Abstract:
The disclosure describes a holder for attachment to a distal end portion of a flat flexible cable (FFC) and directly engaging exposed conductors of the FFC with appropriate terminals of a mating connector. The FFC has opposite side edges and opposite flat surfaces between the side edges. The holder includes a pair of interengaging gripping members for gripping the opposite flat surfaces of the FFC between the opposite side edges thereof. A latch is provided on at least one of the gripping members for latching the holder to the mating connector, with the exposed conductors of the FFC in direct engagement with the terminals of the mating connector.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention generally relates to the art of electrical connectors and, particularly, to a holder for interconnecting or terminating flat flexible circuitry.  
       BACKGROUND OF THE INVENTION  
       [0002]     A flat flexible circuit or cable conventionally includes an elongated flat flexible dielectric substrate having laterally spaced strips of conductors on one or both sides thereof. The conductors often are covered with a thin, flexible protective layer on one or both sides of the circuit. If protective layers are used, the layers are stripped or cutouts are formed therein to expose the underlying conductors where the conductors are to engage the conductors or terminals of a complementary mating connecting device which may be a second flat flexible circuit, a printed circuit board or the terminals of a mating connector. The flat flexible circuit may be a flat flexible cable, a flexible printed circuit board or the like. Hereinafter, such circuitry will be referred to as a flat flexible cable (“FFC”).  
         [0003]     Problems often are encountered in connecting or terminating an FFC because of its low rigidity. If a bare FFC is inserted into a mating connector, insertion resistance often causes deformation or inadequate insertion of the FFC. In order to solve this problem, zero-insertion force (ZIF) connectors have been designed. After insertion of an FFC into a ZIF connector, an actuator is moved to press the FFC against the connector terminals. Unfortunately, such ZIF connectors are unduly complex and excessively large in size.  
         [0004]     An example of a non-ZIF connector is shown in Japanese Patent Application Laid-Open No. 2002-124321, wherein a lock member is attached to a distal end portion of the FFC and is adapted to be engaged by the non-ZIF connector to lock the connector and the FFC in engagement. Such lock members are adapted to support solely the side edges of the FFC. In other words, a greater portion of the FFC (i.e., between its side edges) is not supported by the lock member and therefore remains flexible and unstable. A metallic reinforcement sheet often is laminated to the FFC. The metallic sheet may have a shield function and is usually thin and does into have sufficient strength to prevent deformation of the FFC. If a thick metallic reinforcement sheet of sufficient strength is used, the weight increases significantly with resulting difficulty in handling, and there is a significant cost increase. The present invention is directed to solving this myriad of problems.  
       SUMMARY OF THE INVENTION  
       [0005]     An object, therefore, of the invention is to provide a new and improved holder for an FFC to facilitate interconnecting or terminating the FFC.  
         [0006]     Another object of the invention is to provide an electrical connector assembly for terminating an FFC utilizing the holder of the invention.  
         [0007]     In the exemplary embodiment of the invention, a holder is provided for attachment to a distal end portion of a flat flexible cable (FFC) for and directly engaging exposed conductors of the FFC with appropriate terminals of a mating connector. The FFC has opposite side edges and opposite flat surfaces between the side edges. The holder includes a pair of interengaging gripping members for gripping the opposite flat surfaces of the FFC between the opposite side edges thereof. Latch means are provided on at least one of the gripping members for latching the holder to the mating connector, with the exposed conductors of the FFC in direct engagement with the terminals of the mating connector.  
         [0008]     According to one aspect of the invention, at least one of the gripping members includes positioning means for properly positioning the distal end portion of the FFC in the holder. As disclosed herein, the positioning means is provided by a positioning post on the one gripping member for insertion into a positioning hole in the FFC. Preferably, a pair of the positioning posts are laterally spaced for insertion into a pair of the positioning holes near the opposite side edges of the FFC. The other of the gripping member includes a pair of positioning recesses for accommodating the positioning posts of the one gripping member.  
         [0009]     According to another aspect of the invention, at least one of the gripping members includes a plurality of gripping projections in an array extending between the opposite side edges of the FFC and grippingly engageable with one flat surface of the FFC. The other gripping member includes a flat face engageable with the other flat surface of the FFC behind the gripping projections.  
         [0010]     According to a further aspect of the invention, latch means are provided between the two gripping members to hold the gripping members against the opposite flat surfaces of the FFC. As disclosed herein, the interengaging latch means is provided by a snap-latch means for automatically latching the gripping members together by pressing the gripping members against the opposite flat surfaces of the FFC.  
         [0011]     Other features of the invention include the distal end portion of the FFC having a leading edge, and one of the gripping members includes a lip extending over the leading edge to protect the leading edge.  
         [0012]     The invention also contemplates an electrical connector assembly for terminating an FFC. The assembly includes a connector along with a cable holder as described above.  
         [0013]     Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which:  
         [0015]      FIG. 1  is a perspective view of an electrical connector assembly including a first embodiment of a connector and a cable holder insertable into the connector, according to the invention;  
         [0016]      FIG. 2  is a perspective view of the assembly of  FIG. 1 , in assembled condition;  
         [0017]     FIGS.  3 ( a ), ( b ) and ( c ) are front, top and side elevational views, respectively, of the cable holder according to the first embodiment;  
         [0018]      FIG. 4  is a sectional view through a pair of cable holders at opposite distal ends of an FFC;  
         [0019]      FIG. 5  is an exploded perspective view of the cable holder, including a pair of gripping members with the distal end portion of the FFC therebetween;  
         [0020]      FIG. 6  is a view similar to that of  FIG. 5 , but taken in the opposite direction;  
         [0021]      FIGS. 7-9  are sequential views of assembling the FFC within the cable holder;  
         [0022]      FIGS. 10-14  are different versions of the cable holder, in relation to the area of the holder at the leading edge of the FFC;  
         [0023]      FIG. 15 ( a ), ( b ) and ( c ) are top, front and side elevational views, respectively, of the connector in  FIGS. 1 and 2 ;  
         [0024]      FIG. 16  is an enlarged vertical section taken generally along line  16 - 16  in  FIG. 15 ( b );  
         [0025]      FIG. 17  is a view similar to that of  FIG. 16 , with the connector mounted on a printed circuit board and with the cable holder about to be inserted into the connector;  
         [0026]      FIG. 18  is a view similar to that of  FIG. 17 , with the cable holder and FFC inserted into the connector;  
         [0027]      FIG. 19 ( a ), ( b ) and ( c ) are views similar to that of  FIG. 15 ( a ), ( b ) and ( c ), respectively, but of a second embodiment of the connector;  
         [0028]      FIG. 20  is an enlarged vertical section taken generally along line  20 - 20  in  FIG. 19 ( b ); and  
         [0029]      FIGS. 21 and 22  are views similar to that of  FIGS. 17 and 18 , respectively, but of the second embodiment.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     Referring to the drawings in greater detail, and first to  FIGS. 1 and 2 , the invention is embodied in an electrical connector assembly, generally designated  24 , which includes a first embodiment of a connector, generally designated  26 , for receiving a cable holder, generally designated  28 , which is attached to a distal end portion of a flat flexible cable (“FFC”), generally designated  30 . After the FFC is attached to the holder, the holder and FFC are inserted into a receptacle  32  in the connector in the direction of arrow “A” ( FIG. 1 ). The connector has a latch  34  with a latch aperture  34   a  for receiving a chamfered latch boss  36  on the holder to latch the holder to the connector as seen in  FIG. 2 . When the holder and FFC are fully inserted into the connector, exposed conductors (described hereinafter) on the FFC will engage terminals  37  ( FIG. 1 ) exposed within receptacle  32  of connector  26 .  
         [0031]     Referring to  FIGS. 3, 5  and  6  in conjunction with  FIGS. 1 and 2 , cable holder  28  includes a pair of gripping members, generally designated  38  and  40 , which grip or clamp FFC  30  therebetween. Before proceeding with a description of the details of the gripping members, the drawings show only a distal end portion of the FFC which includes opposite side edges  30   a  and opposite flat surfaces  30   b . The FFC includes an elongated flat flexible dielectric substrate  42  and a reinforcing film  44 . A tab  46  projects outwardly from each opposite side edge  30   a  of the FFC, and a positioning hole  46   a  is formed in each tab. Tabs  46  could be eliminated, and positioning holes  46   a  could be formed inside edges  30   a  of the FFC. As is known in the art, the FFC includes laterally spaced strips of conductors, and the conductors are exposed, as at  40   a  ( FIG. 6 ), for engaging terminals  38  ( FIG. 1 ) of connector  26 . The exposed conductors  40   a  extend along a leading edge  30   c  of FFC  30 , and the exposed conductors are spaced at a selected pitch, such as on the order of 1.0 mm. Reinforcing film  44  may provide a shield to prevent generation of noise.  
         [0032]     Gripping member  38  of cable holder  28  is a substantially rectangular plate member extending the entire width of FFC  30  and including a flat face  38   a  ( FIG. 6 ) which faces the FFC. Gripping member  38  includes a pair of side wings  38   b  having chamfered latch bosses  48  projecting outwardly therefrom. A pair of positioning posts  50  project inwardly from flat face  38   a  immediately inside side wings  38   b . A pair of side walls  52  also project inwardly from flat face  38   a  beneath positioning posts  50  and define spaces  54  therebetween. Latch boss  36  projects outwardly from a flexible latch arm  56  as best seen in  FIG. 5 . The latch arm has a pair of restraining protrusions  56   a  which engage a pair of restraining members  58  to prevent outward over-stressing of the latch arm.  
         [0033]     Still referring to  FIGS. 5 and 6  in conjunction with  FIGS. 1-3 , gripping member  40  has a flat face  40   a  which faces FFC  30  and a pair of side wings  40   b . The side wings have latch apertures  60  for latchingly engaging the chamfered latch bosses  48  of gripping member  38 . A pair of holes or recesses  62  are formed in gripping member  40  immediately inside the side wings  40   b  for accommodating positioning posts  50  of gripping member  38 . Finally, a plurality of gripping projections  64  ( FIG. 5 ) extend in an array (straight line) between side wings  40   b  and, therefore, between the opposite side edges  30   a  of FFC  30 . In essence, gripping projections  64  of gripping member  40  point toward flat face  38   a  of gripping member  38 .  
         [0034]      FIG. 4  simply shows a pair of cable holders  28  attached to opposite distal end portions of an elongated FFC  30 . Each holder  28  includes a pair of gripping members  38  and  40  as described above to grip the distal end portions of the FFC within the two holders. In these sectional views, it can be seen that each gripping member  38  of each holder  28  includes a lip  66  which extends over the leading edges  30   c  of the FFC to protect the leading edges. This protective lip can be seen in  FIG. 6 .  
         [0035]      FIGS. 7-9  show FFC  30  being assembled within cable holder  38  as described above. The distal end  30   c  of FFC  30  is slidably moved in the direction of arrows “B” ( FIG. 7 ) into engagement with flat face  38   a  of gripping member  38  until the leading edge abuts against protective lip  66  as seen in  FIG. 8 . The FFC then is pivoted downwardly in the direction of arrows “C” ( FIG. 8 ) to move positioning holes  46   a  over positioning posts  50  which project from flat face  38   a  of gripping member  38 . The other gripping member  40  then is moved in the direction of arrows “D” ( FIG. 9 ) until latch apertures  60  in side wings  40   b  of gripping member  40  snap into latching engagement about the chamfered latch bosses  48  of gripping member  38 . The cable holder and attached FFC then are ready to be inserted in the direction of arrow “A” ( FIG. 1 ) into receptacle  32  of connector  26 .  
         [0036]      FIGS. 10-14  show various versions of cable holder  28  in the area of the leading edge  30   c  of FFC  30 .  FIG. 10  shows that a distal end  70  of gripping member  38  projects beyond leading edge  30   c  of the FFC. This provides some protection for the leading edge of the FFC.  FIG. 10  shows how griping projections  64  of gripping member  40  positively engage the FFC as the FFC is backed by flat face  38   a  of gripping member  38 . The conductors  48  of the FFC also are exposed in an area generally indicated at  72  in  FIG. 10  for engaging terminals  37  of connector  26 . In other words, gripping member  40  does not cover the exposed conductors. Distal end  70  of gripping member  38  is rounded to provide for smooth insertion of holder  28  into the receptacle of connector  26 .  
         [0037]      FIG. 11  shows a version wherein protective lip  66  on gripping member  38  extends over leading edge  30   c  of FFC  30 . This protective lip prevents the leading edge of the FFC from “stubbing” on any extraneous objects, including portions of connector  26 , when cable holder  28  is handled or inserted into the connector.  
         [0038]      FIG. 12  shows a version wherein a distal end or edge  66   a  of protective lip  66  extends completely beyond the exposed surface of FFC  30 . This adds additional protection for the FFC including leading edge  30   c.    
         [0039]      FIG. 13  shows another version wherein distal edge  66   a  of protective lip  66  extends over the surface of FFC  30  to actually form a groove  74  which encapsulates the extreme end of the FFC along leading edge  30   c . This provides further assurance that the leading edge of the FFC will not abut or stub onto extraneous objects such as the terminals of connector  26 .  
         [0040]      FIG. 14  shows still another version wherein protective lip  76  forms an angled groove  76  for receiving leading edge  30   c  of the FFC. With groove  76  being at an angle, distal edge  66   a  of protective lip  66  does not project beyond the flat surface of the FFC.  
         [0041]     Referring to  FIGS. 15 and 16  in conjunction with  FIGS. 1 and 2 , connector  26  is designed for mounting on a surface  78   a  of a printed circuit board  78  ( FIG. 16 ). The connector includes a dielectric housing  80  mounting terminals  37  within a plurality of terminal-receiving passages  82  in the housing. A pair of metal fitting nails  84  are mounted on the housing and are secured, as by soldering, to appropriate mounting pads on the circuit board. As best seen in  FIG. 16 , each terminal  37  includes a tail portion  37   a  for connection, as by soldering, to an appropriate circuit trace on surface  78   a  of printed circuit board  78 . Each terminal includes a flexible contact arm  37   b  having a contact portion  37   c  exposed within receptacle  32  for engaging a respective one of the exposed conductors  48  ( FIG. 6 ) on FFC  30 . Each terminal includes a body portion  37   d  fixed within the respective terminal-receiving passage  82 .  
         [0042]      FIG. 17  shows cable holder  28  and FFC  30  about to be inserted in the direction of arrow “A” into receptacle  32  of connector  26 .  FIG. 18  shows the holder and FFC fully inserted into the connector. It can be seen in  FIG. 18  that exposed conductors  48  of the FFC are into engagement with contact portions  37   c  of terminals  37 , as contact arms  37   b  of the terminals are flexed, whereby the contact portions are biased against the exposed terminals. The terminals electrically connect conductors  48  of the FFC to the circuit traces on surface  78   a  of printed circuit board  78 . When the cable holder is fully inserted into the connector, latch boss  36  on flexible latch arm  56  of gripping member  38  of holder  28  “snaps” into latch aperture  34   a  of latch  34  on connector  26  to give an audible and/or tactile indication that the holder and the FFC have been fully inserted into the connector.  
         [0043]      FIGS. 19-22  show a second embodiment of a connector, generally designated  26 A, for receiving cable holder  28  and FFC  30 . Like reference numerals have been applied in  FIGS. 19-22  to designated like components described above in relation to the first embodiment of  FIGS. 1-18 . Descriptions of those like components will not be repeated. The basic difference between connector  26 A according to the second embodiment versus connector  26  according to the first embodiment is the orientation of connector  26 A in relation to printed circuit board  78 . In the first embodiment, connector  26  was oriented so that cable holder  28  and FFC  30  were inserted into the connector in a vertical direction as viewed in the drawings, i.e., generally perpendicular to the printed circuit board. In the second embodiment of  FIGS. 19-22 , connector  26 A is configured so that receptacle  32  receives cable holder  28  and FFC  30  in a horizontal direction as viewed in the drawings, i.e., generally parallel to printed circuit board  78  as indicated by arrow “F” in  FIG. 21 . Otherwise, the interengagement and functioning between the cable holder, the FFC and connector  26 A is the same as described above in relation to the first embodiment.  
         [0044]     It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.