Patent Publication Number: US-6341980-B1

Title: Terminal hardware for flat-type conductor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to a terminal hardware used to connect to a terminal of a flat-type conductor. 
     2. Description of Related Art 
     A flexible flat cable (FFC) and a flexible printed circuit (FPC) are known as flat-type conductors. For example, a construction of an FFC is described as follows. Plural strips of conductors are aligned in parallel and covered and pressed by insulating sheets from both upper and lower sides. Thus, the FFC is formed to have a flexible ribbon-shape. There are two methods to connect terminal hardware to each of the conductors of the FFC as described above: a method that connects the terminal hardware to the conductor covered by the insulating sheet, and a method that connects the terminal hardware to the conductor exposed on one side by peeling the insulating sheet of the terminal. 
     The latter method is disclosed in Japanese Utility Model Laid-Open Publication No. Sho.63-73862, for example. As shown in FIG. 11, at the terminal of FFC  1 , a predetermined amount of an insulating sheet  2  on the upper side is peeled, and a conductor  3  is exposed on the upper side. A terminal hardware  4  having a base plate  6  extending from a rear side of a connection portion  5  is provided to be connected to another terminal hardware. Further, a top plate  7  is integrally formed with the base plate  6  so as to face the base plate  6  and to be capable of being opened and closed with respect to the base plate  6 . Claws  8  are provided at opposite side edges of the open end of the top plate  7 . 
     A portion of the exposed conductor  3  is inserted between the base plate  6  and the top plate  7 . The claws  8  pierce the FFC  1  on the lower side and are crimped to opposite side edges of the base plate  6 . Thus, the FFC  1  is sandwiched between the base plate  6  and the top plate  7 , and the top plate  7  is pressed against the conductor  3  to establish connection. 
     However, in the above-described method, since the entire surface of the flat-shaped top plate  7  contacts the conductor  3 , the contact pressure becomes low. Thus, the reliability of electrical contact is poor. 
     Further, when a tension is applied in a longitudinal direction of the FFC  1 , there is a possibility that the claws  8  separate from the FFC  1  (insulating sheet  2 ) and the terminal hardware becomes separated from the FFC  1 , since the claws  8  are caught by the FFC  1  only at a portion where the claws positioned parallel to the tension pierce the FFC. 
     When a terminal hardware is connected to the conductor  3 , which is exposed at a surface, there is a way to avoid the claws  8  piercing the FFC. In this case, the terminal of FFC is formed to have a comb-shape so that each portion where the conductor  3  is exposed is left as a tooth portion. The claws  8  hold the tooth portions of the comb-shape and are crimped thereto to fix the terminal hardware to the terminal of the FFC. However, the terminal hardware  4  is also easily separated from the terminal particularly in this case. 
     The present invention is provided to eliminate the above-described drawbacks. An objective of the present invention is to provide a terminal hardware for a flat-type conductor having a high contact pressure between a conductor and the terminal hardware, and a superior holding force against a tension. 
     SUMMARY OF THE INVENTION 
     To achieve the above and/or other goals, the present invention provides terminal hardware connected to a terminal end of a flat-type conductor having a conductor exposed on one surface. The terminal hardware includes a pair of plates that face each other and receive the conductor therebetween, and a crimping portion that projects from a side edge of one of the pair of the plates and that is bendable and crimpable to a side edge of the other one of the pair of the plates. An elongated projection is provided on one of the pair of the plates facing the exposed surface of the conductor, and is extended in a longitudinal direction of the pair of plates. 
     Further, an engaging and retaining portion, which is configured to engage with and retain the terminal end of the flat-type conductor, is provided on at least one of the pair of the plates and is located forwardly from the elongated projection in a direction in which the terminal hardware extends to engage with the flat-type conductor. 
     According to the features of the present invention, since the elongated projection forcefully presses against and indents the conductor, high contact pressure can be applied and consequently stable electrical connection can be achieved. Further, even when a tension tending to separate the terminal hardware from the flat-type conductor is applied, since an engaging and retaining portion that engages with and retains the conductor is provided, the holding power against the tension can be increased. In addition, the engaging and retaining portion is provided forwardly from the elongated projection in a direction to which the terminal hardware extends to engage with the conductor, the tension applied to the contact portion between the terminal hardware and the terminal end is effectively avoided. 
     The elongated projection can be located at approximately the same position in the longitudinal direction of the pair of plates as a position of the crimping portion. Thus, since the elongated projection forcefully presses against and indents the conductor more effectively, a higher contact pressure can be achieved. Preferably, the crimping portion is a pair of crimping portions projecting from opposite side edges of one of the pair of plates. 
     The engaging and retaining portion can be formed to have an undulating-shape. Accordingly, since the terminal hardware contacts the conductor at broader area, the reliability of the electrical contact can be increased. 
     Further, a piercing portion can be bent at a front end of one of the pair of plates facing the exposed surface of the conductor in a direction to which the terminal hardware extends to engage with the flat-type conductor. The piercing portion pierces the conductor. Accordingly, since the piercing portion pierces the conductor and provides a hook, the holding power against the tension tending to cause separation can be further increased. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein: 
     FIG. 1 is a perspective view illustrating an FFC and a terminal hardware before connection, according to a first embodiment of the present invention; 
     FIG. 2 depicts a blank used to form a terminal hardware according to the first embodiment of the present invention; 
     FIG. 3 is a partial top plan view illustrating the shape of a cut-in projection according to the first embodiment; 
     FIG. 4 is a perspective view from a bottom side illustrating the cut-in projection of FIG. 3; 
     FIG. 5 is a partial cross-sectional view illustrating the FFC and the terminal hardware before connection, according to the first embodiment of the present invention; 
     FIG. 6 is a partial cross-sectional view illustrating the FFC and the terminal hardware after connection, according to the first embodiment of the present invention; 
     FIG. 7 is a perspective view illustrating the FFC and the terminal hardware after connection, according to the first embodiment of the present invention; 
     FIG. 8 is a partial cross-sectional view illustrating the FFC and the terminal hardware before connection, according to a second embodiment of the present invention; 
     FIG. 9 is a partial cross-sectional view illustrating the FFC and the terminal hardware after connection, according to the second embodiment of the present invention; 
     FIG. 10 is a perspective view illustrating the FFC before the connection to the terminal hardware, according to a third embodiment of the present invention; and 
     FIG. 11 is a perspective view illustrating a conventional terminal hardware and a FFC. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the following, embodiments of the present invention are described with reference to the figures. 
     A first embodiment of the present invention is explained with reference to FIGS. 1 through  5 . In FIG. 1, a flexible flat cable (FFC)  10  is shown as an example of a flat-type conductor. Plural strips of conductors  11  are aligned in parallel and spaced at predetermined distances. The plural strips of conductors  11  are covered and pressed by insulating sheets  12  from both upper and lower sides. Thus, the FFC is formed to have a flexible ribbon-shape. Predetermined areas of the insulating sheet of an upper side are peeled off at a terminal end of the FFC  10 . Thus, conductors  11  are aligned while the upper surfaces are exposed. The insulating sheet may be peeled off on both the upper and lower sides. 
     The terminal hardware  20  of the present embodiment is a male terminal hardware and is made of a metal plate having superior conductivity by press molding, for example. The terminal hardware  20  includes a tab  21 , which is configured to be engaged with a female terminal hardware, and a base plate  22  extending from the rear end of the tab  21 . The terminal hardware  20  further includes a top plate  23  facing the base plate  22 . A blank for forming the terminal hardware  20  is shown in FIG.  2 . The blank has the tab  21  and the base plate  22  formed as a single strip. The top plate  23  is provided parallel to the base plate  22  via a folding portion  24 , which projects from a side edge at a proximal end of the tab  21  (i.e. the connection point between the tab  21  and the base plate  22 ). The pair of crimping portions  26  project from opposite side edges of the base plate  22 . The blank may be formed, for example, by punching from the metal plate. When the folding portion  24  is tightly folded twice as shown in FIG. 1, the top plate  23  faces the base plate  22  and can be opened and closed at the rear end (right side in FIG.  1 ). Then, the base plate  22  and the top plate  23  are formed with complementary undulations, for example, by pressing. Finally, the crimping portions are bent toward the top plate  22  to extend upwardly from the base plate. 
     A portion of the top plate  23  faces the base plate  22  so as to be able to be opened and closed and is about the same length as the length of the conductor  11  exposed. Further, the width of the base plate  22  and the top plate  23  are set slightly wider than the width of the conductor  11 . Each of the base plate  22  and the top plate  23  has an undulating portion  25  including two troughs  26  spaced in the longitudinal direction. The undulating portions  25  of the base plate  22  and the top plate  23  are formed so as to engage with each other. Two pairs of crimping portions  28  respectively project upwardly from opposite side edges of the flat portion  27  at the rear end and from opposite side edges of the flat portion  27  between the two troughs  26  of the base plate  22 . The tip of each crimping portion is formed to be sharp. 
     An elongated projection  30  is formed at approximately the center of the width of the flat portion  27  of the top plate  23  between the two troughs  26  extending in the longitudinal direction, and projects downwardly (to the bottom side) therefrom. 
     Further, a cut-in projection  31  is provided on the flat portion  27  at the rear end. In more detail, as shown in FIG. 3, the cut-in projection  31  forms a triangle having an apex directed rearwardly in the plane of the flat portion  27  of the top plate  23 . One side  32  of the triangle, which is perpendicular to the longitudinal direction of the top plate  23 , is formed as a cut, and the flat portion  27  of the triangle is embossed to have a wedge-shaped extending toward the bottom side. As shown in FIG. 4, which is a perspective view from the bottom side, a cut end  33 , which is shaped as a downward triangle, projects in a direction perpendicular to the longitudinal direction of the top plate  23 . In this embodiment, the portions of the base plate  22  and the top plate  23 , in front of the elongated projection  30  in a longitudinal direction of the top and base plates in which the terminal hardware extends to engage with the conductor  11 , constitute an engaging and retaining portion. Thus, the engaging and retaining portion includes the front trough  26  in the undulating portion  25 , the front pair of crimping portions  28  and the cut-in projection  31 . 
     In the following, a connection process of the first embodiment is explained. 
     As shown in FIGS. 1 through 5, the top plate  23  of the terminal hardware is opened upwardly. Under this condition, the FFC  10  is inserted between the base plate  22  and the top plate  23 , while the terminal hardware  20  is aligned with the conductor  11 . Next, the two pairs of the crimping portions  28  provided on the base plate  22  pierce the insulating sheet  12  toward the upper surface. Then, the terminal on the FFC  10  is sandwiched between the base plate  22  and the top plate  23  and is pressed. Then, each of the two pairs of the crimping portions  26  is bent inwardly and is crimped to opposite side edges of the top plate  23 . Accordingly, as shown in FIGS. 6 and 7, the base plate  22  and the top plate  23  hold the conductor  11  therebetween and are closed together to be connected with each other. 
     Since the conductor  11  is sandwiched between and pressed by the base plate  22  and the top plate  23 , the conductor  11  is bent in an undulating-shape having the same shape as the undulating portions  25 . At the same time, the elongated projection  30  provided on the top plate  23  forcefully presses against and indents the conductor  11 , and further the cut-in projection  31  forcefully presses against and bites into the conductor  11 . 
     In other words, since the elongated projection  30  contacts the conductor  11  so as to indent the conductor  11 , high contact pressure can be applied and consequently a stable electrical connection can be achieved. 
     Further, the FFC  10  as described above is used in such a way that the terminal hardware  20  connected to the terminal is stored in a cavity of a connector housing (not shown). In this case, a tension toward the rear end (direction of the arrow in FIG. 6) may be applied to the FFC  10 . However, according to the present embodiment, since the cut-in projection  31  forcefully presses against and bites into the conductor  11 , a hook can be provided against a direction of a tension tending to separate the terminal hardware from the terminal. In addition, the cut end  33 , which is perpendicular to the longitudinal direction of the top plate  23 , is provided in the front side of the cut-in projection  31 . The cut end  33  forcefully presses against and bites into the conductor  11 . Accordingly, the holding power of the FFC  10  against the tension further increases. Thus, the terminal hardware  20  is prevented from easily separating from the terminal of the FFC  10 . 
     Moreover, in the present embodiment, the base plate  22  and the top plate  23  bend the terminal of the FFC  10  in the undulating-shape and engage therewith. In particular, the troughs  26  of the undulating portions  25  can provide a hook. Accordingly, this construction also securely provides the holding power against the tension tending to cause separation. Further, the undulating portion  25  is also effective to provide an efficient amount of contact area between the top plate  23  and the conductor  11 . 
     Next, the second embodiment of the present invention is explained with reference to FIGS. 8 and 9. The terminal hardware  20 A of the second embodiment has a piercing portion  41 , capable of piercing the FFC  10 , at the rear end of the top plate  23 . The piercing portion  41  has a sharp tip and is bent at a right angle toward the base plate  22  side. The other constructions are similar to those of the first embodiment. Therefore, the same reference numerals as in the first embodiment are given to portions having the same functions as that of the first embodiment, and a repetition of the explanation thereof is omitted. Similarly to the first embodiment, the front undulating portions  25 , the front crimping portions  28  and the cut-in projection  31  constitute an engaging and retaining portion. 
     According to the second embodiment, as shown in FIG. 9, when the base plate  22  and the top plate  23  receive the terminal of FFC  10  therebetween and are compressed, the piercing portion  41  provided at the rear end of the top plate  23  pierces a portion of the FFC  10  where both the upper and the lower surfaces of the FFC  10  are covered by insulating sheets  12  toward the lower surface side. 
     In other words, since the piercing portion  41 , which has a width in the direction perpendicular to the tension tending to separate the terminal hardware from the FFC  10 , pierce the FFC  10 , the holding power against the tension to the FFC  10  can be increased. 
     FIG. 10 shows a third embodiment of the present invention. In the third embodiment, the shape of the terminal end of the FFC  10 A is changed. Here, the terminal end of the FFC  10 A is formed in a comb-shape by leaving only portions of insulation where the conductors  11  are provided. 
     When the terminal hardware  20  of the first embodiment is connected to the FFC  10 A, the crimping portions  28  provided on the base plate  22  hold the comb-tooth portion  14  and are crimped to the opposite side edges of the top plate  23  to be fixed with each other. In this case, since the crimping portion  28  is not required to pierce the insulating sheet  12 , the connecting operation of the terminal hardware becomes easier. Further, a possibility of damage to the FFC  10 A can be reduced. 
     Since the base plate  22  and the top plate  23  bend the comb-tooth portion  14  in an undulating-shape and engage therewith, and the cut-in projection  31  forcefully presses against and bites into the conductor  11 , the holding power against the tension tending to separate the terminal from the terminal can be increased. 
     The terminal hardware  20 A of the second embodiment can also be connected to the comb-tooth portion  14  of the FFC  10 A. 
     It is noted that the present invention is not limited by the embodiments explained above using the description and drawings, but the following embodiments; for example, can also be included in the scope of the present invention. Further, in addition to the following, the present invention can be embodied with a variety of changes in so far as it does not depart from the subject of the present invention. 
     (1) The embodiments described above have a top plate provided unitarily and in one piece with the base plate, and has an advantage that the handling of the terminal hardware is convenient and easier. However, it is possible to provide the top plate separately from the base plate. 
     (2) The terminal hardware can be connected with the terminal so that the top plate and the base plate are reversed. In this case, since the base plate contacts the conductor, the elongated projection and the cut-in projection are provided on the base plate. 
     (3) In the first embodiment, the cut-in projection and the undulating portion are provided as engaging and retaining portions to prevent the terminal hardware from separating from the terminal. However, it is possible to provide either one of the cut-in projection and the undulating portion. Alternatively, it is also possible to provide a crimping portion to crimp the terminal hardware to the FFC as an engaging and retaining portion. 
     (4) The piercing portion shown in the second embodiment can be provided at the rear end of the base plate. 
     (5) In the embodiments described above, the widths of the base plate and the top plate are wider than the width of the conductor. However, the widths of the base plate and the top plate can be thinner than the conductor so that the crimping portions pierce the conductor. 
     (6) In the embodiments described above, the tips of the crimping portions have sharp points to pierce the FFC easily. However, when the crimping portion holds the comb-tooth portion as shown in the fourth embodiment, the sharp points are not required. 
     (7) The crimping portions can be provided on the top plate instead of the base plate. Further, the crimping portion can be provided only at one side edge of the top or bottom plate, instead of a pair of them provided on opposite side edges. 
     (8) A female-type terminal hardware can be provided according to the present invention as well as the male-type terminal hardware. 
     (9) The terminal hardware of the present invention can be used with a flat-type conductor, such as a FPC (flexible printed circuit), which has a conductor covered by insulating layers, formed in a flat-shape and exposed at a terminal, as well as the FFC explained in the embodiment described above, as an example. 
     It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to certain embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. 
     The present disclosure relates to subject matter contained in priority Japanese Application No. HEI 11-301327, filed on Oct. 22, 1999, which is herein expressly incorporated by reference in its entirety.