Abstract:
When the movable member ( 30 ) is at the open position, the cam portion ( 33 ) of the movable member ( 30 ) is out of contact with the pressure receiving portion of a lever arm ( 21 ), making it possible to insert a flat cable into the connector on the contact side. When the movable member ( 30 ) is at the closed position, the cam portion ( 33 ) comes into contact with the pressure receiving portion that consists of a shoulder ( 21 D) and a concave indentation ( 21 B). While the movable member ( 30 ) is moving to the closed position, the cam portion ( 33 ) pushes the shoulder ( 21 D) to provide the pressure receiving portion with the highest pressure. When the movable member ( 30 ) reaches the closed position, the cam portion ( 33 ) rests in the concave indentation ( 21 B) while maintaining a pressure less than the highest pressure.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to electrical connectors for flat cables.  
         [0003]     2. Description of the Related Art  
         [0004]     Japanese Patent No. 3047862 discloses a connector of this type. As shown in FIGS.  5 (A) and  5 (B), this connector includes a plurality of terminals  51  arranged in the direction perpendicular to the drawing sheet. The terminal  51  has upper and lower arms  52  and  53  which are connected by a linking section  54 , forming a substantially H-shape. The lower arm  53  is in contact with the bottom wall  56  of a housing  55 , with one of its ends  57  engaged with the housing  55 . The other end forms a connection section  58  outside the housing  55 . The upper arm  52  is made flexible and has a contact portion  52 A at one end to cooperate with the contact portion  53 A of the lower arm  53  for holding a flat cable P between them for contact. See  FIG. 5 (B). At the other end, it has a corner portion  52 B to receive a force from a movable member  59  when the movable member  59  rotates from the position of  FIG. 5 (A) to the position of  FIG. 5 (B). Consequently, the contact portion  52 A is pressed onto the flat cable P.  
         [0005]     The movable member  59  has a corner portion  59 A to serve as a cam for the corner portion  52 B. When the corner portion  59 A moves past the corner portion  52 B, it makes a click sound and presses the upper arm  52  to keep the contact pressure of the contact portion  52 A.  
         [0006]     There is a demand for a low-profile connector of this type. Also, it is required to provide a sufficient click sound or sensation to indicate that the movable member is brought to such a position that a satisfactory contact pressure is provided between the terminal and the flat cable.  
         [0007]     However, the above connector fails to meet both the requirements at the same time.  
         [0008]     The degree of click sensation is large when the angle between the two straight sections of the corner portion  52 B is large because the contact position with the movable member changes quickly. However, if the angle is too large, no low-profile connector is provided. Also, when the movable member  59  moves past the corner portion  52 B, the upward pressure is lowered too quickly to provide satisfactory contact pressure between the contact portion  52 A and the flat cable. In other words, when the satisfactory contact pressure is maintained, the angle of the corner portion is too small to provide a satisfactory click sensation.  
       SUMMARY OF THE INVENTION  
       [0009]     Accordingly, it is an object of the present invention to provide a low-profile flat cable electrical connector capable of providing a satisfactory click sensation and maintaining a high contact pressure between the terminal and the flat cable.  
         [0010]     The invention relates to a flat cable electrical connector, which includes a housing; a plurality of terminals made of sheet metal and arranged in the housing at predetermined intervals in a first direction perpendicular to the sheet metal; and a movable member rotatable between an open position and a closed position and having a cam portion. Each of the terminals includes a lever arm extending in a second direction in which a flat cable is inserted into the electrical connector and having a fulcrum at a middle point thereof. The lever arm has a pressure projection for pressing down the flat cable at an end thereof and a pressure receiving portion at the other end for receiving a pressure from the cam portion of the movable member to flex in the same plane as that of said terminal, thereby producing a pressure between the contact projection and the flat cable.  
         [0011]     The cam portion has such a shape that it is out of contact with the pressure receiving portion of the lever arm when the movable member is at the open position, thereby making it possible to insert the flat cable and in contact with the pressure receiving portion when the movable member is at the closed position. The pressure receiving portion has a shoulder and a concave indentation continued from the shoulder so that when the movable member moves to the closed position, the cam portion provides the pressure receiving portion with a highest pressure and when the movable member reaches the closed position, the cam portion rests in the concave indentation while maintaining a pressure that is lower than the highest pressure.  
         [0012]     When the cam portion reaches the shoulder of the pressure receiving portion, the lever arm receives the highest pressure from the cam portion. A large degree of click sensation is provided at the entry of the concave indentation due to the sharp slope of the concave indentation. At the closed position of the moving member, the cam portion abuts against the upward slope of the concave indentation, maintaining a high pressure on the pressure receiving portion.  
         [0013]     The cam portion may have an elongated circular or elliptic cross-section and the concave indentation may have such a curved shape as to fit to a shape of said cam portion. The curved portion of the elongated circular or ecliptic cam makes the contact position with the pressure receiving portion move smoothly and the concave curve of the concave indentation makes stable the final position of the cam at the closed position.  
         [0014]     The terminal further comprises an attaching arm extending in parallel with said lever arm and a linking section for connecting said lever and attaching arms at their middle point where said fulcrum is situated. It is preferred that the attaching arm has an attaching section to be attached to said housing adjacent to said linking section.  
         [0015]     When the movable member moves to the closed position, the pressure receiving portion of the lever arm receives a force from the cam portion of the movable member so that the linking section receives a large bending moment which is secured by the attaching section.  
         [0016]     The housing has a bottom wall, an upper wall and an island provided between said bottom and upper walls to form a space between said bottom wall and said island into which said attaching section is press fitted. Consequently, the attaching section is secured without increasing the height of the connector. The island may be provided near the linking section.  
         [0017]     The attaching arm may have a contact projection at a position corresponding to the pressure projection of the lever arm. Also, it may have a connection section projecting from the housing, such that when the connector is provided on a circuit board, the connection section comes into contact with a circuit trace of the circuit board.  
         [0018]     As has been described above, according to the invention, the sharp slop of the pressure receiving portion from the shoulder to the front edge of the concave indentation produces a large degree of click sensation. In addition, the movable member abuts against the upward slope at the rear portion of the concave indentation and rests at a stable position while maintaining a large degree of pressure to the pressure receiving portion. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is a sectional view of an electrical connector according to an embodiment of the invention, in which the movable member is at the open position;  
         [0020]      FIG. 2  is a sectional view of the electrical connector, in which the movable member is moving from the open position to the closed position;  
         [0021]      FIG. 3  is a sectional view of the electrical connector, in which the movable member is at the closed position;  
         [0022]      FIG. 4  is a section view of an electrical connector according to another embodiment of the invention;  
         [0023]      FIG. 5 (A) is a sectional view of a conventional connector, in which the movable member is at the open position; and  
         [0024]      FIG. 5 (B) is a sectional view of the conventional connector, in which the movable member is at the closed position. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     An embodiment of the invention will now be described with reference to  FIGS. 1-4 .  
         [0026]     In  FIG. 1 , a plurality of terminals are arranged at predetermined intervals in the first direction perpendicular to the drawing sheet. A housing  10  is made of a dielectric material so as to provide a substantially rectangular form which has a plurality of slits  11  between an upper wall  10 A and a bottom wall  10 B of the housing  10  for receiving the terminals. The thickness of the slit  11  is substantially equal to the thickness of the terminal which is inserted into the housing from right to left. The slits  11  are arranged at predetermined intervals in the first direction and extend laterally through the housing  10 .  
         [0027]     A cable receiving cavity  12  is provided in the left half of the housing  10  so as to communicate with the slits  11 . The height of the cable receiving cavity  12  is slightly greater than the thickness of a flat cable to be inserted. The cable receiving cavity  12  has tapered opening  12 A to facilitate the insertion of a cable. An open section  13  is provided in the upper right side half of the housing  10  so as to communicate with the slits  11  and receive a movable member. An island  14  is provided in the slit  11  between the upper wall  10 A and the bottom wall  10 B to link opposite inner walls of the slit  11 .  
         [0028]     The terminal  20 , which is to be inserted into the housing  10 , is made so as to maintain the flat surfaces of metal sheet. As shown in  FIG. 1 , it has an upper lever arm  21  and a lower attaching arm  22 . Both the lever arm  21  and the attaching arm  22  extend laterally in substantially parallel and are housed in the upper and lower portions of the slit  11 , respectively, and connected with a linking section  23  at the middle position.  
         [0029]     The lever arm  21  has a pressure projection  21 A at the left end and a curved indentation  21 B on the right side lower edge. A shoulder  21 D is provided between the curved indentation  21 B and a straight edge  21 C to form, together with the curved indentation  21 B, a pressure receiving portion for receiving a pressure from a cam portion. It is noted that there is a space between the upper edge  21 E of the lever arm  21  and the upper wall  10 A of the housing  10 .  
         [0030]     Similarly, the attaching arm  22  has a contact projection  22 A at the left end at a position corresponding to the pressure projection  21 A. A pedestal-shaped fixing portion  22 B is provided to the left of the linking section  23 , which is press fitted into a space of the slit  11  between the island  14  and the bottom wall  10 B of the housing  10 .  
         [0031]     The attaching arm  22  has a stopper projection  22 C, a concave indentation  22 D, and a connection section  22 E to the right of the linking section  23 . The concave indentation  22 D has an arc shape and is situated at a position corresponding to the concave indentation  21 B of the lever arm  21 . The connection section  22 E has a lower edge that is slightly lower than the bottom wall  10 B of the housing  10  and, when the connector is mounted on the circuit board, soldered to the circuit trace.  
         [0032]     The movable member  30  is made of a dielectric material so as to extend in the first direction in substantially the same range as the housing  10 . It has a plurality of slits  31 , an upper manipulation section  32 , and a lower cam section  33 . It is made rotatable between the open position in  FIG. 1  and the closed position in  FIG. 3 . It is assembled with the housing  10  such that the slit  31  receives the right section of the lever arm  21  while the cam portion  33  is abutted on the upper edge of the attaching arm  22  such that its left portion is adjacent to the stopper portion  22 C and its right portion is over the concave indentation  22 D of the attaching arm  22 . The major diameter of the cam portion  33  is made greater than the distance between the concave indentations  21 B and  22 D of a terminal  20 .  
         [0033]     The connector according to the invention is assembled and used as follows. 
    (1) The terminals  20  are incorporated in the housing  20 . Each terminal  20  is inserted into the slit  11  from right to left. The attaching section  22 B is press fitted into a space between the bottom wall  10 B and the island  14  while the front edge of the connection section  22 E abuts against the rear end of the housing  10  so that the terminal  20  is secured at a predetermined position.     (2) The movable member  30  is assembled such that it stands uprightly at the open position in  FIG. 1 . It is moved to the left such that the rear portion of the lever arm  21  enters the slit  31  thereof. Consequently, the cam portion  33  is housed in the concave indentation made between the stopper portion  22 C and the concave indentation  22 D. This completes the assembling of the connector.     (3) In use, the connector is provided above a predetermined circuit board (not shown). The connection section  22 E is soldered to the corresponding circuit trace while the housing is attached to the circuit board with screws or reinforcing fasteners.     (4) A flat cable C or flexible board is inserted into the cavity  12  and, then, as shown in  FIG. 2 , the movable member  30  is rotated in the clockwise direction. As a result, the cam portion  33  is changed from the horizontal position in  FIG. 1  to the vertical position in  FIG. 2 , so that the terminal  20  is pressed upwardly at the shoulder  21 D of the pressure receiving portion to flex upwardly the right side portion of the lever arm  21  on the right side of the linking section  23 . Consequently, the left side portion of the lever arm  21  is flexed downwardly with the linking section  23  as a fulcrum. Thus, the flat cable C is pressed downwardly by the pressure projection  21 A of the lever arm  21  so that it is held between the pressure projection  21 A and the contact section  22 A of the attaching arm  22 . As a result, the flat cable C is connected electrically with the terminal through the contact projection  22 A and/or the pressure projection  21 A.     (5) The pressure on the pressure receiving portion of the terminal  20  becomes the highest where the cam portion  33  abuts against the shoulder  21 D made by the lower straight edge of the lever arm  21  and the concave indentation  21 B.     (6) When the movable member  30  is further rotated, as shown in  FIG. 3 , the cam portion  33  rests in the concave indentation  21 B past the shoulder  21 D. The pressure on the terminal abruptly drops at the entry side of the concave indentation  21 B due to the sharp slope so that the operator receives a high degree of clicking sensation. When the cam portion  33  is housed in the concave indentation  21 B, the satisfactory pressure on the flat cable C is maintained. The cam portion  33  is stable in the concave indentation  21 B so that the movable member  30  will not come off by an accidental force. The movement to the left is restricted by the stopper section  22 C.     (7) Various modifications may be made to the invention. For example, as shown in  FIG. 4 , the concave indentation  22 D is connected to the straight section without making any shoulder as in  FIG. 1 . The cam portion  33  is prevented from coming off to the right by the concave indentation  22 D. The bottom edge  10 C of the housing is press fitted into the attaching recess  22 F of the connection section  22 E to assure the attachment of the terminal to the housing. Also, this facilitates soldering the connection section  22 E at the predetermined position. When the terminal  20  is press fitted into the housing  10 , the lever arm  21  is guided by the tapered section  10 D of the upper wall  10 A.