Patent Publication Number: US-7581979-B2

Title: Flat circuit device

Description:
The priority application Number Japan patent application No. 2005-371544 upon which this patent application is based is hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a flat circuit device, especially to the flat circuit device having a conductor of a belt-shape and a covering portion, which can attach a terminal to the conductor by placing the conductor on a bottom wall sandwiched between a pair of crimping pieces of a terminal and by crimping the pair of the crimping pieces. 
   2. Description of the Related Art 
   A motor vehicle is equipped with a variety of electronic devices. The motor vehicle includes a wire harness for supplying electric power of a battery and control signal of a controller to the electronic devices. The wire harness has an electric wire and a connector. The connector has a housing formed with a synthetic resin, and a terminal received into the housing and connected with an end portion of the electric wire. 
   The electronic devices mounted in the motor vehicle have been increasing in accordance with multi-functions requested by users. Accordingly, the wire harness has also been increasing in mass and volume. 
   In order to make the wire harness smaller, the flat circuitry such as FFC (Flexible Flat Cable) and FPC (Flexible Printed Circuit) is proposed as the electric wire. 
   The flat circuit device has a conductor of a belt-shape and a covering portion for covering the conductor. The flat circuit device has the plurality of the conductors extending in parallel each other and the conductors are each insulated with the covering portion. 
   EP1363362 discloses that when a terminal is connected to a conductor of a flat circuitry, the conductor is bent to match with a shape of the terminal and the terminal is connected to the conductor. Thereby, the attachment can be certainly performed, and contact failure of the conductor and the terminal can be avoided. 
   A method of connecting the terminal to the conductor disclosed in EP1363362 requires a metal mold to form the conductor so as to match the shape of the terminal, and a metal mold for crimping the terminal to the conductor. Accordingly, a cost of connecting the terminal tends to increase. 
   Also, as shown in EP1363362, the conductor may be attached to the terminal by placing the conductor on a pair of crimping pieces of the terminal and crimping the crimping pieces without change in shape by a terminal attached to the conductor. The conductor is formed into a flat shape and changes easily. Therefore, even a minimal force changes the conductor to a complex shape easily. For this reason, the terminal can not certainly connect to the conductor surely so that the conductor is changed into a shape matched to the crimping pieces. 
   SUMMARY OF THE INVENTION 
   The present invention provides a terminal which can be mounted on a conductor of a flat circuit device without an increase in cost, and provides a mounting method thereof. 
   According to a first aspect of the present invention, a flat circuit device includes a belt-shaped conductor, and a covering portion for covering the conductor. The conductor has a groove along a longitudinal direction thereon. The conductor of the flat circuit device is attached to a terminal by placing the conductor on a bottom wall sandwiched between a pair of crimping pieces of the terminal and crimping the pair of the crimping pieces. 
   With the construction described above, the groove is arranged on the conductor along the longitudinal direction of the conductor. When the pair of the crimping pieces is crimped, pressure is applied to the conductor in a width direction of the conductor. Thereby, the conductor is bent along the groove by applying the pressure. Also, a bent portion of the conductor approaches to the bottom wall. Thus, deformation of the conductor can be controlled by forming the groove on the conductor, and the conductor can be changed to match with a shape of the terminal and the bottom wall. 
   Preferably, the groove is arranged at the center of the conductor in a width direction. 
   With the construction described above, when the pair of the crimping pieces is crimped, the conductor is bent along the groove by applying the pressure. Thus, since the conductor is symmetrically bent along a line passing through the center of the conductor in the longitudinal direction, the conductor can be prevented from being bent to one side of the pair of the conductor crimping pieces. 
   Preferably, at least a pair of the grooves is symmetrically arranged on the conductor along a line at the center in the width direction extending in a longitudinal direction. 
   Preferably, slope faces sloped in a direction away from the bottom wall are arranged on both ends in the width direction of the conductor. 
   With the construction described above, the conductor can be bent along the groove toward the bottom wall and the crimping pieces by having the slope face. 
   The above and other objects and features of this invention will become more apparent from the following description taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing a terminal of the present invention and a FFC mounted on the terminal; 
       FIG. 2  is a sectional view taken along the line II-II of the terminal and the FFC of  FIG. 1 ; 
       FIG. 3  is a perspective view showing that the conductor is placed on a bottom wall between a pair of conductor crimping pieces of the terminal of  FIG. 1 ; 
       FIG. 4  is a perspective view showing that the conductor crimping pieces of the terminal of  FIG. 3  is crimped; 
       FIG. 5A  is a partly top view of the FFC shown in  FIG. 1 ; 
       FIG. 5B  is a partly front view of the FFC shown in  FIG. 1 ; 
       FIG. 6  is one example of a crimping device which crimps the terminal and conductor of  FIG. 1 ; 
       FIG. 7  illustrates that the terminal and the FFC are placed on an anvil of the crimping device shown in  FIG. 6 ; 
       FIG. 8  is a partly enlarged frond view of  FIG. 7 ; 
       FIG. 9  illustrates that the anvil of  FIG. 6  and a crimper approach each other; 
       FIG. 10  is a partly enlarged front view of  FIG. 9 ; 
       FIG. 11  illustrates that the terminal and the conductor of the FFC is sandwiched between the anvil of  FIG. 6  and the crimper; 
       FIG. 12  illustrates the terminal attached to the FFC shown in  FIG. 11 ; 
       FIG. 13  illustrates problem that a slope face is not arranged on the conductor  4 ; 
       FIG. 14  is a partly top view of another embodiment of the FFC  2 ; and 
       FIG. 15  is a partly top view of another embodiment of the FFC  2 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In the following, embodiments of the present invention are explained with reference to FIGS. 
   A FFC (Flexible Flat Cable)  2  as the flat circuit device, as shown in  FIG. 1 , has a plurality of conductors  4  and a covering portion  5  for covering the conductors  4 . The FFC  2  has a belt-shape. 
   The conductors  4  are made of a conductive metal containing at least copper or a copper alloy. The conductors  4  have a rectangle cross-section and extend parallel each other. 
   The covering portions  5  are made of a synthetic resin insulator having a belt-shape and cover separately the plurality of the conductors  4  for electric insulation. The FFC  2  has the plurality of the conductors  4  at an end thereof where the covering portions  5  are removed. The conductors  4  are separated with silts  7  each other. 
   The flat circuit described in the present invention shows the flat circuit has a conductor of a belt shape and a insulating covering portions covering the conductor. 
   A terminal  6  is formed by bending a conductive sheet metal. As shown in  FIG. 1 , the terminal  6  has an electric contact portion  9  for connecting a mating terminal and an electric connection portion  10  for crimping the conductors  4  of the FFC  2 . 
   The electric contact portion has a rectangular-section tube  11  and a spring, not shown, received in the tube  11 . The tube  11  has a square-section in  FIG. 1 . When an insertion pieces such as a male tab of a mating terminal is inserted into the tube  11 , the spring stresses the male tab toward an inner wall of the tube  11  to hold the male tab. Thereby, the electric contact portion  9  electrically and mechanically connects the mating terminal. 
   As shown in  FIG. 2 , the connection portion  10  has a bottom wall  12  with a circular-section, a pair of conductor crimping pieces  13  and a pair of clad crimping pieces  14 . The bottom wall  12  is connected to an outer wall of the tube  11 . The conductor  4  disposed at the end of the FFC  2  is placed on the bottom wall  12 . 
   The pair of the conductor crimping pieces  13  forms crimping pieces in the present invention. The conductor crimping pieces  13  are disposed at the center of the bottom wall  12  and upstanding at both sides in a direction of width of the bottom wall  12 . 
   As shown in  FIG. 4 , the ends of the conductor crimping pieces  13  are bent toward the bottom wall  12  to sandwich the conductor  4  of the FFC  2 . 
   The clad crimping pieces  14  are disposed opposite to the electric contact portion  9  with respect to the bottom wall  12 . The clad crimping pieces  14  are disposed in the direction of width of the bottom wall  12  and upstanding at the both ends thereof. As shown in  FIG. 4 , ends of the clad crimping pieces  14  are bent toward the bottom wall  12  to sandwich the covering portion  5  of the FFC  2 . 
   As shown in  FIG. 5 , a groove  4   a  with a V-shaped section is disposed in the conductor  4  along a longitudinal direction Y 1  of the conductor  4 . The groove  4   a  is disposed at the center in a width direction Y 2  of the conductor  4 . The groove  4   a  is disposed in an area covered by the covering portion  5  as well as the conductor  4 . The groove  4   a  is formed by pressing a V-shaped die. As shown in  FIG. 8 , the groove  4   a  is arranged on a surface away from the bottom wall  12  in condition that the conductor  4  is placed on the bottom wall  12 . As shown in  FIGS. 5B and 8 , in condition that the conductor  4  is positioned on the bottom wall, slope faces  4   b  are disposed in the both ends in the width direction Y 2  of the conductor  4 . The slope faces  4   b  are sloped in a direction away from the bottom wall  12 . 
   For example, the ends of the conductor crimping pieces  13  the terminal  6  is bent toward the bottom wall  12  to sandwich the conductor  4 , and the ends of the clad crimping pieces  14  are bent toward the bottom wall  12  to sandwich the covering portion  5  by a crimping device  1  shown in  FIG. 6 . As shown in  FIG. 4 , the terminal  6  crimps the conductor  4  of the FFC  2  and the covering portion  5  by the crimping pieces  13 ,  14  of the crimping device  1 . Thereby, the terminal  6  is attached to the end of the FFC  2 . 
   As shown in  FIG. 6 , the crimping device  1  has a main body (not shown), a crimping portion  15  as a way of crimping, and an air cylinder  17  as a drive source. The main body is installed on a floor of a factory. 
   The crimping portion  15  has an anvil  19  and a crimper  20 . The anvil  19  is fixed to the main body and receives the terminal  6  thereon. 
   The crimper  20  is supported with the main body and is opposed to the anvil  19  and can come close to or off from the anvil  19 . The crimper  20  has a slit  20   a  tapered toward the air cylinder  17 . 
   When the anvil  19  and the crimper  20  are separated each other, the terminal  6  and an end portion of the FFC  2  are placed on the anvil  19 . The anvil  19  and the crimper  20  come close to each other to sandwich the terminal  6  and the end portion of the FFC  2  and to crimp them with the crimping pieces  13  and  14 . 
   The air cylinder  17  as a drive source has a cylinder  23  and a retractable rod  24  from the cylinder  23 . The cylinder  23  is attached to the main body. The rod  24  is attached to the crimper  20 . The air cylinder  17  is disposed on area where the crimper  20  comes close to the anvil  19  when the rod  24  is expanded from the cylinder  23 , and where the crimper  20  comes off from the anvil  19  when the rod  24  is reduced to the cylinder  23 . 
   A method of connecting the terminal  6  to the conductor  4  is described below. As shown in  FIG. 7 , the anvil  19  and the crimper  20  are separated each other. The terminal  6  is placed on the anvil  19 . The conductor  4  exposed from the end portion of the FFC  2  is placed on the bottom wall  12  of the terminal  6 . At this time, the bottom wall  12  is positioned closer to the slope face  4   b  of the conductor  4  than the groove  4   a  of the conductor  4 . 
   Thereafter, the rod  24  of the air cylinder  17  is extended. As shown in  FIG. 9 , the crimper  20  approaches to the anvil  19 . The pair of the crimping pieces  13  is sandwiched between the slit  20   a  arranged on the crimper  20 . As described above, width of the slit  20   a  decreases with distance from the anvil  19 . Thereby, when the crimper  20  approaches to the anvil  19 , a deforming force K ( FIG. 10 ) from a surface of the groove  20   a  of the crimper  20  is applied to the pair of the crimping pieces  13 . As a result, the pair of the crimping pieces deforms by approaching to each other. 
   Also, the deforming force K is applied to the conductor  4  through the pair of the crimping pieces  13 . As shown in  FIG. 10 , when the deforming force K is applied to the conductor  4  in the width direction Y 2 , the conductor  4  is bent along the groove  4   a  arranged at the center of the conductor  4  and deformed. Thereby, a bent portion of the conductor  4  approaches to the bottom wall  12 . As shown in  FIG. 11 , the terminal  6  and the conductor  4  of the FFC is sandwiched between the anvil  19  and the crimper  20 , and the crimping pieces  13  and  14  are crimped. Thereby, the terminal  6  is attached to the FFC  2 . Finally, as shown in  FIG. 12 , the conductor  4  is fixed to the terminal  6  by applying press in condition that the conductor  4  is arranged in close contact with the bottom wall  12 . 
   When the rod  24  of the air cylinder  17  is reduced, the anvil  19  and the crimper  20  are separated each other. Thereafter, the terminal  6  on the anvil  19  shown in  FIG. 12  is removed. In common with the above described process, the terminal  6  is attached to the FFC  2  by placing the terminal  6  on the anvil  19 , and by positioning the conductor  4  of the FFC  2  on the bottom wall  12  of the terminal  6 . 
   According to the above FFC  2  of the present invention, by forming the groove  4   a , deformation of the conductor  4  can be controlled. Furthermore, the conductor  4  can be deformed depending on deformations of the conductor crimping pieces  13  and the bottom wall  12 . As shown in  FIG. 12 , ultimately, the conductor  4  can be changed without gaps between the conductor  4  and the conductor crimping pieces  13 , and between the conductor and the bottom wall  12 . Therefore, it is not required to change a shape of the conductor  4  based on the terminal  6  by using a die. The conductor  4  can be attached to the terminal  6  by crimping the conductor crimping pieces  13 . Accordingly, increase of a die used in attaching the terminal  6  to the conductor  4  can be prevented. In addition, the conductor  4  can assuredly be attached to the terminal  6  with a low cost. 
   Furthermore, the conductor  4  can be symmetrically bent along the longitudinal direction Y 1  and through the center in the width direction Y 2  without deformation of the conductor  4  by being bent to one side of the pair of the conductor crimping pieces  13 . 
   Additionally, the conductor  4  has the slope face  4   b . The slope faces  4   b  are arranged on the both ends in the width direction Y 2  of the conductor  4 , and are sloped in a direction away from the bottom wall  12 . As shown in  FIG. 13 , when the conductor  4  not arranging the slope face  4   b  is placed on the bottom wall  12 , a lower portion of the both ends of the conductor  4  near the bottom wall  12  is sandwiched with the conductor crimping pieces  13 . However, an upper portion of the both ends of the conductor  4  is not sandwiched with the conductor crimping pieces  13 . Thereby, when the deforming force K is applied to the conductor  4  in the width direction Y 2 , first the deforming force K is applied to the lower portion of the both ends of the conductor  4 . However, then, the deforming force K is not applied to the upper portion of the both ends of the conductor  4 . As a result, the conductor  4  can not be bent along the groove  4   a  as shown in  FIG. 10 . Thereby, as shown in a dotted line of  FIG. 13 , the conductor  4  could be bent in a direction away from the bottom wall  12 . 
   Therefore, as described above, by arranging the slope face  4   b  on the both ends of the conductor  4 , the deforming force K can be applied to both the upper portion of the both ends of the conductor  4  and the lower portion of the both ends of the conductor  4 . As a result, the conductor  4  can be sandwiched with the conductor crimping pieces  13 . Consequently, as shown in  FIG. 10 , the conductor  4  can be certainly bent along the groove  4   a , and attached to the terminal  6 . 
   In the embodiment of the present invention, one groove  4   a  is arranged at the center of the conductor  4  in the width direction Y 2 . However, the present invention is not limited thereto. As shown in  FIG. 14 , a pair of the grooves  4   a  can be symmetrically arranged along a line L of the center of the conductor  4  in the longitudinal direction Y 1 . In addition, the groove can be added to the pair of the grooves the conductor  4 . Furthermore, as shown in  FIG. 15 , three grooves  4   a  can be arranged on the conductor  4 . One of the grooves  4   a  can be placed on the center of the conductor  4  and the others of the grooves  4   a  can be placed on symmetric position along the line L. 
   Therefore, the conductor  4  can be bent along the grooves  4   a  shown in  FIGS. 14 and 15 , and be changed without deformation by being bent to one side of the pair of the conductor crimping pieces  13 . 
   Additionally, in the embodiment of the present invention, the groove  4   a  is formed with a V-shaped section. However, the present invention is not limited thereto. The groove  4   a  can be formed with various shapes. That is, it is only required that the groove  4   a  is disposed along the longitudinal direction Y 1  of the conductor  4 . 
   On the other hand, when bending to one side is no problem, it is not required to arrange the groove  4   a  at the center in the width direction Y 2  or to symmetrically dispose a pair of the groove  4   a  along the center line of the conductor. Thus, the groove  4   a  can be arranged anywhere in the conductor  4  along the longitudinal direction Y 1 . 
   The embodiment of the present invention is only exemplary and not limited thereto. Modifications are possible within the scope of the present invention.