EP1074068B1

EP1074068B1 - Modular electrical plug and plug-cable assembly including the same

Info

Publication number: EP1074068B1
Application number: EP99914025A
Authority: EP
Inventors: Richard Marowsky; Robert Colantuono; Ronald Locati
Original assignee: Stewart Connector Systems Inc
Current assignee: Stewart Connector Systems Inc
Priority date: 1998-03-20
Filing date: 1999-03-19
Publication date: 2004-09-15
Anticipated expiration: 2019-03-19
Also published as: AU760804B2; CN1305652A; AU3196799A; EP1074068A1; JP2002510854A; DE69920202D1; NO20004669D0; WO1999052182A1; DE69920202T2; EP1074068A4; CN1134862C; HK1041112A1; NO20004669L; IL138569A0

Description

FIELD OF THE INVENTION

The present invention relates to assemblies of the modular plug and a multi-wire cable terminated at one end by the plug and at the other end by another plug or another electrical connector.

BACKGROUND OF THE INVENTION

Data communication networks are being developed which enable the flow of information to ever greater numbers of users at ever higher transmission rates. However, data transmitted at high rates in multi-pair data communication cables have an increased susceptibility to crosstalk, which often adversely affects the processing of the transmitted data. Crosstalk occurs when signal energy inadvertently "crosses" from one signal pair to another. The point at which the signal crosses or couples from one set of wires to another may be 1) within the connector or internal circuitry of the transmitting station, referred to as "near-end" crosstalk, 2) within the connector or internal circuitry of the receiving station, referred to as "far-end crosstalk", or 3) within the interconnecting cable.

Near-end crosstalk ("NEXT") is especially troublesome in the case of telecommunication connectors of the type specified in sub-part F of FCC part 68.500, commonly referred to as modular connectors. The EIA/TIA (Electronic/Telecommunication Industry Association) of ANSI bas promulgated electrical specifications for near-end crosstalk isolation in network connectors to ensure that the connectors themselves do not compromise the overall performance of the unshielded twisted pair (UTP) interconnect hardware typically used in LAN systems. The EIA/TIA Category 5 electrical specifications specify the minimum near-end crosstalk isolation for connectors used in 100 ohm unshielded twisted pair Ethernet type interconnects at speeds of up to 100 MHz.

A typical modular jack includes a housing having a cavity therein of a size for receiving a modular plug, where the cavity is provided with a plurality of cantilevered spring contacts which correspond to a like plurality of contact terminals in the mating modular plug. The modular plug receives discrete, insulated, stranded or solid conductors in conductor-receiving channels or slots formed in a dielectric housing. Flat, blade-like metallic terminals are then inserted into individual vertically oriented slots in the housing in a generally side-by-side arrangement with contact portions thereof extending into engagement with the conductors. When the plug is inserted into a modular jack, the cantilevered portions of the terminals in the jack engage portions of associated terminals in the plug.

Referring to prior art, U.S. Patent No. 4,516,822 describes the subject-matter of the preambles of claims 1, 7 and 11. The U.S. Patent describes an assembly of a modular plug for terminating multi-wire cable including a cable jacket covering wires. The plug includes a housing defining a plurality of terminal-receiving slots and a longitudinal cavity extending from a rear surface of the housing to a location below the slots and in communication with the slots. An anchoring member or strain relief element is arranged on the housing. Contact terminals are arranged in the slots. A base or load bar defines a plurality of wire-receiving channels between parallel planar partitions for receiving the wires of the cable. A forward part of the load bar is arranged in the cavity opposite the strain relief element to fix the wires of the cable in position.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide new and improved modular plugs and modular plug-cable assemblies including the same.

It is another object of the invention to provide new and improved plugs having the ability to terminate different cables which have cable jackets and wires of different sizes and plug-cable assemblies formed from such plugs and cables.

A modular plug in accordance with an embodiment of the present invention includes a housing made of dielectric material including a plurality of parallel, spaced, longitudinally extending terminal-receiving slots at a forward end and a longitudinal cavity extending from a rear face thereof forward to a location below the slots such that the cavity is in communication with the slots. Each terminal-receiving slot receives a respective contact terminal or contact blade, e.g., an insulation displacing contact. The plug also includes a management or load bar (hereinafter referred to only as a load bar) which is inserted into the cavity and is preferably longitudinally coextensive with the cavity. The load bar defines wire-receiving channels in two substantially parallel rows. The wire-receiving channels are staggered in relationship to one another. To terminate a multi-wire cable by the plug, the cable jacket of the cable is slit to expose a length of the wires. The wires are inserted into the wire-receiving channels of the load bar, which are formed to enable secure retention of the wires. A portion of the upper section of the slit cable jacket is cut so that a remaining portion has a sufficient length to overlie a rearward portion of the load bar which includes the location at which the strain relief element of the plug will be crimped. Similarly, a portion of the lower section of the slit cable jacket is cut so that a remaining portion has a length sufficient to underlie the rearward portion of the load bar. The load bar, with the overlying and underlying portions of the cable jacket, is then inserted into the cavity in the plug housing. Contact terminals in the terminal-receiving slots are pressed into the wires to pierce the insulation of the wires and engage the metal wire therein. The strain relief element on the plug is then crimped to engage the cable jacket overlying the rearward portion of the load bar and securely fix the cable in the plug.

In this manner, the wires are in pre-determined positions below the strain relief element to thereby avoid any randomness in the arrangement of the wires in the plug. As a result, variations in NEXT and TOC values between wire pairs in plugs having substantially the same design are significantly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily understood by reference to the following detailed description when considered in connection with the accompanying drawings in which:

FIG. 1 is an exploded perspective view of a plug in accordance with an embodiment of the invention, which provides reduced variations in NEXT and TOC values;

FIG. 2 is an exploded perspective view of the plug of FIG. 1 showing the conductors inserted into the load bar of the plug;

FIG. 3 is another exploded perspective view of the plug of FIG. 1;

FIG. 4 is a rear view of the housing of the plug of FIG. 1;

FIG. 5 is a perspective view of the load bar of the plug of FIG. 1;

FIG. 6 is another exploded perspective view of the plug of FIG. 1;

FIG. 7 is a schematic view of the plug of FIG. 1 terminating a multiconductor cable;

FIG. 8 is a schematic view of the terminated cable prior to insertion into the plug of FIG. 1;

FIG. 9 is a longitudinal cross-sectional view of the assembled plug shown in FIG. 1;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings wherein like reference characters designate identical or corresponding parts throughout the several views,

An embodiment of a plug in accordance with the invention is shown in FIGS. 1-9. Said embodiment and provides consistent TOC performance and NEXT performance. In this embodiment, plug 140 includes a housing 142 made of dielectrical material and a load bar 144. Housing 142 bas the dimensions of a standard RJ45 plug and includes a latch 146 projecting from a lower surface 148. Housing 142 also includes parallel, spaced, longitudinal extending terminal-receiving slots 150 formed in an upper surface 152 at a front end of the housing 142 and a longitudinal cavity 154 extending from a rear face 156 of the housing 142 inward to a location below the terminal-receiving slots 150. A rearward portion 158 of the cavity 154 bas a substantially rectangular cross-section while a forward portion 160 of the cavity 154 is constructed so that it is adapted to receive the forward end 162 of the load bar 144 having the conductors or wires of a cable terminated by the plug inserted thereon. The load bar 144 is preferably substantially longitudinally coextensive with the cavity 154. The rearward portion 158 of the cavity 154 tapers inward from the rear face 156. A strain relief element 164 extends from an upper surface 152 of housing 142 and has a lower surface extending close to or in the rearward portion 158 of the cavity 154.

Load bar 144 is made of a dielectric material and includes wire-receiving channels 166, four channels in each of two rows in the illustrated embodiment. The channels 166 are staggered in relation to one another and are dimensioned to receive different-sized wires. The channels 166 are open in order to facilitate easy insertion of the wires 168 and constructed to facilitate secure retention of the wires 168 in the channels 166. More specifically, each channel 166 is formed by a longitudinally extending, arcuate surface 170 which forms a cradle receivable of a wire 168 (FIG. 5). Projections 171 are thereby formed between adjacent channels 166. The projections 171 formed between the channels 166 in the lower row are truncated before the forward edge of the load bar 144 to thereby form a sort of step in a forward end 172 of the load bar 144 in which the channels 166 in the lower row are defined by an underlying surface and the channels 166 in the upper row are defined by opposed side surfaces.

The forward end 172 of the load bar 144 is dimensioned to allow for complete insertion into the forward portion 160 of the cavity 154 and the rear end 173 of the load bar 144 is dimensioned to allow for complete insertion into the rearward portion 158 of the cavity 154. The forward portion 160 of the cavity 154 thus provides opposed upper and

lower surfaces

174, 176 along which the wires 168 in the lower row slide during insertion of the load bar 144 into the plug housing 142 until they abut against the from end of the cavity 154, and opposed side surfaces 178 and an upper surface 180 along which the wires 168 in the upper row slide during insertion of the load bar 144 into the plug housing 142 until they abut against the front end of the cavity 154 (FIG. 9). The upper surfaces 176,180 include a slit therein through which the contact terminals 182 pass in order to pierce the wires 168 (see FIG. 9).

An important feature of the load bar 144 is that it includes a "hinge" to enable rotational movement of a rearward portion of the load bar 144 relative to a forward portion. This movement may be realized once the load bar 144 is inserted into the cavity 154 and the forward portion thereof fixed within the cavity 154. More specifically, the load bar 144 includes aligned transverse slits 184 in the projections 171 and in the edge portions 145 on both sides. The presence of slits 184 allows the rear portion 186 of the rear end 173 of the load bar 144 to flex with respect to the front portion 188 of the rear end 173 and the front end 172 of the load bar 144. The flex is necessary for reasons discussed below.

By means of the load bar 144, the entire portion of each of the wires 168 within the plug housing 142 is positioned in a precise, pre-determined position, including at the location below the strain relief element 164. In this manner, a random arrangement of any portion of the wires 168 within the plug 140 is avoided. The position of the portion of each of the wires 168, which is to be engaged by the terminals 182 is also in a pre-determined position. At a minimum, in a plug in accordance with the invention, it is desirable that the portion of the wires between the location below the strain relief element 164 and the terminals 182 is fixed in position.

To enable fastening of a cable 190 in connection with the plug 140 vis-à-vis the strain relief, as shown in FIGS. 7-9, a portion of the cable jacket or sheath 192 of the cable 190 overlies the rear portion 186 of the rear end 173 of the load bar 144. This is enabled by slitting the cable jacket 192 a distance at least as large as the length of the wires 168 required to terminate the cable 190 by the plug 140 and then cutting the slit portion of the cable jacket 192 leaving a sufficient amount of the cable jacket 192 to extend above and below the rear portion 186 of the rear end 173 of the load bar 144 about up to the slits 184. The slits 184 are formed on the load bar 144 at a location so that the strain relief element 164 is situated between the rear end of the load bar 144 and the slits 184.

To terminate the cable 190 by means of the plug 140, two opposed longitudinal slits are made in the cable jacket 192 to expose a length of the wires 168 at least as large as the length of the load bar 144. The wires 168, which are usually in twisted pairs in the cable, are untwisted and pressed into the channels 166 in the load bar 144 in correspondence with the designation of the wires 168, as in the conventional manner. The ends of the wires 168 extending beyond the load bar 144 are then cut flush with the front end of the load bar 144. The slit portions of the cable jacket 192 are cut to extend only up to the slits 184 as shown in FIG. 8. The load bar 144 having the slit portions of the cable jacket 192 alongside it is then inserted into the cavity 154 in the housing 142 until the front end of the load bar 144 abuts against the front end of the cavity 154 (FIG. 9). Since the cavity 154 is dimensioned to receive the load bar 144 without clearance below the load bar 144, and with some clearance above the load bar 144, upon insertion of the load bar 144 into the cavity 154, the slit portion of the cable jacket 192 below the load bar 144 causes an upward flex of the rear portion 186 of the rear end 173 of the load bar 144, which flexure is enabled by the slits 184 (FIG. 9). The terminals 182 in the terminal-receiving slots 150 in the housing 142 (see FIGS. 7 and 9) are then pressed into the wires 168 to pierce the insulation of the wires 168 and engage the metal cores therein. The terminals 182 may be pre-positioned in the Slots 168 so that it is only necessary to press them into the wires 168.

Thereafter, the strain relief element t64 is pressed inward or set to engage the slit portion of the cable jacket 192 overlying the rear portion of the load bar 144 to thereby secure the cable 190 in connection with the plug 140 (see FIG. 7). The pressing of the strain relief element 164 inward causes the rear portion 186 of the rear end 173 of the load bar 144 to be pressed downward against the lower surface of the cavity 154 thereby reducing the angle between the rear portion 186 of the rear end 173 and the front portion 188 of the rear end 173 and front end 172 (compare FIG. 9 to FIG. 7). The rear portion 186 is not planar with the front portion 188 in view of the presence of the cable jacket between the rear portion 186 ad the lower surface of the cavity 154.

The positioning of the wires 168 in pre-determined positions below the strain relief element 164 reduces variations in NEXT and TOC values between plugs having the same construction. In conventional plugs in which the wires are randomly arranged at the location below the strain relief element, when the strain relief element is pressed inward into the cable, the wires in the cable remain in this random arrangement and even more so, the wires are susceptible to additional random movement. This random arrangement of wires results in inconsistent NEXT and TOC values for plugs having the same design.

A particular advantage of the construction of the plug housing 142 and load bar 144 in accordance with the invention is that cables having different thicknesses of jackets and different diameter wires can be terminated by the plug 140. For the wires, the channels 166 are provided with a size equal to or larger than a relatively large diameter wire so that smaller diameter wires could also be positioned therein. For the different thicknesses of jackets, the height of the rearward portion 158 of the cavity 154 is provided with a size greater than the height of the load bar 144 and twice the thickness of the jacket of a relatively large cable. As such, cables with smaller cable jackets and insulation sheaths can.be used to surround the load bar whereby the strain relief element 164 would engage with the upper portion of the cable jacket and thereby fix the cable in connection with the plug 140.

The plug described above in FIGS. 1-9 may be used to terminate an end of a multi-wire cable whereby the other end of the cable is terminated by a similar plug or another modular connector. A plug-cable assembly is thus formed.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. Accordingly, it is understood that other embodiments of the invention are possible in the light of the above teachings.

Claims

An assembly of a modular plug (140) and a multi-wire cable (190), the plug terminating the multi-wire cable (190), the cable including a cable jacket (192) covering wires (168), the plug (140) comprising a housing (142) defining a plurality of terminal-receiving slots (150) and a longitudinal cavity (154) extending from a rear surface (156) of said housing (142) to a location below said slots (150) and being in communication with said slots (150), said housing (142) including a strain relief element (164), contact terminals (182) arranged in said slots (150), and a load bar (144) defining a plurality of wire-receiving channels (166) for receiving wires (168) of the cable (190), said load bar (144) being arranged in said cavity (154) opposite said strain relief element (164) such that the wires (168) of the cable (190) are fixed in position at least at a location opposite said strain relief element (164), characterized in that
said strain relief element (164) engages with the cable (190) and secures the cable (190) to said housing (142), and that
two opposed longitudinal slits are provided in the cable jacket (192), such that at the position of said strain relief element (164) and said channels (166) of said load bar (144), a portion of the cable jacket (192) overlies a portion of said load bar (144).
The assembly of claim 1, characterized in that said load bar (144) includes transverse slits (184) arranged between a forward portion of said load bar (144) and a rearward portion of said load bar (144) such that said rearward portion of said load bar (144) is flexible with respect to said forward portion of the load bar (144).
The assembly of claim 1, characterized in that said load bar (144) is constructed such that two parallel rows of at least two of said channels (166) are formed, said channels (166) being staggered in relationship to one another.
The assembly of claim 1, characterized in that said load bar (144) is constructed such that said channels (166) extend to a location opposite said slots (150).
The assembly of claim 1, characterized in that said load bar (144) is hinged such that a rearward portion of said load bar (144) is rotatable with respect to a forward portion of said load bar (144).
The assembly of claim 5, characterized in that said rearward portion of said load bar (144) is arranged opposite said strain relief element (164) such that pressing of said strain relief element (164) causes rotation of said rearward portion of said load bar (144) with respect to said forward portion of said load bar (144).
A modular plug (140) for terminating various multi-wire cables having different sizes, comprising a housing (142) defining a plurality of terminal-receiving slots (150) and a longitudinal cavity (154) extending from a rear surface of said housing (142) to a location below said slots (150) and being in communication with said slots (150), said housing (142) including a strain relief element (164), contact terminals (182) arranged in said slots (150), and a load bar (144) defining a plurality of wire-receiving channels (166) for receiving wires (168) of the cable (190), characterized in that
said strain relief element (164) engages with the cable (190) and secures the cable (190) to said housing (142),
the size of said load bar (144) relative to said cavity (154) is such that a rearward portion of said load bar (144) is movable within said cavity (154), and
said load bar (144) is hinged such that a rearward portion of said load bar (144) is rotatable with respect to a forward portion of said load bar (144).
The plug of claim 7, characterized in that said load bar (144) is arranged in said cavity (154) opposite said strain relief element (164) such that the wires (168) of the cable (190) are fixed in position at least at a location opposite said strain relief element (164).
The plug of claim 7, characterized in that said load bar (144) includes transverse slits arranged between the forward portion of said load bar (144) and the rearward portion of said load bar ( 144).
The plug of claim 7, characterized in that said load bar (144) is constructed such that two parallel rows of at least two of said channels (166) are formed, said channels (166) being staggered in relationship to one another.
A modular plug-cable assembly, including a multi-wire cable (190) including a cable jacket (192) and at least one plug (140) terminating a respective end of said cable (190), each of said at least one plug (140) comprising a housing (142) defining a plurality of terminal-receiving slots (150) and a longitudinal cavity (154) extending from a rear surface of said housing (142) to a location below said slots (150) and being in communication with said slots (150), said housing (142) including a strain relief element (164), a load bar (144) arranged in said cavity (154) and defining a plurality of wire-receiving channels (166), an end of each of said wires (168) of said cable (190) being arranged in a respective one of said channels (166), a portion of said load bar (144) being arranged opposite said strain relief element (164), and contact terminals (182) situated in said slots (150) and in engagement with said wires (168) of said cable (190) arranged in said channels (166), characterized in that
said cable jacket (192) of said cable (190) is arranged to cover said portion of said load bar (144) arranged opposite said strain relief element (164), and
said strain relief element (164) engages with said cable (190) at a location at which said cable jacket (192) of said cable (190) covers said load bar (144) such that said strain relief element (164) secures said cable (190) to said housing (142) and said wires (168) of said cable (190) are fixed in position at said location.
The assembly of claim 11, characterized in that said at least one plug (140) comprises first and second plugs for terminating respective first and second ends of said cable (190).
The assembly of claim 11, characterized in that said load bar (144) includes transverse slits arranged between a forward portion of said load bar (144) and a rearward portion of said load bar (144) such that said rearward portion of said load bar (144) is flexible with respect to said forward portion of the load bar (144).
The assembly of claim 11, characterized in that said load bar (144) is constructed such that two parallel rows of at least two of said channels (166) are formed, said channels (166) being staggered in relationship to one another.
The assembly of claim 11, characterized in that said load bar (144) is constructed such that said channels (166) extend to a location opposite said slots (150).
The assembly of claim 11, characterized in that said cable (190) includes a cable jacket (192), a portion of said cable jacket (192) overlying a rear portion (186) of said load bar (144) and another portion of said cable jacket (192) underlying said rear portion (186) of said load bar (144), said rear portion (186) of said load bar (144) being positioned opposite said strain relief element (164) such that said strain relief element (164) engages said portion of said cable jacket (192) overlying said rear portion (186) of said load bar (144).
The assembly of claim 11, characterized in that said load bar (144) is hinged such that a rearward portion of said load bar (144) is rotatable with respect to a forward portion of said load bar (144).
The assembly of claim 17, characterized in that said rearward portion of said load bar (144) is arranged opposite said strain relief element (164) such that pressing of said strain relief element (164) causes rotation of said rearward portion of said load bar (144) with respect to said forward portion of said load bar (144).
A method for terminating a multi-wire cable (190) with a plug (140), comprising the steps of:

slitting a cable jacket (192) of the cable (190) to expose a length of the wires (168) at least as long as the length of a load bar (144) adapted to enter into a cavity (154) of a housing (142) of the plug,

inserting the wires (168) into channels (166) in the load bar (144),

removing a portion of the slit cable jacket (192) from the cable ( 190) such that a remaining portion of the cable jacket (192) overlies and underlies a rearward portion of the load bar (144),

inserting the load bar (144) into the cavity (154) in the housing (142) of the plug (140) such that the wires (168) are brought into alignment with terminal-receiving slots (150) in the housing (142) of the plug (140) and the overlying portion of the cable jacket (192) extends beyond a strain relief element (164) of the housing (142) of the plug (140),

pressing terminals (182) disposed in the slots (150) into engagement with the wires (168), and thereafter

crimping the strain relief element (164) to engage the overlying portion of the cable jacket (192) to thereby secure the cable (190) to the housing (142) of the plug (140).
The method of claim 19, wherein the wires (168) are inserted into the channels (166) in the load bar (144) such that a portion of each wire (168) extends beyond a front edge of the load bar (144), further comprising the step of:

removing the portion of the wires (168) extending beyond the front edge of the load bar (144).
The method of claim 19, wherein the portion of the slit cable jacket (192) underlying the load bar (144) extends beyond the strain relief element (164).