Abstract:
An FPC connector permits downsizing and not exerting residual stress on terminals irrespective of the pivoting position of an actuator while an FPC is not connected. The FPC connector is provided with biasing beams respectively arranged adjacent contact terminals disposed in an insulative housing. The biasing beams are pivotable about support points at intermediate portions thereof. The biasing beams are pivoted by means of pivotal actuator.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a connector for a flat printed circuit or a flat flexible cable which is typically referred to as FPC or FFC. Throughout the disclosure and claims, the wording “FPC” will be used to generally referred to both the flat flexible cable and the flat printed circuit. 
     DESCRIPTION OF THE RELATED ART 
     Conventionally, an FPC connector includes an insulative housing provided with an FPC insertion cavity and a plurality of contact terminals disposed within the insulative housing in a side-by-side relationship with a predetermined pitch. The terminals have contact portions which extend into the FPC insertion cavity. A pivoting actuator is disposed between contacts of the FPC and is designed to apply the necessary contact pressure to cause displacement of contact beams integrally formed with the contact terminals by pivotal motion thereof. Displacement of the contact beams is either for urging the contacts onto the conductors of the FPC or for widening an insertion gap for the FPC. Such FPC connectors are disclosed in U.S. Pat. No. 5,906,498, Japanese Unexamined Patent Publication No. Heisei 11-31561. Japanese Unexamined Patent Publication No. Heisei 10-208822 and Japanese Unexamined Patent Publication No. Heisei 10-214661. 
     As set forth above, displacement of the contact beams integral with the contact terminals by pivotal motion of the pivotal actuator causes resilient deformation of the contact terminals. Therefore, in order to permit pivotal motion of the pivotal actuator without requiring a large activation force, a relatively large arm is required to reduce the force needed to move the actuator so that sufficient force is provided to create an adequate electrical and mechanical engagement between the terminals and the FPC conductors. Therefore, the extra length serves as a hindrance for down-sizing of the FPC connector. 
     On the other hand, a stress is exerted on the contact terminal by pivotal motion of the pivotal actuator. It is possible that during a solder reflow process for mounting the FPC connector on the printed circuit board the stress which remains in the contact terminals can cause the characteristics of the terminal to change in the pressure of the heat. Also, since the force of the actuator is placed between the housing and the terminals, the housing must be larger to accommodate this extra force. 
     SUMMARY OF THE INVENTION 
     The present invention has been designed to solve the shortcomings set forth above. It is therefore an object of the present invention to provide an FPC connector which has a structure permitting down-sizing. 
     Another object of the present invention is to provide an FPC connector which has a structure not exerting residual stress on terminals irrespective of pivoting position of an actuator while an FPC is not connected and to not have the force of the actuator placed between the housing and the terminal thereby permitting former housing downsizing. 
     A further object of the present invention is to provide an FPC connector which has a structure to be easily designed for obtaining he necessary contact pressure. 
     In order to accomplish the above-mentioned objects, a connector releasably coupling, electrically and mechanically, connectors of a flat printed circuit according to the present invention is provided with an insulative housing defining an FPC insertion cavity. A plurality of terminal is held in said housing in a side by side relationship with contact beams extending in the FPC insertion cavity, the terminals each have a support post held to and extending away from the base. Extending laterally from the support post is a pivot point and a contact beam. A plurality of biasing beams arranged adjacent the terminals have a first end, a second end and a fulcrum point. A pivoting actuator including a shaft rotates within the pivot point of the terminals. The shaft has a cam which, when the actuator is in the down or locked position, engages the first end of the biasing beam causing the biasing beams to rotate about their fulcrum points moving the second end into contact with the FPC whereby the FPC is in electrical engagement with the terminals and the FPC is tightly held mechanically between the terminals and the biasing beams. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be understood more fully from the detailed description given hereinafter and from the accompanying drawings of the preferred embodiment of the present invention, which, however, should not be taken to be limitative to the invention, but are for explanation and understanding only. 
     FIG. 1 is a partially cut out perspective view of the preferred embodiment of an FPC connector according to the present invention, which is illustrated in a condition before connection with an FPC; 
     FIG. 2 is a side view of the section of the preferred embodiment of the FPC connector shown in FIG. 1; 
     FIG. 3 is a perspective view of a contact terminal and biasing beam forming the preferred embodiment of the FPC connector of the present invention; 
     FIG. 4 is a partially cut out perspective view of the preferred embodiment of the FPC connector according to the present invention, which is illustrated in a condition where the FPC is connected (the FPC is not shown); and 
     FIG. 5 is a side view of the section of the preferred embodiment shown in FIG. 4 with the FPC in place. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will be discussed hereinafter in detail in terms of the preferred embodiment of the present invention with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be obvious, however, to those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known structures are not shown in detail in order to avoid unnecessary obscurity of the present invention. 
     The preferred embodiment of an FPC connector  10  has an insulative housing  20  formed of an insulative plastic and a pivotal actuator  30 . In the insulative housing  20 , a plurality of contact terminals  40  and biasing beams  50  are loaded in side-by-side relationship at a predetermined pitch. These contact terminals  40  and biasing beams  50  are formed by stamping a thin metal blank. As shown in FIG. 3, adjacent individual contact terminal  40  and individual biasing beams  50  are combined in a scissors-like form. 
     The insulative housing  20  has a top plate  21  and a bottom plate  22 . Between the top plate  21  and the bottom plate  22 , a plurality of terminal receptacle cavities  23  are defined. In FIG. 2, the contact terminals  40  and the biasing beams  50  can be loaded from the rear. In FIG. 2, an FPC insertion cavity  24  opening to the front end is defined for receiving an end portion of an FPC  60  (see FIG.  5 ). 
     Each contact terminal  40  had a base  41  extending along the bottom plate  22  of the insulative housing  20  and a contact beam  42  extending in an upper side of the FPC insertion cavity  24  in cantilever fashion, and a support post  43  integrally interconnecting the base  41  and the contact beam  42 . On the upper end of the support post  43 , a pivot point  44  in the form of a hook portion is provided. The hook portion  44  is located and exposed in the back side of the top plate  21  of the insulative housing  20  so that the pivotal actuator  30  may pivot without interference. 
     The upper end of the contact beam  42  has a thickened portion. This thickened portion is located so that a clearance is formed between the top of the thickened portion and the lower surface of the top plate  21  of the insulative housing  20 . The resulting tapered contact beam  42  may have spring characteristics as elastically deformed toward the top plate  21 . Formed on the lower edge of the tip end portion of the contact beam  42 , is a contact projection  45 . 
     The base  41  of the terminal  40  extends parallel to the upper surface of the bottom plate  22  of the insulative housing  20  so that it may contact with the bottom plate  22  in substantially its entire length. The base  41  has a length projecting rearwardly beyond the bottom plate  22  to form a solder tail  46  lying substantially flush with the lower surface of the bottom plate  22 . 
     The biasing beams  50  are placed adjacent respective of the contact terminals  40 . Each biasing beam  50  includes a second end  53  extending toward the FPC insertion cavity  24  of the insulative housing  20  and a first end  52  extending along the base  41  of the contact terminal  40 . Each biasing beam is pivotably supported by the fulcrum point  51 . As shown in FIGS. 1 and 2, when the biasing beam  50  is in a free condition, it is substantially parallel with the bottom plate  22  of the insulative housing  20 , and the first end  52  is lifted upwardly. As shown in FIGS. 4 and 5, when the first end  52  is substantially parallel with the bottom plate  22 , the second end  53  is lifted upwardly. 
     Fulcrum point  51 , joining the ends  52  and  53 , is bent in a vertical plane to joint both ends in an angled relationship so that the biasing beam  50  may pivot over the base  41 . 
     In the shown embodiment, the biasing beam  50  is formed by stamping a thin metal blank to have electrical conductivity. However, the biasing beam may be formed of an insulative plastic as non-conductive member. 
     The pivotal actuator  30  has a shape and size to be received within an actuator receptacle portion  25  defined on the rear end of the insulative housing  20 . The actuator  30  is formed with a plurality of window openings  31  at positions respectively corresponding to the positions of the hook portions  44  of the contact terminals  40 . By inserting respective hook portions  44  into the window openings  31 , interengagement between the pivotal actuator  30  and the contact terminals  40  is established for permitting pivotal movement of the actuator  30 . The lower edge of the hook portion  44  is formed into a semi-circular engaging edge  47 . A shaft  32  is received within this engaging edge  47 . Thus, the pivotal actuator  30  is pivotable between the substantially vertical position as illustrated in FIGS. 1 and 2 and the substantially horizontal position as illustrated in FIGS. 4 and 5. 
     A cam projection  33  extends from the shaft  32 . An arc-shaped cam face  33   a  is formed on the lower surface side of the cam projection  33 . The arc-shaped cam face  33   a  is formed over the entire width of the pivotal actuator  30 . On the upper edges of the first end  52  of the biasing beam  50  opposing the cam face  33   a , is a recessed portion  54 . This recessed portion provides a smooth sliding surface with cam face  33   a.    
     When the pivotal actuator  30  is pivoted to the vertical position, as shown in FIGS. 1 and 2, the cam projecting piece  33  of the shaft  32  engages abutment  48  at the tip of the hook portions  44  to stop pivotal motion. When the pivoting actuator  30  is pivoted to a substantially horizontal position, as shown in FIGS. 4 and 5, the lower surface of the pivoting actuator  30  contacts the upper edges of the base  41  of the contact terminals  40  to stop pivotal motion. Both side edges of the pivotal actuator  30  engage with engaging portions  27  provided in the side walls  26  of the insulative housing  20  defining the actuator receptacle portion  25  to maintain the pivotal actuator  30  in the substantially horizontal condition. 
     When the pivotal actuator  30  is pivoted to a substantially vertical position, the cam projection  33  is released from the first end  52  of the biasing beam  50  to open the distance between contact  45  and contact tip at the second end  53  on the biasing beam. This opening will facilitate the insertion of the FPC  60  into the connector through the FPC insertion cavity  24  with little or no resistance. 
     After insertion of the FPC  60 , the pivoting actuator  30  is pivoted to the substantially horizontal position. Movement of the cam projection  33  slidingly moves the cam face  33   a  onto the upper edges of the movable beams  52  of the biasing beams  50 . According to this pivotal motion, the first ends  52  are moved downwardly. In conjunction therewith, the second ends  53  move the FPC  60  inserted into the housing toward the contact beams  42  to cause engagement between the contacts  45  of the contact beams  42  and the contacts  61  of the FPC with a contact pressure necessary for establishing electrical connection. Thus, the contacts  45  and the contacts  61  are urged toward each other as if vertically biased by means of springs to reliably establish electrical connection. 
     In the prior art, the beam which engages the FPC is pivoted via elastic deformation which requires a greater force applied to the terminal because the subject invention does not require as much force since there is no elastic deformation. Therefore, the length of the biasing beams  50  can be shorter to permit the depth of the FPC connector in the insertion direction of the FPC to be shorter. In the preferred embodiment, the biasing beam  50  has a length extending backwardly beyond the recessed portions  54  located opposite to the cam face  33   a . However, the length of the movable beams  52  can be shortened to terminate at the position corresponding to the recessed portion. Corresponding to this, the base  41  of the contact terminals  40  can be shortened for downsizing. 
     In the condition where the FPC  60  is not inserted into the FPC connector  10 , at any position of the pivotal actuator  30 , particularly, even if the pivotal actuator  30  is in substantially horizontal position as shown in FIGS. 4 and 5, no stress will be exerted on the contact terminals and the biasing beams  50 . Accordingly, when the FPC connector  10  is fed into a solder reflow process for mounting the FPC connector  10  on the printed circuit board, heating can be performed without stress placed on the terminals which stress combined with heat could change the characteristics of the metal. Accordingly, the spring performance will not be changed. 
     In an alternative embodiment, it is possible to construct the connector by arranging the biasing beams on the side of the top plate  21  of the housing and the contact beams of the contact terminals on the side of the bottom plate  22  of the housing. In such case, the contacts formed at the tip end of the contact beams and the contact formed on the lower side of the FPC are urged toward each other to establish electrical connection with a necessary contact pressure. 
     Although the present invention has been illustrated and described with respect to exemplary embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omission and additions may be made therein and thereto, without departing from the spirit and scope of the present invention. Therefore, the present invention should not be understood as limited to the specific embodiment set out above but to include all possible embodiments which can be embodied within a scope encompassed and equivalent thereof with respect to the feature set out in the appended claims.