Note: Descriptions are shown in the official language in which they were submitted.
2 1 64398
1-
--1--
~ODrlTAR PLIJG FOR HIGH SPEED DATA TRAI~SMT~SION
This invention relates to a modular plug cable
assembly with reduced sensitivity to electromagnetic
5 noise, such as crosstalk between adjacent lines, in
particular for use with high speed data transmission for
example in local area networks (I~aN~.
It is quite common to use shielded modular plugs for
the transmission of data in local area networks. The
10 shielding of these plugs reduces the transmission of noise
and sensitivity to external noise, thereby allowing a
higher data transmission speed than conventional non-
shielded modular plugs (as used in telephone lines). The
modular plug is compact and of relatively low cost in
15 comparison to many other data connectors for transmission
of high speed data, and it is theref ore advantageous to
use modular plugs in replacement of such connectors. Due
to the ever increasing data transmission speeds, and the
close spacing of ~uxtaposed conductors positioned in the
20 modular plug, excessive crosstalk limits the data
transmission speed capability of existing modular plugs.
The cables connected to modular plugs comprise
twisted pairs of insulated conductors surrounded by a
conductive shielding layer which is _uLLuu.lded by
25 insulation of the cable. The twisting of pairs of
conductors reduces signif icantly their sensitivity to
crosstalk and enables transmission of high speed data. The
outer shielding reduces transmission and reception of
electromagnetic noise. One of the problems is that
30 assembly of twisted pairs cable to a modular plug means
straightening end portions of the conductors which are
then inserted into receiving cavities of the modular plug
housing and terminated to insulation piercing contacts.
Some modular plugs have a plastic wire holder having
35 cavities therethrough for positioning the wire ends
therein and subsequently, trimming the wire ends and
40256 CA
Zt 64~9P~
inserting the wire holder into the modular plug. The
adaptor makes it easier to arrange the wires in the
correct order and en6ures that when inserted into the
modular plug for connection to the contacts, the correct
5 order is maintained. Referring to Figures 1-7, the
assembly of this Prior Art solution to a shielded twisted
pairs cable is shown, and will be briefly described
herebelow .
In Figure 1, a ~hiPld~d twisted pairs cable 1 is
10 shown with a strain relief rubber boot 2 mounted thereon
which is for att~l L to a modular plug 15' to protect
the cable from overbending. First, a certain length of
outer insulation of the cable is removed as shown in
Figure 2, and outer conductive shielding 3 is then pulled
15 Dver the cable to reveal the inner twisted pairs 4 of
insulated conductor wires 6 as shown in Figure 3. A
certain length of the wire 6 is then straightened and
arranged in their final juxtaposed order as shown in
Figure 3. A ~h~Pld;ntJ cover 8 is then mounted over the
20 cable with a rear end positioned over the shielding 3 as
shown in Figure 5.
An adaptor 10 ' has conductor receiving cavities 12 '
within which the cable ends 6 are inserted as shown in
Figure 5. A front face 14' of the adaptor 10' can be used
25 as a reference surface for tri ln~ the wire ends such
that they are all at the same length. The modular plug can
then be inserted over the adaptor and pushed over the
wires such that the adaptor is pushed away from the wire
ends which are inserted into wire receiving cavities 16 '
3 0 of the modular plug 15 ' until the wire ends abut the end
wall 17 ' as shown in Figure 6 . Insulation piercing
contacts are then pressed such that they pierce through
the insulation to contact the conducting strands of the
wires. The wire ends must be very close or abut the end
35 wall 17' in order to ensure that all of the wire ends are
pierced by the contacts 18 as shown in Figure 7 which
40256 CA
2~ 643qp~
--3--
~hows a fully assembled shielded modular plug.
The wire ends 6 have to be straightened (untwisted)
to allow for the rearward sliding movement of the adaptor
with respect to the cable, where a certain amount of extra
5 slack is required in order to ensure that none of the
conducting wires, for example due to the twist, are drawn
backwards during insertion into the modular plug cavities
16 which could lead to non-connection with one of the
contacts 18.
One of the problems with this modular plug is that
the required length of straightened cable ends 6 limits
the data transmission rate below a certain standardised
value (category 5) desired in many LAN applications.
It would therefore be desirable to maintain the pairs
of cables twisted and have the 6hortest po6sible
straightened ends to minimize crosstalk.
It is therefore an object of this invention to
provide a modular plug cable assembly for connection to
twisted pairs cable that has reduced crosstalk.
It is a further object of this invention to provide
a cost-effective and reliable connector assembly for
connection to a twisted pairs cable for higher speed data
transmi66ion .
It i8 further object of this invention to provide a
modular plug cable a66embly for category 5 applications.
The objects of this invention have been achieved by
providing an assembly comprising a modular plug having a
6eparate wire holder having cavitie6 ~YtF~n~l i n~
therethrough for arranging and holding wires of twisted
3 0 pair6 cable in a predetermined order, the adaptor
mountable within a receiving cavity of a housing of the
modular plug for connection to contact6 of the modular
plug, wherein the wire holder has an extension extending
from the wire receiving cavities to a position proximate
3 5 ends of the wires, the length of wire between the ends of
the wire and a forward end of the cavities forming a zone
40256 C~
2 1 643~8
. ~
--4--
of contact where the plug contact6 are connected to the
wires, and wherein a rear face of the cavity housing is
tightly abuttable against the twist of the cable wire
pairs .
The preferred embodiment of thi6 invention will now
be described in detail with reference to the figures,
whereby;
Figure 8 i5 a cross-sectional view of a modular plug
according to this invention for connection to a shielded
twisted pairs cable;
Figure 9 is an isometric view of an assembly having
the cable mounted to a wire holder of the modular plug;
Figure lOa is a cross-sectional view through the
modular plug (without wire) in the wire receiving
position;
Figure lOb is the same cross-section as Figure lOa
but with the contact in the final ~mnPcted position;
Figure 11 is a cross-sectional view through lines 11-
11 of Figure 9 with the wires removed;
Figures 12a and 12b are other embo~ Ls of the wire
holder mountable to the modular plug of Figure 8;
Figure 13 is an isometric view of another embodiment
of a wire holder mountable to a modular plug;
Figure 14 is a top view of the wire holder of Figure
13 mounted in a modular plug housing partially shown in
cross-section; and
Figure 15 is another Pmhorl; r- t of a modular plug
with the wire holder of Figures 13 and 14, this Pmhor~;r-nt
6hown in cross-section.
Referring to Figure 8, a modular plug 15 for
connection to twi6ted pairs 4 of a twisted pair cable 1
comprising outer shielding 3, comprises a housing 13,
insulation piercing contacts 18, wire holder 10 and
conductive shielding 8 for connection to the shielding 3
of the cable. Outer dimensions of the modular plug 15 are
similar to the prior art modular plug 15' for
40256 CA
21 64398
--5--
interconnection to standardized modular jacks. Mounting of
the shielding 8 to the cable and to the hou6ing 13, as
well as mounting and design of the rubber boot 2 are
6imilar to that of the prior art as shown in Figure6 1-7.
Construction of the contacts 18, and their assembly and
piercing of the wire conductors 4 is similar to that
described in the prior art. The modular plug is a
relatively widely used conventional product and the prior
art aspects as mentioned above will not be described in
any great detail hereafter.
The invention principally relates to the wire holder
and its cooperation with the housing 13 and twisted pairs
cable 4, these aspects being ll i Ac~ d herebelow .
Referring to Figures 9-11, an ~ho~ll nt of the wire
holder 10 according to this invention is shown. The wire
holder 10 compriseE; a wire receiving housing 20 having
cavities 22 extending therethrough from a wire receiYing
end 24 to a contact end 25, the housing 20 comprising a
top wall 26, side walls 28, and a base wall 30. Adjacent
cavities 22 are interconnected, whereby wall portion 32,34
protruding towards each other from the top and base walls
26,30 respectively are separated by a gap. The wall
protrusions 32,34 define the wire receiving cavities 22
for positioning and holding the wires in juxtaposed
alignment for connection to insulation piercing contacts
18 .
The base wall 30 has a forward extension 35 which
extends from the contact end 25 of the housing 20 to a
trimming end 36, the base wall having a further rearward
extension 37 extending from the wire receiving end 24 of
the housing 20 rearwardly to a cable end 38. There are
also side wall extensions 40 extending from the contact
end 25 of the side walls 28 up to the trimming end 36.
There are further side wall extensions 42 extending from
the wire receiving end 24 of the side walls 28 rearwardly
towards the cable end 38. The front base wall extension 35
40256 CA
21 64398
comprises wall protrusions 44 that are extensions of the
base wall protrusions 34 for defining wire receiving
grooves 4 6 .
The wire holder 10 is insertable into a wire holder
5 receiving cavity 48 of the modular plug housing 13 whereby
the base forward extension 35 is positionable below
insulation piercing tips 50 of the contacts 18. In the
fully inserted position as shown in Figures lOa and lOb,
the top wall 26 of the housing 20 is positioned below a
10 strain relief member 52 of the housing 13. The wire holder
receiving cavity 4 8 extends f rom an open receiving end 4 9
to a closed front end 51 proximate the contacts 18. The
contacts 18 are positioned in contact receiving cavities
53 that intersect the cavity 48 for insertion of the
15 contacts 18 into the wire holder receiving cavity 48
proximate the front end 51.
Assembly of the modular plug 15 to the cable 1 will
now be described with reference to Figures 1-4, 9, lOa and
lOb. Firstly, the cable is prepared as previously
20 de6cribed with reference to Figures 1-4, except for the
~oce.luL~ of straightening the twisted pairs wires
extending from the end of the cable outer insulation. In
the embodiment of this invention, the twisted pairs
extending from the end of the cable insulation are
25 maintained with a few twists and their ends straightened
thereafter. The length of twisted wires extending from the
cable end to the straightened and rearranged wire ends 6
should be slightly greater than the rear base wall
extension 38 of the wire holder 10. The straightened wire
3 0 ends 6 are then inserted into the corresponding cavities
22 of the wire holder, where the wire ends are
sufficiently long to project beyond the front end 36 such
that they can be grasped and the wire holder pulled
towards the cable until all slack in the straightened
35 cable ends is taken up and the rear end 24 of the wire
holder housing 20 abuts the twisted pairs. Further pulling
40256 CA
~ 2 ~
--7--
of the straightened cable ends through the cavities 2 0
tightens the twist of the twisted pairs extending from the
cable outer insulation end against the holder housing rear
end 24 formed by the top wall 26, 6ide walls 28 and base
5 wall 3 0 .
The portions of the wire ends extending beyond the
front end 36 can then be trimmed, the front end 36 of the
base wall extension 35 serving as a reference for trimming
the wire ends. The wire holder 10 and wire end 6 can thus
10 be inserted into the cavity 48 of the modular plug until
full insertion where the contact insulation piercing tips
50 are positioned above the wire ends 6 that extend
between the housing contact end 25 and the base wall
extension front end 36. The contacts 18 can then be
15 depressed a6 shown in lOb into the cavity 48 such that
they pierce through the insulation of the conducting wire
6 and make contact with the inner conducting strands (as
shown in Figure 8 ) .
The strain relief member 52 is then depressed against
20 the top wall 26 of the wire holder, which is sufficiently
flexible to clamp down on the wires in the cavities 22,
thus gripping both the wire holder and wires in the
housing 13.
Due to the tightening of the wire holder against the
25 twisted pairs 4, the straightened portion of wire ends 6
are of a minimum length thereby leading to reduced
crosstalk in comparison to the prior art. Furthermore, due
to the trimming of the wire ends in their f inal position
with respect to the wire holder, and non-movement of the
30 wire holder with respect to the wire ends 6 when inserting
into the plug housing 13, there is no risk of a wire being
pushed or buckled backwards during insertion into the plug
housing cavity 48, thereby ensuring that all wires will be
reliably and correctly connected to their corresponding
35 contacts 18. A further advantage is that once the wire
holder is assembled to the wire ends 6, the wire ends 6
40256 CA
21 64398
--8--
are in their final position and their disposition can be
clearly visibly checked prior to insertion into the plug
housing cavity 48, whereby the order cannot be changed due
to the positioning of the wire ends into the cavities 22
and grooves 46 with no further r ~ being made during
insertion and connection to the wires. Active tightening
of the wire holder again6t the twists of the twisted pairs
ensures that the straightened length of the wire ends is
substantially the same and always a minimum, thus ensuring
a reliable connection with small tolerances and; uv~
data transmission speed capability.
Referring to Figures 12a and 12b, further variants of
wire holders are shown where wire holders 110 and 210 have
fewer wire receiving cavities for applications where less
conductors are required. In the prior art, applications
with less wires are often connected to the modular plug by
moulding a plug housing with different wire receiving
cavities. This however requires producing different
moulding dies for different plug hou6ing6, which i6 more
c06tly than r ltl;n~ different wire holder6. Furthermore,
the wire holders make it very easy to see the order and
position of the wire ends, whereby in the plug hou6ing
60me confusion may arise due to difficulty of seeing the
arrangement of the wire receiving cavities. Due to
h~nrll in~ of only one type of plug housing, h:~ntll in~ and
transportation costs are al60 reduced with no risk of
confu6ing the plug hou6ings. In Figure 12a, the wire
holder is for arranging wire pair6 on outer lateral
po6ition6, whereby the central cavities are not provided.
The rear end 124 of the housing 120 comprises tapered
lead-in surfaces 125 for assi6ting guidance of the wires
6 into their respective cavitie6. In Figure 12b, wire
pairs are arranged centrally, and the rear end 224 of the
housing 220 is provided with tapered lead-in surfaces 225
to a66i6t guidance of the wire into their re6pective
cavitie6 .
40256 CA
21 64398
g
Referring to Figures 13-14, another embodiment of a
modular plug according to this invention is shown. Most of
the features of this Pmho-l;r~t are similar to those
described for the ~mhofl;r ~ of Figures 8-12, and these
5 features will not be redescribed. Similar features will be
denoted with the same numbering as that used f or the
previously described ~mhofl;r-nt. The features of this
nt that differ from the previous will now be
described .
In Figure 13 a wire holder 310 comprises a latching
protrusion 54 positioned on the top wall 26, the
protrusion being substantially centrally placed between
the side walls 28 and having an inclined upper surface 56
extending rearwardly from proximate the contact end 25 of
the wire receiving housing 20. In Figure 15, the modular
plug 115 is shown comprising a cavity 58 extending through
the strain relief member 52 of the housing 13, the cavity
58 forming a shoulder 60 for engagement with the latching
protrusion 56 of the wire holder 310.
Referring to Figures 13 and 14, the wire holder 310
further comprises centering chamf ers 62 at the trimming
end 36 of the side walls 28 that cooperate with
corrPfip~ i n~ oblique surf aces 64 of the modular plug
housing 13, the surfaces 62, 64 abutting each other once
the wire holder 310 has been fully inserted into the
cavity 48 of the modular plug housing 13. Upon full
insertion, the latch 56 engages with the housing shoulder
60 for retention of the wire holder therein.
The wire holder 310 further comprises arcuate
protrusions 66 extending from the side walls 28 and
positioned proximate a wire receiving end 24 of the wire
receiving housing 20, these protrusions 66 extending
further outwardly than the width of the wire holder
receiving cavity 48 of the housing 13 such that there is
an interference fit between the side wall protrusions 66
and side walls 68 of the cavity 48. The side walls 28 have
40256 CA
~ 43~
--10--
a certain resiliency thus allowing elastic inward biasing
of the protru6ion 66 when the wire holder 310 is inserted
into the modular plug housing cavity 48. Due to the
positioning of the protrusion 66 proximate a wire
receiving end of the wire holder 310, the trimming end 36
is able to pivot slightly, whereby the cooperation of the
side wall tapered centering surface6 62 and the oblique
housing side wall 6urfaces 64 provide a means of centering
the wire receiving grooves 3 6 accurately with respect to
the modular plug housing, and therefore with respect to
the contacts 18. Furth~ c:, cooperation of the latch
protrusion 56 of the wire holder with the corresponding
housing latching means 58 ensures that the wire holder is
fully inserted into the modular plug housing 13 and
securely held in that position prior to, and during
connection of the contacts 18 to the wires. The inherent
elasticity of the wire holder top wall 26 allows resilient
biasing of the latch protrusion 56 for insertion into the
wire holder receiving cavity 48.
Accurate positioning, and full insertion of the wire
ends for connection to the contacts 18 is thus ensured,
thereby enabling provision of the shortest possible
straightened lengths of wire ends 6, and a reliable
connection thereto.
Advantageously therefore, the invention provides a
more reliable connection to twisted pairs cable, with
higher data transmission speed capability.
40256 CA
