Patent Publication Number: US-6981899-B1

Title: Electrical connector assembly with non-orthogonal jack stop surface for engaging plug latch abutment

Description:
FIELD OF THE INVENTION 
   The present invention relates to an electrical connector assembly formed of a jack and a plug, particularly for telecommunications and data transmission systems. The jack has a cavity for receiving the plug and holds the plug between a stop member and a latch stop, with the plug free end surface engaging the stop member and an abutment surface on a resilient latch arm of the plug engaging the latch stop. The latch stop has a non-orthogonal stop surface. 
   BACKGROUND OF THE INVENTION 
   Electrical connectors formed of a jack and a plug for telecommunications and data transmission systems are disclosed in U.S. Pat. No. 4,648,678 to Archer, U.S. Pat. No. 5,061,219 to Bolick and U.S. Pat. No. 5,399,107 to Gentry. Such connectors have limited performance capabilities, particularly for high performance data transmission at high frequencies. Performance characteristics, particularly near end crosstalk, degrade at these higher frequencies. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide an electrical connector, particularly for telecommunications and data transmission systems with enhanced performance characteristics. 
   The foregoing object is basically obtained by an electrical connector assembly comprising a jack and a plug. The jack has a housing with a plug receiving cavity and a plurality of electrical jack contacts extending into the cavity. The cavity has a plug insertion axis. A stop member is provided in the housing and has an inner end surface facing and defining an inner end of the cavity. A latch stop is on the housing at an entrance to the cavity, and has a latch surface facing the cavity and extending in a plane acutely angled relative to the plug insertion axis. The stop surface has an outer edge and an inner edge, with the outer edge being closer to the inner end surface and farther from the plug insertion axis than the inner edge. The inner end surface and the outer edge are spaced by a jack nominal dimension along a line parallel to the plug insertion axis within a jack tolerance. The plug has a plug body with a plurality of plug contacts and has a free end surface engagable with the jack contacts and with the inner end surface, respectively, when the plug body is received in the cavity. A resilient latch arm extends from the plug body and has an arm abutment with an abutment surface engagable with the stop surface when the plug is fully inserted in the cavity. The abutment surface and the free end surface are spaced by a plug nominal dimension within a plug tolerance. The difference between the jack distance and the plug distance is not greater than a sum of the jack tolerance and the plug tolerance. 
   By forming the electrical connector assembly in this manner, the play or float of the plug within the jack is limited. By limiting this float or play, the jack contacts and the plug contacts will engage more closely at the same points, as intended and designed. The failure of conventional electrical connector assemblies to repeatedly and accurately have their contacts engage at the same points causes the electrical properties to change, resulting in a degrading of the electrical performance characteristics from the ultimate design characteristics. 
   The limitation of the tolerance is relative to the difference as compensated by the non-orthogonal or autely angled orientation of the stop surface in combination with the relationships of the jack and plug nominal dimensions and jack and plug tolerances. 
   In conventional systems, too much play is provided by the tolerances and the relationship of the nominal plug dimension and the nominal jack dimension. These dimensions are concerned with providing, in all cases, an adequate minimum space such that the spacing between the plug free end surface and the plug abutment surface is always less than the distance between the housing inner end surface and the housing stop surface, even at the maximum size of the plug distance and the minimum size of the jack distance. As the conventional electrical connector assembly approaches the opposite extremes of the tolerances, further play is provided between the plug and the jack which degrades the electrical performance characteristics. By failing to maintain the designed point contact of the respective contacts, the electrical performance of the electrical connector assembly in adversely affected. 
   As used in this application, the phrase, within a tolerance means, plus or minus a tolerance dimension relative to the nominal dimension of the design. In other words, “within” is intended to mean “plus or minus”. 
   Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of this disclosure: 
       FIG. 1  is a side elevational view in section of an electrical connector assembly with the jack and plug separated; 
       FIG. 2  is a side elevational view in section of the electrical connector assembly of  FIG. 1  with the jack and plug connected. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An electrical connector assembly  10  according to the present invention includes a jack  12  and a plug  14 . Both the jack and the plug are of conventional design, except for the configuration of the housing latch stop  16  and certain dimensions of the plug and housing. These dimensions and configuration of the latch stop according to the present invention provide a more precise connection, thereby enhancing electrical performance of the electrical connector assembly. 
   Jack  12  includes a housing  18  of plastic insulating material having a plug receiving cavity  20 . A plurality of electrical jack contacts  22 , usually eight in number, are mounted in the housing and extend in a cantilever manner into cavity  20 . Plug receiving cavity  20  has or defines a plug insertion axis  24 . The inner end of cavity  20  is defined by a substantial planar inner end surface  26  that is substantially perpendicular to plug insertion axis  24 . Such surface can be continuous or interrupted, and is of a substantially conventional configuration. 
   Latch stop  16  is provided on the housing adjacent entrance  28  to cavity  20 . The latch stop has a substantially planar stop surface  30  facing into cavity  20  and extending in a plane acutely angled or non perpendicular to plug insertion axis  24 . Although surface  30  is substantially planar, it is usually interrupted with portions on each lateral side of the cavity. The stop surface has an outer edge  32  and an inner edge  34 , when viewed in a radial direction relative to insertion axis  24 . Outer edge  32  is closer to inner end surface  26  and farther from plug insertion axis  24  than inner edge  34 . 
   Inner end surface  26  and outer edge  32  are spaced by a jack nominal dimension J along a line parallel to the plug insertion axis. The jack nominal dimension is within or plus/minus a jack tolerance. The jack dimension is preferably substantially 0.232 inch, and is more preferably essentially 0.232 inch. The jack tolerance is preferably substantially plus/minus 0.002 inch, and is more preferably essentially plus or minus 0.002 inch. 
   Plug  14  has a plug body  36  supporting a plurality of electrically conductive plug contacts  38  adjacent a free end  40  of plug  14 . The plug free end defines a free end surface  42 . When the plug is insert into cavity  20 , the respective plug contacts  38  engage and form an electrical connection with the respective jack contacts  22 . Additionally, when the plug is fully inserted, free end surface  42  engages housing inner end surface  26  to limited the amount of plug insertion into cavity  20 . 
   A resilient latch on extends rearwardly and radially outwardly from free end  40  of plug body  36 . The latch on has an arm abutment  46  with a substantially planar abutment surface  48  that is substantially perendicular to plug insertion axis  24  and the longitudinal axis of plug body  36 . Abutment surface  48  is engageable with stop surface  30  when plug  14  is fully received within housing cavity  20 . 
   The abutment surface and free end surface are spaced by a plug nominal dimension P. The plug nominal dimension is within or plus/mius a plug tolerance. The plug nominal dimension is preferably substantially 0.230 inch, and is more preferably essentially 0.230 inch. The plug tolerance is preferably substantially plus or minus 0.003 inch, and more preferably essentially plus or minus 0.003 inch. 
   The difference between the jack distance and plug distance is not greater than the sum of the absolute value of the jack tolerance and the absolute value of the plug tolerance. Preferably, the distance is less than the sum, and more preferably is substantially less than the sum. 
   With the jack nominal dimension being 0.232 inch and the plug nomonal dimension being 0.230 inch, the difference between those two nominal dimensions is 0.002 inch. With the jack tolerance being plus or minus 0.002 inch and the plug tolerance being plus or minus 0.003 inch, the sum of the absolute values of the jack tolerance and plug tolerance is 0.005 inch, which sum is greater than the nominal dimensional difference of 0.002 inch. The jack dimension, with the plug tolerance, can thus be between 0.230 inch to 0.234 inch. The plug dimension with the tolerance can than be between 0.0227 inch and 0.233 inch. In this manner, the plug plug nominal dimension with the plug tolerance can be greater than the jack dimension with its tolerance. In such circumstances, abutment surface can ride up or be positioned in a suitable location on stop surface  30  between outer edge  32  and inner edge  34 , and still provide a suitable latching force by the engagement of abutment surface  38  on stop surface  30  when the plug is fully inserted within cavity  20 . 
   The angle of the planar stop surface  30  relative to plug insertion axis  24  is preferably between about 27 and 29 degrees. Such angle provides adequate flexibility, while maintaining a positive latching of the plug in the receptacle. 
   By setting the plug and jack nominal dimensions and the plug and jack tolerances in this manner, the plug is more precisely fit within cavity  20 . By more precisely fitting the plug within the cavity, the plug contacts  38  engage the jack contents  22  more precisely relative to the designed contact position. With this more precise engagement of the contacts, the electrical characteristics of the connector assembly are enhanced in that the engagement of the contacts is more closely in alignment with the design criteria to maximize electrical performance, for example, by minimizing crosstalk. When the plug can freely slide axially within the cavity, due to the distance between the housing inner end surface and stop surface being substantially greater than the distance between the plug abutment surface and free end surface, to change the engagement position of the plug contacts and the jack contacts, electrical performance of the electrical connector assembly will degrade as the engagement of the contacts moves from their optimum design positions. 
   In use, plug contacts  38  are connected conductors  50  of twisted wire pairs which are mounted within a wire support  52  and extend from the plug end opposite free end  40 . The arrangements of the twisted wire paths and the wire support are conventional, and thus, not described herein in detailed. In a similar manner the contacts  22  are similarly connected to respective wiring. 
   While one embodiment has been chosen to illustrate the invention, it would be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.