Abstract:
The present invention includes a low insertion force connector assembly capable of providing an electrical interface to a circuit board. The connector assembly includes a housing and electrically conductive terminals mounted in the housing. The connector assembly further includes slide and wedge members which are inserted into the housing along with a connective end portion of a flexible flat cable pressing exposed conductors on the flexible flat cable against terminal contact arms.

Description:
RELATED APPLICATIONS 
   This application claims benefit of priority from U.S. Provisional Patent Application No. 60/468,367, which was filed May 6, 2003, and which is hereby incorporated by reference. 

   TECHNICAL FIELD 
   The present invention relates to electrical connectors for flat cables, and more particularly relates to a connection system incorporating a low insertion force connector and a flexible flat cable. 
   BACKGROUND OF THE INVENTION 
   Flexible flat cables, which may include and which may otherwise be known as flexible circuits or flexible printed circuits, typically comprise flat flexible conductors, usually copper, that are arranged side by side on a thin, flexible sheet or film of plastic insulation such as polyethylene. The flexible conductors may also be embedded in the plastic insulator or sandwiched between two flexible sheets of plastic insulation that are bonded together. 
   Low insertion force (LIF) and zero insertion force (ZIF) connectors are known in the field for use in connecting printed circuit boards to flexible flat cables. One aspect of the known LIF and ZIF connectors is that a flexible flat cable having exposed conductors is inserted into a LIF or ZIF connector that is soldered or otherwise affixed to a printed circuit board. However, this presents hazards during assembly in applications where a powered flexible circuit must be attached to a circuit board. In one such application, a lithium battery is used to provide power. The battery is attached to an electronic control circuit board to monitor and control voltage. The use of known LIF and ZIF connectors exposes assembly operators to uncovered powered circuit traces when assembling the connection. 
   Known LIF and ZIF connectors typically lack positive locks to verify full insertion of the flexible cable to the circuit and secondary locks to improve assembly reliability. In many known LIF and ZIF connectors it is difficult to accurately align the flexible cable to the connector or circuit board resulting in shorting across circuits. In addition, many ZIF designs require the use of a separate wedge or secondary cam to apply a normal force to a terminal contacting a conductive trace on a flexible circuit. The use of an extra step to insert a wedge causes misalignments. 
   SUMMARY OF THE INVENTION 
   In accordance with an exemplary form of the present invention a connector assembly is provided offering advantages and alternatives over the prior art in that it is a low insertion force connector designed to assure alignment between a flexible flat cable and the connector, provide a positive lock to assure complete insertion, and provide protection from exposed circuit traces during assembly of the flexible flat cable to the connector. 
   In an exemplary embodiment of the present invention, the low insertion force connector includes an insulative housing, a plurality of terminals mounted in the housing, a flexible flat cable member, a slide member, a wedge member, and a secondary lock member. 
   In accordance with an exemplary form of the present invention, the insulative housing defines a cavity for receiving a connecting end portion of the flexible flat cable member secured between the slide member and wedge member. The terminals are mounted in the housing such that a first end portion extends outside the housing and a second end portion extends into the receiving cavity forming generally parallel rows of first and second contact arms. The connecting end portion of the flexible flat cable has exposed conductors on one side. The connecting end portion is secured between the slide member and the wedge member. The slide member has a cable contact side for contacting a first side of the connecting end portion of the flexible flat cable. A plurality of axially extending first contact arm receiving slots are formed in the cable contact side extending to a mating face of the slide member. Each slot is for receiving the first contact arm of one of the terminals when the slide member along with the wedge member and flexible flat cable are connected to the housing. The slots and exposed conductors are positioned to enable the terminals to electrically contact the exposed conductors when the slide member along with the wedge member and flexible flat cable are connected to the housing. 
   An exemplary form of the present invention incorporates a number of alignment features. These features enable an operator to easily and reliably assemble the connector assembly. 
   In an exemplary form of the present invention, the slide member, the wedge member, and the flexible flat cable member are pre-assembled into a flat cable assembly. The slide member includes a deflectable locking tab and the housing includes a cooperating locking tab socket for releasably retaining the flat cable assembly in the cavity formed in the housing. An exemplary form of the present invention further includes a secondary lock member that is inserted into the locking tab maintaining the locking tab in a locked position and preventing disconnection of the flexible flat cable from the terminals. The locking tab, also known as a Connector Position Assurance, can be pre-assembled to the flat cable assembly, enhancing the insertion process in the final application. The locking tab and socket mechanism of the present invention are capable of providing tactile, visual, and audible feedback indicating that the flat cable assembly is connected and locked into the header cavity. 
   The interaction of the terminals with the slide member and wedge member during assembly eliminates the need for a secondary cam to apply a normal force to the terminal eliminating misalignments caused by an additional cam insertion step. 
   These and other features and advantages of the present invention will become apparent from the following brief description of the drawings, detailed description, and appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1  is a perspective view of a connector assembly according to the present invention; 
       FIG. 2  is a perspective cross-sectional view of one aspect of the present invention; 
       FIG. 3  is a perspective view of a terminal according to the present invention; 
       FIG. 4  is a cross-sectional view of another aspect of the present invention; 
       FIG. 5  is a perspective view of a slide member according to the present invention; 
       FIG. 6  is another perspective view of the slide member according to the present invention; 
       FIG. 7  is a cross-sectional view taken at line  7 — 7  of  FIG. 6 ; 
       FIG. 8  is a perspective view of a wedge member according to the present invention; 
       FIG. 9  is another perspective view of the wedge member of the present invention; 
       FIG. 10  is a perspective view of a flexible flat cable according to the present invention; 
       FIG. 11  is a perspective view of a secondary lock member according to the present invention; 
       FIG. 12  is a perspective cross-sectional view of yet another aspect of the present invention; and 
       FIG. 13  is a perspective cross-sectional view taken at line  13 — 13  of FIG.  12 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the figures wherein like numerals refer to like elements throughout the several views,  FIG. 1  illustrates an exemplary embodiment of connector assembly  10  of the present invention including first connector or header assembly  12 , flat cable assembly  14 , and secondary lock member  16 . Header assembly  12  includes insulative housing  18  and a plurality of conductive terminals  20 . Flat cable assembly  14  includes second connector  21  and flexible flat cable  26 . Second connector  21  includes insulative first connector housing half or slide member  22  and insulative second connector housing half or wedge member  24 . 
   It should be noted that connector assembly  10  has an axis that extends in the direction of insertion of the flat cable assembly  14  into the header assembly  12 . Insulative housing  18  comprises a non-conducting material and has a generally rectangular, elongate shape. As shown in  FIG. 2 , housing  18  includes cable-assembly-receiving cavity  30  defined by top wall  32 , bottom wall  34 , first and second side walls  36 ,  38 , and front wall  40 . Receiving cavity  30  includes opening  42  at mating face  44  opposite front wall  40  for receiving flat cable assembly  14 . A plurality of terminal receiving passageways  46  extend through front wall  40  of housing  18 . Each passageway  46  is sized to frictionally hold a terminal  20 . 
   Top wall  32  of housing  18  includes a plurality of axially extending second contact arm receiving slots  48 , each slot  48  being aligned with, and in communication with, one of the terminal receiving passageways  46 . Housing  18  includes first and second attachment posts  50 ,  52  for attaching housing  18  to circuit board  300  (shown on FIG.  1 ). Axially extending alignment grooves  54  are formed in top wall  32  and bottom wall  34  adjacent to side walls  36 ,  38 . Axially extending alignment groove  56  is formed in the center of top wall  32  and axially extending alignment groove  58  is formed in the center of bottom wall  34 . Axially extending alignment rib  60  is formed in alignment groove  58  formed in top wall  32 . Front wall  40  includes axially extending alignment socket  62  formed therein. Bottom wall  34  includes locking tab receiving sockets  64  formed therein. 
   Terminals  20  are preferably made from a sheet of an electrically conductive material such as metal or metal alloy. As shown in  FIG. 3 , terminal  20  includes first end portion  70  and second end portion  72 . Second end portion  72  includes deflectable first contact arm  74  and second contact arm  76 . First and second contact arms  74 ,  76  extend at a substantially right angle from first end portion  70 . First and second contact arms  74 ,  76  are generally parallel with each other. First contact arm  74  includes end portion  78  having a J-shape with a hook portion  80  of the “J” facing generally toward second contact arm  76  for contacting flexible flat cable  26 . Each second contact arm  76  includes distal end portion  82  having angled surface  84  that faces generally toward first contact arm  74 . 
   As shown in  FIGS. 2 and 4 , header assembly  12  includes each of plurality of terminals  20  mounted within one of the plurality of passageways  46  forming generally parallel rows of first and second contact arms  74 ,  76  within receiving cavity  30 . First end portions  70  protrude outside housing  18  for connection to circuit board  300 . Second contact arms  76  are partially disposed in second contact arm receiving slots  48 . 
   Slide member  22  comprises a non-conducting material. As shown in  FIGS. 5-7 , slide member  22  has an elongate shape adapted to be inserted into receiving cavity  30 . Slide member  22  includes first side  90  for contacting flexible flat cable  26 . A plurality of axially extending first contact arm receiving slots or passageways  92  are formed in first side  90  extending to forward facing mating face  94 . Each slot  92  is for receiving one of the first contact arms  74  when flat cable assembly  14  is connected with header assembly  12 . Slide member  22  includes second side  96  opposite first side  90 . Axially extending alignment ribs  98  are formed along ends of second side  96  of slide member  22 . Deflectable locking tab  100  extends from second side  96  of slide member  22 . Distal end  102  of locking tab  100  extends slightly beyond rearward face  104 . Locking tab  100  includes nibs  106  for engaging locking tab receiving sockets  64 . It should be noted that one or more locking tab could be located on wedge member  24  instead of, or in addition to, slide member  22 . Secondary lock receiving slot  108  is formed under locking tab  100 . Nose portion  110  extends forwardly from mating face  94 . Axially extending alignment rib  112  extends from second side  96  along nose portion  110 . First and second locating post receiving apertures or sockets  114 ,  116  extend through slide member  22 , one socket being formed near each end of slide member  22 . Each locating post receiving socket  114 ,  116  has a V-shape. First and second staking post receiving sockets  118 ,  120  are formed in first side  90 . A V-shaped attachment slot  122  is formed in a forward portion of nose portion  110 . End stop  124  is formed at rearward face  104 . 
   Wedge member  24  is made from a non-conducting material. As shown in  FIGS. 8 and 9 , wedge member  24  has an elongate shape adapted to be inserted into receiving cavity  30  along with slide member  22  and flexible flat cable  26 . Wedge member  24  includes first side  130  for contacting flexible flat cable  26 . Wedge member  24  includes second side  132  opposite first side  130 . Axially extending alignment ribs  134  are formed along each end of second side  132  of wedge member  24 . Second side  132  includes first and a second inclined portion  136 ,  138  for engaging the row of second contact arms  76 . First and second locating posts  140 ,  142  extend from the first side  130  of the wedge member  24 , one locating post being positioned near each end of the wedge member  24 . Obviously, each locating post  140 ,  142  can be located on either the slide member  22  or the wedge member  24  and the corresponding locating post receiving socket  114 ,  116  located on the other of the slide member  22  or the wedge member  24 . First and second staking posts  144 ,  146  extend from the first side  130 . The wedge member  24  has a mating face  148 . A nose portion  150  extends forwardly from the mating face  148 . An attachment post  152  extends from the first side  130  of the nose portion  150 . An axially extending alignment rib  154  extends from the second side  132  along the nose portion  150 . An axially extending alignment groove  156  extends along the center of the second side  132 . The wedge member  24  includes a pair of retaining tabs  158  forming slots for routing the flexible flat cable  26 . 
   As shown in  FIG. 10 , the flexible flat cable  26  has a first side  170  and an opposing second side  172 . The flexible flat cable  26  has a connecting end portion  174  with exposed portions of conductive circuit traces forming electrically conductive contact pads  176  on the first side  170 . First and second locating holes  178 ,  180  are formed in the flexible flat cable  26 . The locating holes  178 ,  180  are positioned to align with the locating posts  142 ,  140  that extend from the first side  130  of the wedge member  24 . First and second staking post receiving holes  182 ,  184  are formed in the flexible flat cable  26 . The staking post receiving holes  182 ,  184  are positioned to align with the pair of staking posts  146 ,  144  that extend from the first side  130  of the wedge member  24 . The flexible flat cable  26  has a cut-out portion  186  at a center of the connecting end portion  174  to provide clearance for the attachment post  152 , the end stop  124 , and the secondary lock member  16 . 
   As shown in  FIG. 11 , the secondary lock member  16  includes an end tab  190  and a locking rod  192  extending perpendicularly from the end tab  190 . An end portion of the locking rod  192  includes a raised platform  194 . 
   The flat cable assembly  14  includes the connecting end portion  174  of the flexible flat cable  26  positioned between the slide member  22  and wedge member  24 . The first side  170  of the flexible flat cable  26  is positioned facing the first side  90  of the slide member  22 . As shown in  FIGS. 12 and 13 , the contact pads  176  are aligned with and face the first contact arm receiving slots  92  on the slide member  22 . The slots  92  provide access for each of the terminal  20  first contact arms  74  to electrically contact the contact pads  176 . Wide contact pads (not shown) may extend across a plurality of slots  92  enabling current flowing through wide contact pads to flow through a plurality of terminals  20 . Each locating post  140 ,  142  of the wedge member  24  extends through a respective locating hole  180 ,  178  of the flexible flat cable  26  into a respective locating post receiving socket  114 ,  116  of the slide member  22  assuring that the first contact arm receiving slots  92  are properly aligned with the contact pads  176 . Each staking post  144 ,  146  of the wedge member  24  extends through a respective staking post receiving hole  184 ,  182  of the flexible flat cable  26  into a respective staking post receiving socket  118 ,  120  of the slide member  22 . The attachment post  152  of the wedge member  24  extends into the attachment slot  122  of the slide member  22 . The locating posts  140 ,  142  and attachment post  152  are wedged into the respective bottoms of each of the “V”s of the sockets  114 ,  116  and the attachment slot  122  providing an interference fit clamping the connecting end portion  174  of the flexible flat cable  26  between the slide member  22  and the wedge member  24 . The slide member  22  substantially covers the contact pads  176  on the connecting end portion  174  of the flexible flat cable  26 . The openings formed by the slots  92  expose the contact pads  176  for contact with the first contact arm  74  of the terminals  20 . 
   The flat cable assembly  14  is connected to the header assembly  12  by inserting the flat cable assembly  14  into the receiving cavity  30  of the housing  18 . As the flat cable assembly  14  is inserted into the receiving cavity  30 , the alignment ribs  98 ,  112  of the slide member  22 , the alignment ribs  134 ,  154  of the wedge member  24 , and the alignment groove  156  of the wedge member  24  engage the corresponding alignment grooves  54 ,  56 ,  58  and the alignment rib  60  of the housing  18  assuring proper alignment between the terminals  20  and the first contact arm receiving slots  92 . The nose portions  110 ,  150  of the slide member  22  and the wedge member  24  are received by the alignment socket  62 . As the flat cable assembly  14  is further inserted into the receiving cavity  30  each of the first contact arms  74  is received in one of the first contact arm receiving slots  92 . The second side  132  of the wedge member  24  abuts against the row of second contact arms  76 , pressing the contact pads  176  of the flexible flat cable  26  against the first contact arms  74  making electrical connection between the terminals  20  and the contact pads  176 . The nibs  106  of the locking tab  100  releasingly engage the locking tab receiving sockets  64  for releasably retaining the flat cable assembly  14  within the receiving cavity  30  of the housing  18 . 
   In an exemplary embodiment, a secondary lock member  16  is inserted into the secondary lock receiving slot  108  formed under the locking tab  100  maintaining the locking tab  100  in a locked position and preventing disconnection of the flexible flat cable  26  from the terminals  20 . 
   This invention has been described with reference to an exemplary embodiment and modifications thereto. Further modifications and alterations may occur to others upon reading and understanding the specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the invention. For example, the locking tab  100  is incorporated in the slide member  22 , but can alternatively be incorporated in the wedge member  24 . Or, for example, locating posts  140 ,  142  are integrally incorporated in the wedge member  24 , but the locating posts can alternatively be incorporated in the slide member  22 . Obviously, distinct locating posts could also be utilized rather than integrally formed posts.