01)
`HOB II/06
`(52) U.S. Cl. .................. 174/36; 174/113 R; 174/113 C
`(58) Field of Classification Search ............ 174/113 R,
`174/113 C, 36
`See application file for complete search history.
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`
`5/1963 Volk ........................... 174f109
`3,090,825. A *
`3,312,774. A * 4, 1967 Drinko et al. ........ 174/120 SC
`4,788,088 A * 1 1/1988 Kohl ......................... 428, 34.5
`6,624,359 B2
`9/2003 Bahlmann et al.
`2003/0111241 A1
`6/2003 Bahlmann et al.
`2003/0217863 A1
`11/2003 Clark et al.
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`DE
`DE
`DE
`DE
`DE
`DE
`EP
`EP
`
`2 419 843. A 11, 1874
`1440919 A
`1, 1969
`93 1842O4. A
`3, 1994
`19809 808 A1
`10, 1998
`O 915 486 A1
`5, 1999
`19926 304 A1 12/2000
`102 05 937 A1
`8, 2002
`O 301 859 A2
`2, 1989
`O 915 486 A1
`5, 1999
`
`* cited by examiner
`Primary Examiner Chau N. Nguyen
`(74) Attorney, Agent, or Firm Browdy and Neimark,
`PLLC
`
`(57)
`
`ABSTRACT
`
`A multi-layer, strip-type screening sheet for electric lines
`comprises at least a Substrate layer of plastic material and at
`least one screening layer of electrically conductive material,
`in particular metal, which the substrate layer is lined with,
`the Screening layer being provided with spacing gaps that
`recur at longitudinal intervals for electrical interruption
`thereof in the longitudinal strip direction.
`
`2,796.463 A * 6/1957 Mallinckrodt ................ 178/45
`
`26 Claims, 8 Drawing Sheets
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`

`US 7,335,837 B2
`
`1.
`MULTI-LAYER, STRIP-TYPE SCREENING
`SHEET FOR ELECTRIC LINES AND
`ELECTRIC CABLE, IN PARTICULAR A
`DATA TRANSMISSION CABLE, EQUIPPED
`THEREWITH
`
`FIELD OF THE INVENTION
`
`The invention relates to a multi-layer, strip-type screening
`sheet for electric lines, in particular for multi-core data
`transmission cables, comprising at least one substrate layer
`of plastic material and at least one screening layer, con
`nected with the substrate layer, of electrically conductive
`material, in particular of metal. The invention further relates
`to an electric cable, in particular a data transmission cable,
`having at least one line, in particular several intertwisted
`pairs of lines, so-called twisted pairs, in which is used the
`screening sheet mentioned at the outset.
`
`10
`
`15
`
`BACKGROUND OF THE INVENTION
`
`2
`pieces of foil that lie between the spacing gaps, there will be
`no significant deterioration in the screening behaviour of the
`screening sheet.
`In keeping with a preferred embodiment of the invention,
`the spacing gaps recur periodically. The ratio that the
`spacing-gap width bears to the length of the pieces of foil
`between the spacing gaps preferably ranges between 1:5 and
`1:25, with typical lengths of the pieces of foil being in the
`range of 60 to 120 mm and typical widths of the spacing
`gaps being in the range of 5 to 10 mm. In practice, the
`corresponding geometric values must be chosen Such that no
`peaks of impedance or return loss, owing to the periodicity
`of the structure, will occur in the range of transmission
`frequency of the data transmission cable.
`In keeping with another preferred embodiment of the
`invention, Successive spacing gaps are arranged at a pref
`erably small, acute angle relative to the transverse direction
`of the strip. Upon alternating angular position, the pieces of
`foil between the spacing gaps will be trapezoidal. This
`configuration has the advantage that, with these strips of
`screening sheet being wound about their longitudinal axis
`for a tubular envelope to form, the spacing gaps run heli
`cally, which, upon interruption of the path of the current in
`the longitudinal direction, is accompanied with advantages
`in the screening behaviour as opposed to the gaps that are
`strictly rectangular in relation of the longitudinal direction of
`the strip.
`With the spacing gaps positioned in parallel at an angle to
`the transverse direction of the strip, the pieces of foil
`there-between have the form of a parallelogram. Upon
`application of the screening sheet in the longitudinal direc
`tion of the axis of the cable, this embodiment allows a gap
`to form that rotates in the way of a helix around the axis of
`the cable. Upon application of the sheet by a so-called
`banding system or when the cable is stranded, the acute
`angle of the spacing gaps relative to the transverse direction
`of the strip can be designed for compensation by the angle
`of Stranding, resulting in a cylindrical gap free of metal.
`An especially solid embodiment with high protection of
`the Susceptible metal screening layer results when the
`screening layer is placed between, and lined with, two
`substrate layers. The protective effect is still improved when
`these Substrate layers project over the longitudinal edges of
`the screening layer, there being united.
`The invention also relates to an electric cable and in
`particular a data transmission cable, with the external enve
`lope and/or an internal Supporting and separating structure
`being comprised of the screening sheet of one of the above
`mentioned designs. The external envelope, as an overall
`screen, protects the Surroundings against any energies that
`may radiate from the cable and it protects the transmission
`elements inside the cable, for example in the form of several
`twisted pairs, against irradiated interfering energy. In par
`ticular this aspect is of special importance in the application
`of the 10 GB-Ethernet on copper data transmission cables.
`The external envelope drastically reduces so-called cable
`crosstalk—also termed Alien-NEXT and Alien-EL-FEXT.
`Internal cable crosstalk between the individual twisted
`pairs is strictly reduced by the screening sheet being inte
`grated into an internal Supporting and separating structure,
`for example by the screening sheet being folded in the way
`of a four-arm star-configuration profile. Owing to its flex
`ibility, the screening sheet can be applied in virtually any
`configuration and adapted to the most varying groupings of
`lines inside the cable. A variety of examples can be seen in
`U.S. Pat. No. 6,624,359 B2, US 2003/0217863 A1 or EP 0
`915 486 A1, without however a screening sheet with a
`screening layer that is interrupted in the longitudinal direc
`tion being employed in any of them.
`Further features, details and advantages of the invention
`will become apparent from the ensuing description of exem
`plary embodiments, taken in conjunction with the drawings.
`
`The problems the invention deals with can be explained
`most obviously in conjunction with high-speed data trans
`mission cables, which does however not restrict the use of
`the invention to this purpose.
`Customary data transmission cables use several of the
`above twisted pairs, for example four, which must be
`screened as the category of transmission bandwidth and
`transmission quality rises. External screening of the twisted
`pairs as well as screening of the twisted pairs one in relation
`to the other in a cable are important in this case.
`For corresponding specifications of transmission band
`width and transmission quality to be obtained, U.S. Pat. No.
`6,624.359 B2 teaches to provide the twisted pairs with a
`screening sheet which is comprised of a laminate of a
`plastic-material Substrate layer lined with a screening layer
`of metal. This document further shows the most varying
`configurations of how to fold this laminated sheet so that it
`forms an external Screening envelope placed around several
`twisted pairs and for instance an internal separating and
`Supporting structure of Star configuration. Fundamentally,
`the screening sheet is designed as a strip of material having
`a continuous screening layer, for example of aluminum or
`copper, in the longitudinal direction of the strip.
`The above design of an electrically conductive screening
`layer that is continuous in the longitudinal direction of the
`cable gives rise to problems of grounding because, given
`varying potentials at the ends of a line, high potential
`compensation currents can flow through the screening. They
`cause malfunction and possibly even damages of equipment
`connected to Such a data transmission cable.
`
`25
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`
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`
`45
`
`SUMMARY OF THE INVENTION
`
`Proceeding from these problems, it is an object of the
`invention to embody a screening sheet for electric lines and
`in particular for multi-core data transmission cables in Such
`a way that the sheet keeps its screening properties Substan
`tially unimpeded while the above-mentioned problems of
`grounding are entirely avoided.
`This object is attained by the strip-type screening sheet
`comprising spacing gaps in the screening layer which extend
`crosswise of the longitudinal direction of the strip, longitu
`dinally recurring at intervals; they serve for electrical inter
`ruption of the screening layer in the longitudinal direction of
`the Strip. Consequently, there is no continuous electrically
`conductive connection in the longitudinal direction of the
`screening sheet, which completely precludes any flow of
`potential compensation currents. But with the gaps being
`Small as compared to the rest of the screening Surface of the
`
`50
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`US 7,335,837 B2
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`3
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective diagrammatic view, partially
`broken away, of a first embodiment of a multi-layer screen
`ing sheet;
`FIGS. 2 and 3 are analogous views of a second and third
`embodiment of a screening sheet;
`FIGS. 4 and 5 are strongly diagrammatic illustrations of
`a cross-sectional and a perspective view of an internal
`Supporting and separating structure to be used in a data
`transmission cable;
`FIG. 6 is a strongly diagrammatic perspective view of a
`first embodiment of a data transmission cable;
`FIG. 7 is an illustration, by analogy to FIG. 6, of a second
`embodiment of a data transmission cable; and
`FIGS. 8 and 9 are strongly diagrammatic, perspective
`views of data transmission cables with integrated screening
`sheets that are partially folded down on themselves.
`
`5
`
`10
`
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`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`4
`The directions of this slant are opposite from one spacing
`gap 5 to another so that the pieces of foil 4 between two
`adjacent spacing gaps 5 are trapezoidal in a plan view.
`In keeping with another embodiment according to FIG. 3,
`these spacing gaps are disposed at a small acute angle W to
`the transverse direction X of the strip, but parallel to each
`other in this screening sheet 1". Thus the pieces of foil 4
`between two adjacent spacing gaps 5 are designed in the
`form of a parallelogram in a plan view.
`As regards any further details of the embodiments accord
`ing to FIGS. 2 and 3, reference is made to the description of
`FIG. 1 where identical component parts have the same
`reference numerals.
`The screening sheets 1, 1", 1", 1" described above can be
`used in the most varying configurations in electric cables
`and in particular in high-speed data transmission cables 15.
`FIGS. 4 and 5 show an internal Supporting and separating
`structure 9 a so-called spline—with the screening sheet 1'
`being folded down on itself in the longitudinal strip direction
`Z in Such a way that four separating ribs 10 of Star configu
`ration are produced. To this end, the inside substrate layer 2
`can be fixed by suitable adhesives in the areas that flank each
`other. The joint between the two longitudinal edges 11 of the
`screening sheet 1' can be seen at the left separating rib 10.
`As mentioned above, the screening layer 3 ends openly in
`the longitudinal edge 11.
`As seen in FIG. 6, twisted-pair lines 13 are accommo
`dated in each of the quadrantal Zones 12 between the
`separating ribs 10, thus screened from each other by the
`screening layer 3 inside the separating ribs 10. The entire
`array of the internal Supporting and separating structure 9
`and the four twisted-pair lines 13 are insulated by an external
`envelope 14 which again consists of a screening sheet 1".
`This strip-type screening sheet is folded down, forming a
`hose, and, for example, welded in the vicinity of its lapping
`longitudinal edges 11. Thus the total line arrangement 15 is
`completely screened to the outside.
`FIGS. 5 and 6 roughly outline the slant of the spacing gaps
`5. Noticeably, the ends of the spacing gaps 5 are displaced
`one in relation to the other in the longitudinal direction Z of
`the strip. The helical extension of the spacing gaps 5
`precludes any electromagnetic-irradiation level from being
`continuous throughout the cross-sectional area of the cable.
`In the embodiment seen in FIG. 7, the data transmission
`cable 15', by analogy to the embodiment of FIG. 6, is again
`equipped with the externally screened envelope 14, but the
`internal Supporting and separating structure is a customary
`cruciform section 16 extruded from insulating plastic mate
`rial. Standing in for the embodiments of FIGS. 6, 8 and 9.
`FIG. 7 further shows details of an external protecting jacket
`17 of polymeric insulating material that insulates the data
`transmission cable 15" mechanically outwards. To this end,
`the protecting jacket 17 envelops the screening sheet 1".
`which is applied—as illustrated in the form of a hose of
`longitudinal extension or helically wound structure, and, as
`the case may be, is tightly united there-with by way of an
`optional adhesive layer 18. In this case, stripping the insu
`lation and baring the lines 13, upon installation of the cable
`15', are facilitated as the screening sheet 1" is being stripped
`at the same time the external protecting jacket 17 is being
`removed.
`In keeping with another variation of design, provision
`may be made for an internal protecting jacket 19 which is
`applied to the basic cable element comprised of the cruci
`form section 16 and the four pairs of twisted-pair lines 13,
`to which is applied the screening sheet 1" in longitudinal
`extension of wound structure and completed by the protect
`ing jacket 17 with the adhesive layer 18.
`In the embodiment of a data transmission cable 15" seen
`in FIG. 8, a very wide screening sheet 1" is sectionally
`folded down on itself appropriately for the four twisted-pair
`
`FIG. 1 illustrates the basic design of a multi-layer strip
`type screening sheet 1. It comprises a first Substrate layer 2
`of continuous, strip-type plastic material, preferably poly
`ester, of a thickness of 9 to 50 lum. It is lined with a screening
`layer 3 that consists of individual pieces of metal foil 4
`separated from each other by a spacing gap 5. These
`rectangular pieces of foil have a typical length L of 60 to 120
`mm in the longitudinal strip direction Z. The gap width D in
`the longitudinal strip direction Z typically amounts to
`approximately 5 to 10 mm so that the ratio that the gap width
`D bears to the length Lofthe pieces of foil 4 ranges between
`1:5 and 1:25. The width of the pieces of foil 4 is slightly less
`than that of the substrate layer 2 so that the longitudinal
`edges 6 of the substrate layer 2 project by some millimeters
`over the longitudinal edges 7 of the screening layer 3. The
`metal foil of the screening layer 3 preferably consists of
`aluminum of a layer thickness between 5 and 50 lum.
`The screening layer 3 is lined with another substrate layer
`8 so that a kind of sandwich sheeting is produced. The
`substrate layer 8 consists of the same material as the
`substrate layer 2 and is tightly united with the bottom
`substrate layer 2 in the vicinity of the longitudinal edges that
`project laterally over the screening layer 3. Thus the screen
`ing layer 3 is hermetically insulated outwards.
`Durably uniting the three layers 2, 3, 8 takes place by
`suitable adhesives customary in the field of laminated sheet
`ing. For reasons of manufacture and stability, the Substrate
`layer 2 can be comprised of several layers of uniform
`material.
`FIG. 1 does not show in detail that, in lieu of the laterally
`projecting longitudinal edges, the longitudinal edge 6 of the
`top substrate layer 8 may be flush with the longitudinal edge
`of the pieces of metal foil 4 so that, when the screening sheet
`1 is wound around corresponding lines (which is going to be
`explained in detail, taken in conjunction with FIGS. 6 to 9),
`the lapping longitudinal edges of the screening sheet 1 are
`not bulky in the area of overlap.
`In keeping with another embodiment of a screening sheet
`1" seen in FIGS. 5 to 9, the longitudinal edges 6 of the
`substrate layers 2, 8 and the longitudinal edges 7 of the
`screening layer 3 may also be flush, leaving the longitudinal
`edge 7 of the screening layer 3 accessible and perceptible
`from outside.
`The embodiment of the screening sheet 1' seen in FIG. 2
`differs from that of FIG. 1 only in the way of how the
`spacing gaps 5 extend. They are not arranged strictly at right
`angles to the longitudinal direction Z of the strip, but at a
`small acute angle W to the transverse direction X of the strip.
`
`25
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`

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`US 7,335,837 B2
`
`5
`lines 13 being enveloped by the screening sheet 1" inwardly
`and outwardly. This meandering envelope of “ornamental
`cross-sectional shape of the twisted-pair lines serves for
`screening to the outside as well as between the lines 13. An
`external mechanical protecting sleeve has been omitted in
`FIG. 8 as well as in FIG. 9 for reason of clarity.
`In FIG. 9 as mentioned, two screening sheets 1" are
`placed in the shape of an Saround two adjacent twisted-pair
`lines 13, here too ensuring external and internal screening of
`the lines 13.
`
`10
`
`6
`12. A screening sheet according to claim 1, comprising at
`least two Substrate layers (2, 8), wherein one screening layer
`(3) is placed between, and lined with, two of said substrate
`layers (2, 8).
`13. A screening sheet according to claim 12, wherein the
`two Substrate layers (2, 8) comprise longitudinal edges (6)
`which project over longitudinal edges (7) of the screening
`layer (3).
`14. A multi-layer, strip-type screening sheet for electric
`lines, comprising
`at least two substrate layers (2, 8) of a plastic material; and
`at least one screening layer (3) of an electrically conduc
`tive material which is placed between, and lined with,
`two of said substrate layers (2, 8):
`the screening layer (3) having a layer thickness between
`5 and 50 Lum and being provided with spacing gaps (5)
`that interrupt electrical conduction therein in a longi
`tudinal strip direction (Z), with the spacing gaps (5)
`extending crosswise of the longitudinal strip direction
`(Z) and recurring at longitudinal intervals (p).
`15. A screening sheet according to claim 14, wherein the
`spacing gaps (5) recur at periodical intervals.
`16. A screening sheet according to claim 14, wherein the
`spacing gaps (5) extend at an acute angle (W) in relation to
`a transverse strip direction (X).
`17. A screening sheet according to claim 14, wherein two
`Successive spacing gaps (5) extend in opposite angular
`directions in relation to the transverse strip direction (X)
`such that the foil pieces (4) that remain there-between have
`a shape of a trapezoid.
`18. A screening sheet according to claim 14, wherein two
`successive spacing gaps (5) extend in parallelangular direc
`tions in relation to the transverse strip direction (X) such that
`the foil pieces (4) that remain there-between have a shape of
`a parallelogram.
`19. A screening sheet according to claim 14, wherein the
`screening layer (3) is made of a metal foil which is separated
`into foil pieces (4) by said spacing gaps (5) and wherein a
`ratio that a spacing-gap width (D) bears to a length (L) of
`said foil pieces (4) remaining between said spacing gaps (5)
`ranges between 1:5 and 1:25.
`20. A screening sheet according to claim 14, wherein the
`two Substrate layers (2, 8) comprise longitudinal edges (6)
`which project over longitudinal edges (7) of the screening
`layer (3).
`21. An electric cable (15, 15, 15") comprising at least one
`line (13), comprising an external envelope (14) comprised of
`said screening sheet (1, 1", 1", 1") according to claim 14.
`22. An electric cable according to claim 21, wherein the
`external envelope (14) is enclosed by a protecting jacket
`(17).
`23. An electric cable according to claim 21, wherein an
`adhesive layer (18) is disposed between the envelope (14)
`and the protecting jacket (17).
`24. An electric cable according to claim 21, wherein a
`protecting jacket (19) is disposed between the at least one
`line (13) and the external envelope (14).
`25. An electric cable (15, 15, 15"), comprising at least one
`line (13), comprising an internal Supporting and separating
`structure (9) comprised of said screening sheet (1, 1", 1", 1")
`according to claim 14.
`26. An electric cable according to claim 25, wherein the
`internal Supporting and separating structure (9) is comprised
`of said screening sheet (1, 1", 1", 1") that is at least
`sectionally folded down on itself in a longitudinal direction.
`
`k
`
`k
`
`k
`
`k
`
`k
`
`15
`
`25
`
`What is claimed is:
`1. A multi-layer, strip-type screening sheet for electric
`lines, comprising
`at least one substrate layer (2, 8) of a plastic material; and
`at least one screening layer (3) of an electrically conduc
`tive material which the substrate layer (2, 8) is lined
`with:
`the screening layer (3) having a layer thickness between
`5 and 50 Lum and being provided with spacing gaps (5)
`that interrupt electrical conduction therein in a longi
`tudinal strip direction (Z), with the spacing gaps (5)
`extending crosswise of the longitudinal strip direction
`(Z) and recurring at longitudinal intervals (p),
`wherein the screening layer (3) is made of a metal foil
`which is separated into foil pieces (4) by said spacing
`gaps (5) and wherein a ratio that a spacing-gap width
`(D) bears to a length (L) of said foil pieces (4) remain
`ing between said spacing gaps (5) ranges between 1:5
`and 1:25.
`2. A screening sheet according claim 1, wherein the
`spacing gaps (5) recur at periodical intervals.
`3. A screening sheet according to claim 1, wherein the
`spacing gaps (5) extend at an acute angle (W) in relation to
`a transverse strip direction (X).
`4. A screening sheet according to claim 3, wherein two
`Successive spacing gaps (5) extend in opposite angular
`directions in relation to the transverse strip direction (X)
`such that the foil pieces (4) that remain there-between have
`a shape of a trapezoid.
`5. A screening sheet according to claim 3, wherein two
`Successive spacing gaps (5) extend in parallel angular direc
`tions in relation to the transverse strip direction (X) such that
`the foil pieces (4) that remain there-between have a shape of
`45
`a parallelogram.
`6. An electric cable (15, 15, 15"), comprising at least one
`line (13), comprising an external envelope (14) comprised of
`said screening sheet (1, 1", 1", 1") according to claim 1.
`7. An electric cable according to claim 6, wherein the
`external envelope (14) is enclosed by a protecting jacket
`(17).
`8. An electric cable according to claim 6, wherein an
`adhesive layer (18) is disposed between the envelope (14)
`and the protecting jacket (17).
`9. An electric cable according to claim 6 , wherein a
`protecting jacket (19) is disposed between the at least one
`line (13) and the external envelope (14).
`10. An electric cable (15, 15, 15"), comprising at least one
`line (13), comprising an internal Supporting and separating
`structure (9) comprised of said screening sheet (1, 1", 1", 1")
`according to claim 1.
`11. An electric cable according to claim 10, wherein the
`internal Supporting and separating structure (9) is comprised
`of said screening sheet (1, 1", 1", 1") that is at least
`sectionally folded down on itself in a longitudinal direction.
`
`30
`
`35
`
`40
`
`50
`
`55
`
`60
`
`65
`
`