Abstract:
An FPC connector having an electromagnetic wave shielding structure improved so that noises do not exceed an allowable value. The FPC connector includes at least a top plate, a metallic shell having left and right walls and a grounding terminal portion, a connector body covered with the metallic shell, a signal line contact, and a grounding contact for grounding the FPC, wherein the metallic shell has a grounding contact partially cut from the top plate and raised the cut portion.

Description:
[0001]     This application claims priority from Japanese Patent Application Nos. 2003-346284 filed Oct. 3, 2003 and 2004-239954 filed Aug. 19, 2004, which are incorporated hereinto by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a connector for a flexible printed circuit board for mutually connecting electronic components in electronic apparatuses (hereinafter referred to as an FPC connector), more specifically, to the FPC connector improved for forming a ground contact in the FPC connector for avoiding the interfere of electromagnetic waves with the flexible printed circuit (hereinafter referred to as an FPC).  
         [0004]     2. Description of the Related Art  
         [0005]     Up to now, in the FPC connector, part or all of the connector is covered with a metallic shell and the metallic shell and FPC are grounded for shielding the FPC connector from the electromagnetic field as well as suppressing the generation of noise in a signal line or grounding the generated noise as much as possible (see Japanese Patent No. 3425696).  
         [0006]     A typical conventional shield structure is illustrated in  FIG. 7  which is an enlarged sectional view of a portion thereof for grounding the FPC when the FPC is inserted into a FPC connector.  
         [0007]     The FPC connector  101  generally includes a metallic shell  102 , a connector body  103 , a pair of grounding contacts  104  and a plurality of signal line contacts  105 .  
         [0008]     The metallic shell  102  functions as a shield for electromagnetic waves and covers at least upper and left/right sides of the connector body  103  so that it is suitably grounded via the left/right sides to an electronic apparatus to which the FPC connector  101  is attached. The connector body  103  is made of insulating resin and formed as a rectangular tube having an outer shape of substantially a parallelepiped, through which a space  103   a  extends forward/rearward. The grounding contacts  104  is press-fit and fixed into grooves  103   d  formed in a bottom wall  103   c  constituting the space  103   a  of the connector body  103  in correspondence to a grounding pads (not shown) in FPC  110  inserted therein. As shown in  FIG. 7 , the grounding contact  104  is of a generally U-shape and has a contact portion  104   a  to be in contact with the grounding pad of the FPC  110 , a grounding portion  104   b  at the other end, and a fixing portion  104   c  to be press-fit into the groove  103   d  in a middle region thereof. The grounding portion  104   b  is grounded the electronic apparatus to which the FPC connector is attached. The signal line contact  105  includes a contact portion to be in contact with the pad of the FPC  110 , a fixing portion to be fixed to the connector body  103  and a terminal portion  105   a  to be connected to a circuit of the electronic apparatus (see Japanese Patent No. 3425696 or others).  
         [0009]     As shown in  FIG. 7 , when the FPC  110  is guided along an inside surface of an upper wall  103   b  of the FPC connector  101  and inserted into the space  103   a , the grounding contact  104  and the signal line contact  105  fixed to the bottom wall  103   c  are brought into contact with the corresponding pad of the FPC  110  from the lower side; i.e., from the bottom wall side.  
         [0010]     The conventional FPC connector reduces the interference from electromagnetic waves by the above-mentioned electromagnetic wave shielding structure. However, in the conventional FPC connector, since the grounding contact  104  of the FPC is fixed to the bottom wall  103   c  of the connector body  103  and brought into contact with the FPC  110  from underside, the manufacturing error of the depth of the groove  103   d  and the grounding contact  104  itself is generated. Therefore, it is impossible to always maintain a gap between the contact portion  104   a  of the grounding contact  104  and the inside surface of the upper wall  103   b  of the connector body  103  at a constant value. This may result in the adverse contact between the grounding contact  104  and the FPC, which impedes the stable contact. As a result, there is a risk of increasing noises, far from reducing them.  
         [0011]      FIG. 8  is a graph of the measurement of the radiated disturbance of the conventional FPC connector (the electromagnetic disturbance wherein the energy thereof is propagated through a space as electromagnetic waves). As shown in  FIG. 8 , it is apparent that noises having the field strength exceeding the allowable value (the limit line shown by a solid line in the graph) generate in the signal line even in the above-mentioned electromagnetic wave shielding structure.  
         [0012]     The present invention has been made in view of such a problem, and an object thereof is to provide an FPC connector having an electromagnetic wave shielding structure improved so that noises are prevented from exceeding the allowable value.  
       SUMMARY OF THE INVENTION  
       [0013]     To achieve the above-mentioned object, the FPC connector in accordance with the present invention comprises at least a top plate, a metallic shell having left and right walls and a grounding terminal portion, a connector body covered with the metallic shell, a signal line contact, and a grounding contact for grounding the flexible circuit board, wherein the metallic shell has a grounding contact partially cut from the top plate and raised the cut portion.  
         [0014]     The metallic shell preferably further comprises a fixing piece to be press-fit in the connector body, formed by partially cutting from the top plate and bending the cut portion in parallel to the side wall of the metallic shell.  
         [0015]     The metallic shell preferably further comprises an FPC-fixing/removing spring piece formed by partially cutting from the top plate and raising the cut portion, and the FPC-fixing/removing member is held by the spring piece.  
         [0016]     According to the FPC connector of the present invention, it is possible to reduce the manufacturing error in comparison with the prior art wherein the grounding contact is formed as a separate member and attached to the connector body, whereby the electric contact of the FPC with the grounding contacts is further ensured. As a result, it is possible to prevent noises from exceeding the allowable value. Also, since the grounding contact is formed integral with the metallic shell, it is possible to decrease the number of parts and simplify the production process, whereby the production cost is saved.  
         [0017]     By press-fitting the metallic shell into the contact body from the rear side thereof with the fixing piece, it is possible to easily position the grounding contact.  
         [0018]     Further, by partially cutting the spring piece for the FPC-fixing/removing mechanism from the metallic shell and raising the cut portion, it is possible to reduce the production steps and thereby to save the production cost.  
         [0019]     Also, by providing the FPC-fixing/removing mechanism, the inserted FPC does not fall off from the FPC connector.  
         [0020]     The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1A  is an upper plan view of the FPC connector in accordance with the present invention;  
         [0022]      FIG. 1B  is a perspective view of the FPC connector in accordance with the present invention;  
         [0023]      FIG. 2  is a perspective view of a metallic shell of the FPC connector;  
         [0024]      FIG. 3A  is a sectional view of the FPC connector taken along a line A-A when the FPC is not inserted;  
         [0025]      FIG. 3B  is a sectional view of the FPC connector taken along a line B-B when the FPC is not inserted;  
         [0026]      FIG. 4A  is a sectional view of the FPC connector corresponding to  FIG. 3A  when the FPC is inserted;  
         [0027]      FIG. 4B  is a sectional view of the FPC connector corresponding to  FIG. 3B  when the FPC is inserted;  
         [0028]      FIG. 5  is a schematic plan view of a stopper member  7  constituting an FPC-fixing/removing mechanism;  
         [0029]      FIG. 6A  is a sectional view taken along a line C-C in  FIG. 1A  when the FPC is not inserted;  
         [0030]      FIG. 6B  is a sectional view taken along a line C-C in  FIG. 1A  when the FPC is inserted;  
         [0031]      FIG. 6C  is a sectional view taken along a line C-C in  FIG. 1A  illustrating a state of the FPC-fixing/removing mechanism after the FPC has been inserted;  
         [0032]      FIG. 7  is an sectional view of a portion for grounding FPC when the FPC is inserted into the conventional FPC connector; and  
         [0033]      FIG. 8  is a graph illustrating the field strength of noises generated in the conventional FPC connector by the radiated disturbance.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0034]     The preferred embodiments of the present invention will be described below with reference to  FIGS. 1A  to  4 B.  
         [0035]      FIGS. 1A and 1B  illustrate the FPC connector in accordance with the present invention, wherein  FIG. 1A  is an upper view thereof;  FIG. 1B  is a perspective view thereof;  FIG. 2  is a perspective view of a metallic shell of the FPC connector;  FIGS. 3A and 3B  are sectional views of the FPC connector when the FPC is not inserted, more specifically  FIG. 3A  is a sectional view taken along a line A-A in  FIG. 1A  and  FIG. 3B  is a sectional view taken along a line B-B in  FIG. 1A ; and  FIGS. 4A and 4B  are sectional views of the FPC connector similar to  FIGS. 3A and 3B  when the FPC is inserted, more specifically  FIG. 4A  is a sectional view taken along a line A-A in  FIG. 1A  and  FIG. 3B  is a sectional view taken along a line B-B in  FIG. 1A .  
         [0036]     As shown in  FIGS. 1A and 1B , the FPC connector in accordance with the present invention generally includes a metallic shell  2 , a connector body  3  and a plurality of signal line contacts  5 .  
         [0037]     The metallic shell  2  functions for shielding electromagnetic waves in a similar manner as in the prior art. The metallic shell  2  includes a top plate  21  for covering at least an upper portion of the connector body  3 , and side walls  22   a ,  22   b  for covering left and right portions of the connector body  3 . The metallic shell  2  is suitably grounded via grounding terminal portions  23   a ,  23   b  provided at lower ends of the left and right side walls  22   a ,  22   b , respectively, to an electronic apparatus to which the FPC connector  1  is attached.  
         [0038]     According to the present invention, as clearly shown in  FIG. 2 , a pair of grounding contacts  24   a ,  24   b  is formed integral with the metallic shell  2  in correspondence to grounding pads of the FPC  10 . Each of the grounding contacts  24   a ,  24   b  is formed, for example, by partially press-cutting from the top plate  21  of the metallic shell  2  and raising the cut portion to be a piece having a predetermined shape extending downward from the top plate in the vertical direction, which piece is then bent to have a generally L-shape with a C-shaped free end. In this production process, the pair of grounding contacts  24   a ,  24   b  having the FPC contact portions  24   a   1 ,  24   b   1 , which are elastically deformable free ends, are formed at the same time.  
         [0039]     By forming the pair of grounding contacts  24   a ,  24   b  in such a manner and sandwiching the FPC  10  between the top plate  21  of the metallic shell  2  and the grounding contacts  24   a ,  24   b  along an upper wall  32  of the connector body  3  (see  FIG. 4B ), it is possible to reduce the manufacturing error in comparison with the prior art wherein the grounding contact is formed as a separate member and attached to the connector body  3 , whereby the electric contact of the FPC with the grounding contacts  24   a ,  24   b  is further ensured. Also, since the grounding contacts  24   a ,  24   b  are formed integral with the metallic shell  2 , it is possible to decrease the number of parts and simplify the manufacturing process as well as save the production cost.  
         [0040]     In this regard, in  FIG. 2 , reference numerals  25   a ,  25   b  denote a pair of spring pieces for facilitating the attachment/detachment of the FPC  10  relative to the connector  1  described later, which constitutes a FPC-fixing/removing mechanism. The pair of spring pieces  25   a ,  25   b  is disposed outside the pair of grounding contacts  24   a ,  24   b , and is partially cut from the top plate  21  of the metallic shell  2  and raised the cut portion in a similar manner as the pair of grounding contacts  24   a ,  24   b . Also, reference numerals  26   a ,  26   b  denote a pair of fixing pieces for fixing the metallic shell  2  to the connector body  3 , which is partially cut from the top plate  21  and bent the cut portion in parallel to the side walls  22   a ,  22   b , respectively, in a rear area (an upper area in FIG.  1 A) of the metallic shell  2 . The pair of spring pieces  25   a ,  25   b  and the pair of fixing pieces  26   a ,  26   b  may be formed at the same time in the process for forming the grounding contacts  24   a ,  24   b.    
         [0041]     The contact body  3  is made of insulating resin to have an outer shape of a generally parallelepiped and formed as a rectangular tube, through which a space  31  extends forward/rearward of the connector body  3  (the upward/downward direction in  FIG. 1A ). In the space  31 , the FPC  10  can be inserted. The connector body  3  is provided with a stopper member  7  constituting a fixing/removing mechanism for facilitating the attachment/detachment of the FPC in front of the upper wall  32  defining the upper limit of the space  31  (in a lower area in  FIG. 1A ), and a positioning projection  6  for attaching the connector body to the electronic apparatus at a predetermined position in a lower area of a lower wall  33  defining a lower limit of the space  31  (see  FIGS. 3A and 3B ).  
         [0042]     The fixing piece  26  of the metallic shell  2  and bases  52  of the signal line contacts  5  described later are press-fit into holes formed respectively in the connector body  3  in correspondence thereto from a rear side of the connector body  3  (from the upper side in  FIG. 1A  and the right side in  FIGS. 3A  to  4 B), whereby the metallic shell  2  and the signal line contacts  5  are fixed to the connector body  3 . Simultaneously therewith, the pair of grounding contacts  24 ,  24  and the signal line contacts  5  are correctly located in the interior of the space  31  of the contact body  3 .  
         [0043]     As shown in  FIGS. 3A and 4A , the signal line contact  5  includes a movable contact portion  51  brought into contact with a signal line pad of the FPC corresponding thereto, a base  52  press-fit into a hole or a slit  34  formed in the connector body  3 , a terminal portion  54  as a soldering portion being electrically connected to an electrode pad of the circuit board in the electronic apparatus, and a coupling portion  53  for coupling the movable contact portion  51  and the base  52  with the terminal portion  54 . As clearly shown in  FIG. 4A , the signal line contact  5  is formed to sandwich the FPC  10  between the base  52  and the movable contact portion  51  via the upper wall  32  of the connector body  3 .  
         [0044]     Next, the FPC-fixing/removing mechanism for facilitating the attachment/detachment of the FPC will be described with reference to  FIG. 5 .  FIG. 5  is a schematic plan view of the stopper member  7  constituting the FPC-fixing/removing mechanism wherein the FPC  10  is inserted.  
         [0045]     The stopper member  7  includes a push button  71  located in a generally middle portion thereof, a pair of arm members  72   a ,  72   b  extending leftward and rightward from the push button  71 , a pair of projections  73   a ,  73   b  extending rearward from front ends which are free ends of the arm members  72   a ,  72   b  generally in the vertical direction thereto, and a pair of engagement members  74   a ,  74   b  extending inward (to a center) from front ends of the projections  73   a ,  73   b  generally in the vertical direction thereto. The front ends of the pair of arm members  72   a ,  72   b  are elastically held by the pair of spring pieces  25   a ,  25   b  partially cut from the top plate  21  of the metallic shell  2  and raised the cut portion to be located on the lower side (the back side of the paper in  FIG. 5 ) (see  FIG. 6A ). Also, the pair of engagement members  74   a ,  74   b  is projected inward from the projections  73   a ,  73   b  to be located on a passage of the FPC  10  inserted into the space  31 . Accordingly, they are engageable with a pair of recesses  12   a ,  12   b  formed on both sides of the front end of the FPC  10  inserted.  
         [0046]     The operation of the FPC-fixing/removing mechanism of the above-mentioned structure will be described with reference to  FIGS. 6A  to  6 C.  FIGS. 6A  to  6 C are the C-C cross-section in  FIG. 1A  and illustrate the operation of the spring piece and the stopper member constituting the FPC-fixing/removing mechanism.  
         [0047]     As shown in  FIG. 6A , when the FPC  10  is absent, the stopper member  7 , more accurately the arm members  72   a ,  72   b  are pushed upward by the corresponding spring pieces  25   a ,  25   b.    
         [0048]     In  FIG. 6B , when the FPC  10  is inserted into the FPC connector  1 , the push button  71  of the stopper member  7  is pushed down by a finger or others. Then, the arm members  72   a ,  72   b  formed in integral with the push button  71  are also pushed down against the elastic force of the spring pieces  25   a ,  25   b . Thereby, the projections  73   a ,  73   b  and the engagement members  74   a ,  74   b  formed in integral with the arm members  72   a ,  72   b  are also pushed down.  
         [0049]     When the engagement members  74   a ,  74   b  are pushed down to get out of the passage of the FPC  10 , the FPC  10  can be inserted to a predetermined position in the space  31 . When the pressure applied to the push button  71  is released after the FPC  10  has completely been inserted, the stopper member  7  including the arm members  72   a ,  72   b  returns to the original position (see  FIG. 6C ). Accordingly, the engagement members  74   a ,  74   b  also return to the passage of the FPC  10  in the space  31 .  
         [0050]     At this time, if the FPC  10  is inserted to the predetermined position, the engagement members  74   a ,  74   b  are fit into the recesses  12   a ,  12   b . Thereby, the FPC  10  is electrically brought into contact with the signal line contacts  5  and the grounding contacts  24   a ,  24   b , and assuredly fit to the FPC connector  1  without falling off therefrom.  
         [0051]     When the FPC  10  is detached from the FPC connector  1 , the push button  71  of the stopper member  7  is pushed down in a similar manner as shown in  FIG. 6B  to detach the engagement members  74   a ,  74   b  from the corresponding recesses  12   a ,  12   b  of the FPC  10 . Thereby, the FPC  10  is removable from the connector  1 .  
         [0052]     Since the FPC connector  1  in accordance with the present invention is structured as described above, if the FPC is inserted into the space  31  from the front side of the connector body  3 , the respective pads of the FPC  10  are electrically connected to the respective signal line contacts  5  corresponding thereto while being sandwiched between the upper wall  32  of the connector body  3  and the signal line contacts  5  or the grounding contacts  24  as shown in  FIGS. 4A and 4B , and the FPC  10  is assuredly held in the connector  1  by the action of the FPC-fixing/removing mechanism, whereby the FPC  10  does not fall off from the connector  1  during the use. In this regard, reference numeral  11  shown in  FIGS. 4A and 4B  denotes a spacer of insulating resin attached to the back side of the FPC (opposite to a side on which the pads are formed), which is not indispensable but preferably provided for ensuring the attachment/detachment of the FPC relative to the connector or increasing the contact pressure of the pads in the FPC and the respective contacts.  
         [0053]     The present invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspect, and it is the intention, therefore, in the apparent claims to cover all such changes and modifications as fall within the true spirit of the invention.