Abstract:
A method is provided for connecting a terminal fitting and a flat conductor to achieve a high contact pressure between the terminal fitting and a conductive path. A FFC ( 10 ) has an insulation sheet ( 12 ) adjacent the end stripped to expose a conductor ( 11 ). The FFC ( 10 ) is inserted between first and second squeezing plates ( 22, 23 ) of a terminal fitting ( 20 ). Complimentary recessed/projected portions ( 32, 33 ) are formed on the outer surfaces of a pair of upper and lower press dies ( 30, 31 ) for pressing the terminal fitting ( 20 ). The terminal fitting ( 20 ) is pressed by the press dies ( 30, 31 ). Thus, the FFC  10  and the terminal fitting ( 20 ) are pressed together into a single unit and the squeezing plates ( 22, 23 ) are formed into a zigzag configuration.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a terminal fitting for a flat conductor, a method for connecting a terminal fitting to a flat conductor and a terminal connection apparatus.  
           [0003]    2. Description of the Related Art  
           [0004]    Flexible flat cables (FFCs) and flexible printed circuit boards (FPCs) are referred to generally as flat conductors. The FFC is a ribbon-shaped structure formed from a plurality of parallel conductors and insulation sheets adhered to the front and rear surfaces of the conductors. There are two methods for connecting terminal fittings with the respective conductors near the end of an FFC. The first method connects the terminal fittings while the conductors are left imbedded in the insulation sheets. The second method, on the other hand, strips the insulation sheet off one surface near the end of the FFC, and then connects the terminal fittings with the conductors.  
           [0005]    The second method is disclosed in Japanese Utility Model Publication No. 63-73861 and is shown in FIG. 7 of this application. With reference to FIG. 7, the second method starts with an FFC  1  that has an insulation sheet  2  on the front and rear sides of conductors  3 . A portion of the insulation sheet  2  is stripped for a specified distance from an end of the FFC  1  to expose the front sides of the conductors  3 . The second method then uses a terminal fitting  4  with a connecting portion  5  and a first squeezing plate  6  that extends from the rear end of the connecting portion  5  for connection with a mating terminal fitting (not shown). The terminal fitting  4  also has a second squeezing plate  7  with a base end  7 A that is integral with the base end of the first squeezing plate  6 . The second squeezing plate  7  can be pivoted about the base end  7 A to close and open with respect to the first squeezing plate  6 . Crimping pieces  8  are formed at opposite edges of the leading end of the second squeezing plate  7  and extend toward the first squeezing plate  6 . The terminal fitting  4  and the FFCI are connected by squeezing the conductor  3  between the squeezing plates  6  and  7 .  
           [0006]    The second method merely brings the flat second squeezing plate  7  into surface contact with the conductor  3 . Thus, contact pressure is inevitably low, and the electrical contact is not reliable.  
           [0007]    The present invention was developed in view of the above problem, and an object of the invention is to provide a method and apparatus for connecting a terminal fitting and a flat conductor as well as a terminal fitting which secure a high contact pressure between the terminal fitting and a conductor.  
         SUMMARY OF THE INVENTION  
         [0008]    The invention is directed to a method for connecting a terminal fitting with a flat conductor. The method comprises exposing a conductor near an end of the flat conductor. The method then comprises arranging at least one pair of squeezing plates of the terminal fitting to at least partly oppose each other at the front and rear sides of the exposed conductor. The method further comprises deforming a portion of the squeezing plates into a deformed configuration. The exposed end portion of the flat conductor then is squeezed by the squeezing plates. Thus, the squeezing plates are deformed into a zigzag configuration and the squeezing plates squeeze the exposed end portion of the flat conductor.  
           [0009]    At least one squeezing plate may include at least one holding portion for holding the squeezing plates in a condition where the exposed conductors of the flat conductor are squeezed between the squeezing plates. The holding portion on one squeezing plate may be bent inwardly and crimped into connection with the other squeezing plate. Thus, the terminal fitting and the flat conductor can be connected with a high contact pressure.  
           [0010]    The zigzag configuration defines ridges that may extend at an angle different from 0° or 180° to an extension direction of the flat conductor, and preferably substantially normal to the extension direction. Thus, resistance against a force to withdraw the flat conductor from the terminal fitting is high compared to a terminal fitting with ridges that extend parallel to the extension of the flat conductor.  
           [0011]    The invention also is directed to a terminal connection apparatus for connecting a flat conductor and a terminal fitting. The apparatus comprises arranging means for arranging at least one pair of squeezing plates of the terminal fitting to oppose each other at opposed sides of an exposed conductor near an end of the flat conductor. The apparatus also comprises deformation means for deforming a portion of the squeezing plates into a zigzag configuration and for squeezing or sandwiching the exposed end portion of the flat conductor by the squeezing plates.  
           [0012]    The deformation means may comprise press dies with recessed and projected portions for forming the zigzag configuration. The deformation means preferably deforms the squeezing plates into the zigzag configuration while the squeezing plates squeeze the exposed end of the flat conductor.  
           [0013]    The invention also relates to a terminal fitting for connection with a flat conductor. The terminal fitting comprises at least two squeezing plates that can be opposed to each other at the front and rear sides of an exposed portion of a conductive path of the flat conductor. The squeezing plates comprise a portion with a zigzag configuration that extends at least partly in a direction normal to the plane that contains the exposed portion of the conductive part.  
           [0014]    The terminal fitting may also comprise at least one holding portion on at least one of the squeezing plates for holding the squeezing plates so that the exposed conductors of the flat conductor remain squeezed between the squeezing plates and under high contact pressure.  
           [0015]    The squeezing plates are connected by a bent portion that is folded back at least twice. Additionally, the squeezing plates can be rotated relative to one another about the bent portion.  
           [0016]    These and other objects, features and advantages of the present invention will become apparent upon reading of the following detailed description of preferred embodiments and accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective view showing a state before a terminal fitting and a FFC are connected according to one embodiment of the invention.  
         [0018]    [0018]FIG. 2 is a development of the terminal fitting.  
         [0019]    [0019]FIG. 3 is a side view partly in section showing a state before the terminal fitting and the FFC are connected.  
         [0020]    [0020]FIG. 4 is a side view partly in section showing a state before the terminal fitting is pressed by press dies.  
         [0021]    [0021]FIG. 5 is a side view partly in section showing a state after the terminal fitting and the FFC are connected.  
         [0022]    [0022]FIG. 6 is a perspective view after the terminal fitting and the FFC are connected.  
         [0023]    [0023]FIG. 7 is a perspective view showing a state before a terminal fitting and a FFC are connected according to a prior art method. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    A terminal fitting in accordance with the invention is identified by the numeral  20  in FIGS.  1 - 6 , and is used with a substantially flexible flat cable  10  (hereinafter referred to as FFC  10 ). The FFC  10  has a plurality of substantially parallel conductors  11 , only one of which is shown in FIG. 1. Insulation sheets  12  are adhered to the front and rear surfaces of the conductors  11  so that the FFC  10  defines a flexible ribbon shape. The insulation sheet  12  on the front surface of the conductors  11  is stripped away for a specified distance from the end of the FFC  10 . Thus, the front surfaces of the conductors  11  are exposed adjacent the end of the FFC  10 .  
         [0025]    The terminal fitting  20  is preferably a male terminal fitting and is formed e.g. by processing a conductive metallic plate material by a press. More particularly, the terminal fitting  20  has a tab  21  that is configured to be mated with a mating female terminal fitting (not shown). A first squeezing plate  22  extends from the rear end of the tab  21 . A second squeezing plate  23  initially is substantially parallel to the first squeezing plate  22  and is connected to the first squeezing plate  22  by a bent portion  24  that projects sideways from the rear end of the tab  21 , as shown in FIG. 2. The bent portion  24  is folded back twice during the press-forming of the terminal fitting  20  so that the first and second squeezing plates  22  and  23  oppose each other. Thus, the second squeezing plate  23  can be rotated about the bent portion  24  so that the rear end (right side in FIG. 2) of the second squeezing plate  23  can be moved towards or away from the rear end of the first squeezing plate  22  (refer to FIGS. 1 and 6). Accordingly, the space between the opposed first and second squeezing plates  22  and  23  can be opened and closed.  
         [0026]    The length of the first and second squeezing plates  22 ,  23  is substantially equal to the length of the exposed portions of the conductive paths  11  of the FFC  10 . Additionally, the widths of the first and second squeezing plates  22 ,  23  are slightly wider than the widths of the conductors  11 .  
         [0027]    Crimping pieces  26  are formed at opposite edges of the rear end of the first squeezing plate  22  and extend toward the second squeezing plate  23 . The upper ends of the crimping pieces  26  are formed into edges that are sufficiently sharp to make cuts in the FFC  10 . The crimping pieces  26  preferably are spaced by a distance greater than the width of the corresponding exposed portion of the conductor  11 . The two crimping pieces  26  are substantially opposed to each other in the illustrated embodiment. However, the crimping pieces  26  may be displaced with respect to each other along the longitudinal direction of the first squeezing plate  22 .  
         [0028]    The squeezing plates  22  and  23  of the terminal fitting  20  are left open, as shown in FIGS. 1 and 3, and an end portion of the FFC  10  with the exposed conductors  11  is inserted between the squeezing plates  22  and  23 .  
         [0029]    Next, as shown in FIGS. 4 and 5, the terminal fitting  20  is pressed by press dies  30 ,  31  from above and below the squeezing plates  22 ,  23 . Recessed/projected portions  32 ,  33  are provided on the facing surfaces of the upper and lower press dies  30 ,  31 . The recessed/projected portion  32  includes a large recess  32 A between two small projections  32 B, while the recessed/projected portion  33  includes a large projection  33 A between two small recesses  33 B. The recessed/projected portions  32 ,  33  are substantially complementary to each other to avoid displacement when the terminal fitting  20  is pressed.  
         [0030]    The ridges of the recessed/projected portions  32 ,  33  preferably extend substantially perpendicular to the longitudinal direction of the terminal fitting  20 . Thus, when the terminal fitting  20  and the FFC  10  are connected, the squeezing plates  22 ,  23  are formed into a zigzag configuration  27  with ridges that extend normal to the extension of the FFC  10 . The zigzag configuration  27  extends out of the plane of the exposed conductors  11 . More particularly, interaction with the pressing dies  30  and  31  causes the squeezing plates  22  and  23  and the FFC  10  to assume a zigzag configuration  27 , as shown in FIG. 6. The zigzag configuration  27  is illustrated with sharp ridges. However rounded ridges may also be possible. In the latter case, the recesses  32 A and  33 B and projections  33 A and  32 B are formed accordingly.  
         [0031]    The pressing of the terminal fitting  20  and the FFC  10  by the press dies  30 ,  31  causes the crimping pieces  26  on the first squeezing plate  22  to penetrate through the insulation sheet  12  at opposite sides of the conductor  11  to reach the front side. The pressing operation deforms the squeezing plates  22 ,  23  and squeezes the conductive path  11  to define the zigzag configuration  27 . Further, the pressing operation bends the crimping pieces  26  inwardly and into crimped connection with opposite side edges at the rear end of the second squeezing plate  23 . As a result, the squeezing plates  22  and  23  are connected in their closed state with the exposed portion of the conductive path  11  squeezed therebetween. Thus, the terminal fitting  20  and the FFC  10  are connected with a high contact pressure, and a stable electrical performance is achieved.  
         [0032]    The terminal fittings  20  and portions of the FFC  10  connected to the terminal fitting  20  can be accommodated in cavities of a connector housing (not shown). In this state, a backward pulling force that acts in the direction of the arrow F in FIG. 5 may be exerted on the FFC  10 . In this embodiment, the zigzag configuration  27  has ridges that extend substantially normal to the extension of the FFC  10 . Thus, resistance against a force acting in the direction to withdraw the FFC  10  from the terminal fitting  20  is increased as compared, for example, to a case where the ridges extend parallel to the extension direction of the FFC  10 .  
         [0033]    The present invention is not limited to the above embodiment. For example, following embodiments are also embraced by the technical scope of the present invention as defined by the claims. Further, the technical scope of the present invention is extended to the scope of equivalents as defined by the claims.  
         [0034]    Only one insulation sheet  12  is stripped in the foregoing embodiment. However, both insulation sheets  12  may be stripped according to the present invention.  
         [0035]    Although the terminal fitting  20  is a male terminal fitting in the foregoing embodiment, the present invention may be applied to a female terminal fitting.  
         [0036]    The FFC  10  is used in the foregoing embodiment. However, the flat conductor is not limited to the FFC according to the present invention. A flexible printed circuit board or the like also may be used.  
         [0037]    Although the crimping pieces  26  are formed at the opposite sides of the first squeezing plate  22  in the foregoing embodiment, the holding portions need not be provided at the opposite sides according to the present invention. It may be sufficient to provide at least one holding portion. Further, the holding portion is not limited to the crimping piece  26 , but any holding portion may be adopted provided that it can hold a squeezed state of the flat conductor by the two squeezing plates. For example, the holding portion may be a hook projecting from one squeezing plate toward the other.