Patent Publication Number: US-7896672-B2

Title: EMI suppression for electrical connector

Description:
BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to electrical connectors, and more particularly, to EMI suppression for electrical connectors. 
     Electrical connectors such as Ethernet connectors, RJ connectors and the like are commonly used as the interface between data cables and networking and telecommunications equipment. Typically, a jack connector is associated with the equipment and a plug connector is provided at an end of a cable and is mated with the jack connector. High-speed digital signals entering and/or leaving the system by means of these connectors and their associated cables are prone to having Electromagnetic Interference (EMI) problems at, the interface of the connectors. The EMI problems are more noticeable at higher transmission speeds. As Ethernet connectors are pushing higher speeds; such as 10 Gbps, the connectors radiate noise causing the EMI problems. At high speeds, the radiated noise is even a problem when the connectors are unmated. For example, the contacts within the jack connector may act as antennas and cause the EMI problems to be exacerbated. For example, the jack connectors are typically arranged as an array within the equipment in close proximity to other jack connectors. EMI caused by one jack connector interferes with the performance of adjacent jack connectors. 
     Accordingly, there remains a need for jack connectors which reduce EMI problems. There remains a need for jack connectors that reduce the potential for the contacts within the jack connector to act as antennas. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, an electrical connector is provided including a housing having a cavity configured to receive a plug therein. Contacts are arranged within the cavity for mating with a plug. The contacts include shield interfaces. A metal strip is arranged within the cavity and is electrically connected to a ground. The shield interfaces of the contacts engaging the metal strip when no plug is loaded in the cavity, and the shield interfaces disengaging from the metal strip when the plug is loaded in the cavity. 
     In another embodiment, an electrical connector is provided including a housing and contacts arranged within the housing. The contacts are deflected when mated with a plug from a relaxed state to a deflected state. A grounded metal strip is positioned within the housing. The contacts engage the metal strip when the contacts are in the relaxed state. 
     In a further embodiment, an electrical connector is provided that includes a housing having a cavity configured to receive a plug therein. A circuit board is held within the housing that is electrically connected to a ground. Contacts are arranged within a cavity for mating with a plug. The contacts are terminated to the circuit board. A metal strip is arranged within the cavity that is electrically connected to the circuit board. The metal strip is connected to the ground via the electrical connection with the circuit board. The contacts are configured to engage the metal strip when no plug is loaded in the cavity, and the contacts are configured to be held away from the metal strip by the plug when the plug is loaded in the cavity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a connector system having a plug and a jack. 
         FIG. 2  is a cross-sectional view of the plug mated with the jack. 
         FIG. 3  is a cross-sectional view of the jack without the plug therein. 
         FIG. 4  is a front view of the jack. 
         FIG. 5  is a cross-sectional view of an alternative jack. 
         FIG. 6  is a cross-sectional view of another alternative jack. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a connector system  10  having a plug  12  and a jack  14 . The connector system  10  represents a data communication system having electrical connectors defining a mating interface between a cable and a circuit board, or alternatively, between different cables. The plug  12  constitutes a first electrical connector and the jack  14  constitutes a second electrical connector. The plug  12  and the jack  14  are used to transmit data within the connector system  10 . Optionally, power may be transmitted by the cables and across the mating interface of the plug  12  and the jack  14 . For example, the connector system  10  may constitute a power-over-Ethernet (POE) system with the plug  12  and the jack  14  representing Ethernet connectors configured to transmit power therebetween. 
     The plug  12  includes a housing  20  extending between a mating end  22  and a terminating end  24 . The terminating end  24  is connected to an end of a cable  26 . The plug  12  includes a plurality of plug contacts  28  at the mating end  22 . 
     The jack  14  includes a housing  30  extending between a mating end  32  and a terminating end  34 . The terminating end  34  is connected to a circuit board  36 , such as a host board, a panel, a network switch, or another electrical component. Alternatively, the terminating end  34  may be connected to an end of a cable in a similar manner as the plug  12 . The jack  14  includes a plurality of jack contacts  38  at the mating end  22 . 
       FIG. 2  is a cross-sectional view of the plug  12  mated with the jack  14 . The housing  30  of the jack  14  includes a cavity  40  that receives the plug  12  therein. The cavity  40  is open at the mating end  32 . The jack contacts  38  are arranged within the cavity  40  for mating with the plug contacts  28 . In an exemplary embodiment, the jack contacts  38  are spring type contacts that are deflectable between a relaxed state (shown in  FIG. 3 ) and a deflected state (shown in  FIG. 2 ). The plug  12  is configured to deflect the jack contacts  38  from the relaxed state to the deflected state when the plug  12  is loaded in the cavity  40 . The jack contacts  38  are biased against the plug contacts  28  when the jack contacts  38  are in the deflected state. 
     Each jack contact  38  includes a base  42  and a tip  44  generally opposite the base  42 . The base  42  may be generally fixed in position within the housing  30 . The tip  44  is deflected when the jack contact  38  is mated with the plug  12 . The jack contact  38  has a mating interface  46 , which is the portion of the jack contact  30  that mates with the corresponding plug contact  28 . A portion of the jack contact  38  is folded over and suspended diagonally toward the tip  44  from the base  42 . The mating interface  46  is arranged along the diagonally suspended portion of the jack contact  38 . The jack contact  38  has a shield interface  48  proximate to the tip  44 . Optionally, the shield interface  48  may be defined at the tip  44 . 
     The jack  14  includes a grounded metal strip  50  arranged within the cavity  40 . The metal strip  50  is aligned with the tips  44  of the jack contacts  38 . When the jack contacts  38  are in the deflected state, the jack contacts  38  do not engage the metal strip  50 . The jack contacts  38  are held away from the metal strip  50  by the plug  12 . A gap  52  is created between the jack contacts  38  and the metal strip  50  when the jack contacts  38  are in the deflected state. The metal strip  50  is electrically connected to a ground  54  by a ground path  56 , which are represented schematically in  FIG. 2 . The ground path forms part of a grounding circuit. The grounding circuit electrically connects the metal strip  50  to the ground  54 . The ground  54  may be chassis ground, earth ground or any preferred ground. The metal strip  50  may be directly connected to the ground  54 . Alternatively, the metal strip  50  may be indirectly connected to the ground  54 , such as by a wire or a conductor extending between the ground  54  and the metal strip  50 . In the illustrated embodiment, a capacitor  58  is provided within the ground path  56  between the metal strip  50  and the ground  54 . Other electrical components may form part of the ground path  56  in addition to, or alternatively to, the capacitor  58 . In an exemplary embodiment, the jack  14  may represent a POE electrical connector configured to transmit power across the interface of the jack  14 . The capacitor  58  prevents power from being tied to the ground  54  and/or eliminates the possibility of shorting the connector. 
     The jack  14  includes a magnetics assembly  60  held within the housing  30 . The magnetics assembly  60  includes a circuit board  62  and sets of magnetics  64  connected to the circuit board  62 . The magnetics  64  may include a choke, a transformer, and/or other electrical components. The magnetics assembly  60  provides isolation and/or a reduction in noise for the signals transmitted through the jack  14 . The circuit board  62  may be mounted to the host board  36  (shown in  FIG. 1 ) or another electrical component. Such a configuration defines a board mounted jack. Alternatively, the circuit board  62  may be electrically connected to wires from a cable. Such a configuration defines a cable mounted jack. 
     Optionally, the circuit board  62  may be grounded to chassis ground, earth ground, or any preferred ground. The ground  54  may be commoned with the grounded circuit board  62 . The metal strip  50  may be electrically connected to the circuit board  62  to ground the metal strip  50 . Alternatively, the ground  54  may be separate from the circuit board  62 . The ground  54  and the circuit board  62  may be grounded to the same component. 
     The jack contacts  38  are electrically connected to the circuit board  62 . For example, the bases  42  of the jack contacts  38  may be directly terminated to the circuit board  62 . Alternatively, the jack contacts  38  may be indirectly connected to the circuit board  62 , such as by wires, conductors and the like. 
       FIG. 3  is a cross-sectional view of the jack  14  without the plug  12  (shown in  FIG. 1 ) therein. Without the plug  12  in the cavity  40  the jack contacts  38  are in the relaxed state. In the relaxed state, the shield interfaces  48  engage the metal strip  50 . When the jack contacts  38  engage the metal strip  50 , the jack contacts  38  are connected to the ground  54  through the capacitor  58 . The connection to the ground prevents the jack contacts  38  from becoming antennas and/or from being a source of noise and/or electromagnetic interference (EMI) for electrical components in the vicinity of the jack  14 . The metal strip  50  effectively ties the jack contacts  38  to the ground  54  to suppress EMI. The capacitor  58  prevents power from being tied to the ground  54  and/or eliminates the possibility of shorting the connector. 
       FIG. 4  is a front view of the jack  14  illustrating the cavity  40  and the jack contacts  38  arranged within the cavity  40 . Eight jack contacts  38  are illustrated in  FIG. 4 . Any number of jack contacts  38  may be provided in alternative embodiments. In an exemplary embodiment, the jack  14  represents an Ethernet connector. The jack  14  is an eight position eight contact socket. The jack contacts  38  are parallel to one another and equally spaced apart from one another across the mating end  32 . 
     The metal strip  50  is arranged within the cavity  40 . The metal strip  50  is positioned such that the shield interfaces  48  (shown in  FIG. 3 ) engage the metal strip  50  when the jack contacts  38  are in the relaxed state. In the illustrated embodiment, the metal strip  50  is approximately centered within the cavity  40 . Each of the jack contacts  38  engages the same metal strip  50 . As such, the jack contacts  38  are electrically commoned to one another and to the ground  54 . The capacitor  58  is provided as part of the grounding circuit between the metal strip  50  and the ground  54 . In an alternative embodiment, multiple grounded metal strips may be provided within the cavity  40 . Different jack contacts  38  may engage different metal strips. The different metal strips may be offset with respect to one another, such as in a staggered configuration, with different metal strips at different heights from the base of the housing  30  and/or at different depths from the mating end  32 . Optionally, only select ones of the metal strips may be connected to the ground  54  through the capacitor  58 . Alternatively, all of the metal strips may be connected to the ground  54  through the capacitor  58 . 
       FIG. 5  is a cross-sectional view of an alternative jack  100 . The jack  100  includes a housing  102  having a cavity  104  open at a mating end  106  of the jack  100 . The jack  100  includes a plurality of jack contacts  108  within the cavity  104  at the mating end  106 . The jack  100  includes a metal strip  110  within the cavity  104 . 
     Each jack contact  108  includes a base  112  and a tip  114 . The jack contact  108  has a shield interface  116  proximate to the tip  114 . The jack contact  108  may be curved or flat at the shield interface  116  for good contact with the metal strip  110 . The jack contact  108  is deflectable from a relaxed state to a deflected state. The jack contact  108  engages the metal strip  110  in the relaxed state. The jack contact  108  is moved to the deflected state when the plug  12  is loaded into the cavity  104 . The jack contact  108  does not engage the metal strip  110  when the jack contact  108  is in the deflected state. 
     The metal strip  110  is electrically connected to a ground  120  by ground path  122 , which are represented schematically in  FIG. 5 . A capacitor  124  is provided within the ground path  122  between the metal strip  110  and the ground  120 . Other electrical components may form part of the ground path  122  in addition to, or alternatively to, the capacitor  124 . The ground  120  may be chassis ground, earth ground or any preferred ground. In an exemplary embodiment, the jack  100  may represent a POE electrical connector configured to transmit power across the interface of the jack  100 . The capacitor  124  prevents power from being tied to the ground  120  and/or eliminates the possibility of shorting the connector. 
       FIG. 6  is a cross-sectional view of another alternative jack  200 . The jack  200  represents an RJ-45 type socket connector. The jack  200  includes a housing  202  having a cavity  204  open at a mating end  206  of the jack  200 . The jack  200  includes a plurality of jack contacts  208  within the cavity  204  at the mating end  206 . The jack  200  includes a metal strip  210  within the cavity  204 . The metal strip  210  is electrically connected to a ground  212  by a ground path  214 , which are represented schematically in  FIG. 6 . The ground path  214  is part of the grounding circuit. In the illustrated embodiment, the ground path  214  is represented by one or more traces  250  on a circuit board  222 . A capacitor  252  is coupled to the circuit board  222 . The traces  250  are electrically connected to the capacitor  252 . The traces  250  are electrically connected to the ground  212 . 
     Each jack contact  208  includes a base  216  and a tip  218 . The jack contact  208  has a shield interface  220  proximate to the tip  218 . The jack contact  208  is deflectable from a relaxed state to a deflected state. The jack contact  208  engages the metal strip  210  in the relaxed state. The jack contact  208  is moved to the deflected state when the plug  12  is loaded into the cavity  204 . The jack contact  208  does not engage the metal strip  210  when the jack contact  208  is in the deflected state. 
     The jack  200  includes a circuit board  222  arranged within the housing  202 . The bases  216  of the jack contacts  208  are connected to the circuit board  222 . The circuit board  222  includes a first side  224  and a second side  226 . The first side  224  is parallel to and faces the mating end  206 . Wire terminating contacts  228  extend from the second side  226 . Wires  230  of a cable  232  are terminated to the wire terminating contacts  228 . The ground  212  is provided on the circuit board  222 . The metal strip  210  is electrically connected to the circuit board  222  and the ground  212  on the circuit board  222 . 
     Optionally, the housing  202  may be shielded. For example, a metal shield  240  may surround the housing  202 . Alternatively, the housing  202  may be metalized, such as by a plating process, to shield the housing  202 . The metal shield  240  may be grounded, such as when the jack  200  is mounted within a chassis or a panel (shown in phantom). The ground  212  is electrically commoned with the metal shield  240 . For example, the circuit board  222  is electrically connected to the metal shield  240  surrounding the housing  202 . In an alternative embodiment, the ground  212  may be defined by the housing  202 , which may be shielded such as by being metalized. The metal strip  210  may be directly or indirectly connected to the shielded housing  202 . 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means—plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.