Patent Publication Number: US-6338648-B1

Title: Electrical connector for flexible printed board

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119 of Japanese Patent Application No.11-124566 filed on Apr. 30, 1999, the abstract of disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electrical connector for flexible printed board called FPC (Flexible Printed Circuit). 
     2. Description of Related Art 
     There has been known to the art the connector of this type which includes a synthetic-resin housing having an opening and contacts facing the opening, and a synthetic-resin cover which is pivotally movable to open/close the opening of the housing and which, at closed position, maintains the FPC pressed against the contacts. 
     The cover is integrally formed with a pair of resin projections, as support shafts, at opposite ends of one edge thereof. As born on pivotal support portions of the housing (or members retained by the housing), these support shafts permit the cover to pivot between an opened position and the closed position. 
     On the other hand, the cover is integrally formed with a pair of resin locking projections at opposite ends of the other edge thereof. The locking projections are brought into engagement with lock notches of the housing for establishing lock (see, for example, Japanese Utility Model Laid-Open Gazette No. 6-77186). 
     The aforesaid resin locking projections are relatively small in diameter and susceptible to deformation or breakage. In particular, repeated openings and closings of the cover involve disadvantages that the lock comes loose due to the deformed locking projection or fails due to the broken locking projection. 
     More recently, there has been a growing trend to reduce pitch between contacts or to increase multipolar contacts. This leads to the adoption of synthetic resin materials for the cover which have enough fluidity to ensure dimensional accuracy. Unfortunately, the synthetic resin materials of this type tend to decrease in toughness, resulting in higher incidence of locking projection breakage. 
     SUMMARY OF THE INVENTION 
     The invention seeks to provide an electrical connector for flexible printed board which features positive locking of the cover and a locking mechanism rigid enough to withstand repeated openings and closings of the cover. 
     In accordance with a preferred embodiment of the invention, this object is accomplished in an electrical connector for flexible printed board which comprises a synthetic-resin housing including an opening and contacts facing the opening; a synthetic-resin cover which is rotatable around a predetermined axis between an opened position and a closed position to press a flexible printed board against the contacts; a locking mechanism for locking the cover in the closed position; first metallic reinforcement means which is partially embedded in the cover during the molding of the cover; and second metallic reinforcement means fixed to the housing, the connector characterized in that the locking mechanism is respectively disposed in the first and the second reinforcement means and includes a first and a second engagement portions which releasably engage with each other. 
     According to the embodiment of the invention, the locking of the cover is ensured because the cover is locked by means of the engagement between the rigid metallic members. Further, the locking mechanism withstands the repeated openings and closings of the cover. In addition, the first reinforcement means has high adhesion to the cover because the first reinforcement means is inserted in the cover during the molding thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view showing a FPC connector according to one embodiment of the invention and an FPC; 
     FIG. 2 is a partially cutaway plan view showing the connector with a cover opened; 
     FIG. 3A is a sectional view taken on the line III—III in FIG. 2 whereas FIG. 3B shows the cover of FIG. 3A in closed position, FIGS. 3A and 3B omitting the hatching of an area representing the section of a reinforcement tab; 
     FIG. 4 is a sectional view taken on the line IV—IV in FIG.  2  and omits the hatching of an area representing the section of a first contact; 
     FIG. 5 is a sectional view taken on the line V—V in FIG.  2  and omits the hatching of an area representing the section of a second contact; 
     FIG. 6 is a perspective view showing the connector with the cover almost closed; 
     FIG. 7 is a partially cutaway plan view showing the cover; 
     FIG. 8 is a sectional view taken on the line VIII—VIII in FIG. 7; 
     FIG. 9 is a sectional view showing the connector with the FPC connected and corresponding to FIG. 5; 
     FIG. 10 is a schematic diagram showing a combination of a wire member and reinforcement tabs according to another embodiment of the invention; 
     FIGS. 11A and 11B are a schematic front view and a schematic bottom view showing a cover according to yet another embodiment of the invention; 
     FIG. 12 is a schematic sectional view showing a connector according to still another embodiment of the invention; and 
     FIG. 13 is a schematic sectional view showing a connector according to yet another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, preferred embodiments of the invention will be described with reference to the accompanying drawings. 
     Referring to FIGS. 1 and 2, an electrical connector for flexible printed board  1  (hereinafter, simply referred to as “connector  1 ”) according to one embodiment of the invention includes a synthetic-resin housing  4  defining an insertion space  3  where a flexible printed board  2  (hereinafter, simply referred to as “FPC  2 ”) is inserted from front or removed. A front half portion of the housing  4  upwardly opens via an opening  6  of a top plate  5  of the housing  4  and is provided with a cover  7 , a molded article of synthetic resin, which is pivotally movable to open or close the opening  6 . 
     Indicated at  51  is a metallic wire as a first reinforcement member embedded in the cover  7 . Opposite ends of the wire  51  include a pair of locking projections C, as a first engagement portion. As shown in FIGS. 3B and 6, each locking projection C locks in a lock notch  50 , as a second engagement portion, of a corresponding reinforcement tab  10  formed of a metal sheet, as a second reinforcement member fixed to the housing  4 , thereby locking the cover  7  in closed position. The locking projections C of the wire  51  and the lock notches  50  constitute a locking mechanism. 
     Indicated at  45  is a metallic wire, as a third reinforcement member, embedded in the cover  7 . Opposite ends of the wire  45  include a pair of pivot shafts A. Openings  53 ,  54  are defined in the cover  7  for exposing respective parts of the corresponding wires  45 ,  51  as exposure portions  58 ,  59  to the outside of the cover  7 . 
     Opposite side plates  8 ,  9  of the housing  4  define lateral sides of the insertion space  3 . A pair of fixing holes  11  open to respective front end faces of the side plates  8 ,  9  (not shown in FIG. 1 but illustrated in FIG.  2  and FIG. 3A which is a sectional view taken on the line III—III in FIG.  2 ). The fixing holes  11  respectively receive from front and fix the reinforcement tabs  10  which support the pair of pivot shafts A projecting laterally of the cover  7 , respectively. 
     Referring to FIGS. 3A and 3B, the reinforcement tab  10  includes a main body  12 , a pivotal support portion  14  for supporting the pivot shaft A and a hook-shaped fixing portion  15  soldered to a substrate surface. The main body  12  is inserted into the fixing hole  11  from front so as to be fixed via a locking projection. The pivotal support portion  14  is comprised of a U-shaped notch defined by an extension piece  13  extending upward from a front end of the main body  12 . The pivotal support portion  14  pivotally supports the corresponding pivot shaft A. The fixing portion  15  extends downward from the front end of the main body  12 . 
     An extension piece  57  also extends upward from upper front end of the main body  12 . The aforesaid lock notch  50  is formed in a fore-end face of the extension piece  57 , serving to lock the cover  7  in the closed position through engagement with the locking projection C. An abutting portion  60  of the housing  4  is abutted against the pivot shaft A received by the U-shaped notch as the pivotal support portion  14 , thereby retaining the pivot shaft A in the U-shaped notch. 
     Turning back to FIGS. 1 and 2, the side plates  8 ,  9  are formed with extensions  17 ,  18  extended forward, respectively. The extensions  17 ,  18  have a smaller thickness than the side plates  8 ,  9 . The extensions  17 ,  18  are located laterally outside of the neighboring fixing holes  11 , extending to some point of the lateral sides of the opening  6 . Guide walls  19 ,  20  upstand from opposite side edges of a front portion of a bottom plate  16  of the housing  4 . When the cover  7  is closed, the guide walls  19 ,  20  are received by corresponding U-shaped gaps  21  defined at lateral edges of the cover  7 , thereby restricting the lateral movement of the cover  7 . 
     Within the insertion space  3  of the housing  4 , a plurality of first and second fork-shaped contacts  22 ,  23  are arranged in two rows in a zigzag fashion. 
     Referring to FIGS. 1,  2  and  4  which is a sectional view taken on the line IV—IV in FIG. 2, the first contact  22  is comprised of a metallic member which is inserted, from front, into the insertion space  3  of the housing  4  and fixed. As seen in FIG. 4, the first contact  22  includes a fixing piece  25  inserted, from front, into a receiving groove  24  defined in an upper surface of the bottom plate  16  of the housing  4 , and a resilient piece  26  located above the fixing piece  25  in a rear half portion of the insertion space  3 . 
     A locking piece  27  with a locking projection extends rearwardly from an interconnection between the fixing piece  25  and the resilient piece  26 . The locking piece  27  is inserted into a fixing hole  28  of the housing  4  and fixed. The fixing piece  25  is provided with a lead portion  29  of inverted T-form at its front end. The lead portion  29  is soldered to the substrate surface on which the present connector  4  is mounted, while engaging a front edge of the bottom plate  16  of the housing  4  for preventing the upward dislocation of the fixing piece  25 . Chevron-shaped projections  30 ,  31  are formed at the fixing piece  25  and the resilient piece  26  in opposed relation, for clamping the inserted FPC  2  therebetween thereby to ensure a contact pressure on the FPC  2 . 
     Referring to FIGS. 1,  2  and  5  which is a sectional view taken on the line V—V in FIG. 2, the second contact  23  is comprised of a metallic member which is inserted, from rear, into the insertion space  3  of the housing  4  and fixed. As seen in FIG. 5, the second contact  23  includes a fixing piece  33  with a locking projection, a resilient piece  35  located below the fixing piece  33 , a main body  36  and a lead portion  37 . 
     The fixing piece  33  is inserted, from rear, into a fixing hole  32  at an upper part of the housing  4  and fixed. The resilient piece  35  is inserted, from rear, into a receiving groove  34  defined in the upper surface of the bottom plate  16  of the housing  4 . The main body  36  interconnects rear ends of the fixing piece  33  and the resilient piece  35 . The lead portion  37  extends rearward from the main body  36  in an obliquely downward direction and is soldered to the substrate surface. 
     Respective front ends  38 ,  39  of the fixing piece  33  and the resilient piece  35  reach a midportion of the housing  4  with respect to the anteroposterior direction thereof. The front end  38  of the fixing piece  33  enters an open hole  40  of the cover  7  when the cover  7  of FIG. 5 is closed. Further, the front end  38  exposes itself to the outside thereabove via an open area B defined along an edge of the cover  7  when the cover  7  is closed, as shown in FIGS. 6 and 9. Thus, the continuity test may be readily performed by bringing a continuity test probe into contact with the front end  38  of the fixing piece  33  of the second contact  23  via the open area B of the closed cover  7 . 
     On the other hand, the front end  39  of the resilient piece  35  is formed with an upward chevron-shaped projection  41  for ensuring the contact pressure on the FPC  2 . 
     Referring to FIGS. 1 and 7 which is a plan view of the cover, the cover  7  is of a rectangular plate, having first and second edges  42 ,  43  in opposed relation. The aforesaid pair of pivot shafts A project from opposite lateral ends  44 ,  44  of the first edge  42 , respectively. 
     The pivot shaft pair A comprise exposed opposite ends  46 ,  46  of the metallic wire  45  which is embedded in the cover  7  during the molding thereof. The whole body of the wire  45  takes on a crank form, an intermediate portion  47  of which extends parallel to the first edge  42  as spaced a distance therefrom. 
     Along the first edge  42  of the cover  7 , a plurality of open holes  40  are arranged in side-by-side relation for permitting the retractable entrance of the front ends  38  of the second contacts  23 , as shown in FIG.  5 . In FIG. 7, a portion closer to the first edge  42  than the open holes  40  defines a pressing portion  48 . 
     When the cover  7  is moved to the closed position, the pressing portion  48  presses the FPC  2  against the resilient piece  35  as clamped between the FPC  2  on the resilient piece  35  of the second contact  23  and the fixing piece  33 , as shown in FIG.  9 . 
     Turning back to FIG. 7, the pair of locking projections C project from opposite lateral ends  49 ,  49  of the second edge  43  of the cover  7 , respectively, so as to engage the corresponding lock notches  50  of the reinforcement tabs  10 . When the cover  7  is closed, the locking projections C engage the lock notches  50  thereby to lock the cover  7  in the closed position. An arrangement is made such that when the cover  7  is closed, the pair of reinforcement tabs  10 , indicated by the two-dot chain line in FIG. 7, couple the respective ends (equivalent to the pivot shafts A) of the wire member  45  with the corresponding ends (equivalent to the locking projections C) of the wire  51  as a lock shaft, for forming a rectangular closed loop of the wire  45 , wire  51  and reinforcement tab pair  10 ,  10 . 
     The locking projection pair C comprise exposed opposite ends  52 ,  52  of the metallic wire  51  which is embedded in the cover  7  during the molding thereof. The whole body of the wire  51  take on a crank form, an intermediate portion  52  of which extends parallel to the second edge  43  as spaced a distance therefrom. 
     Referring to FIGS. 7 and 8 which is a sectional view taken on the line VIII—VIII in FIG. 7, there are provided one or more openings  53  for exposing the wire  45  whereas one or more openings  54  are provided for exposing the intermediate portion of the wire  51 . These openings  53 ,  54  play the following role. In order to insert the metallic wires  45 ,  51  in an article being molded for producing the cover  7  with the wires embedded therein, the metallic wires  45 ,  51  must be supported in a given position within the molding die. The openings  53 ,  54  permit wide support pins (insert pins) to be placed in the molding die at places in correspondence thereto. Thus, the wires  53 ,  54  may be stably supported within the molding die. As a result, the molded article has high positional accuracies for the pivot shafts A and locking projections C which are comprised of the opposite ends of the wires  45 ,  51 , respectively. 
     The present embodiment is designed to lock the cover  7  by bringing the locking projections C, being the ends of the metallic wire  51 , into engagement with the lock notches  50  of the metallic reinforcement tabs  10 . Therefore, the cover is positively locked. It is also ensured that the locking mechanism withstands the repeated openings and closings of the cover  7 . Since the wire  51  as the lock shaft is inserted in the cover  7  during the molding thereof, high adhesion is accomplished between the lock shaft and the cover  7 . 
     In addition, since the reinforcement tabs  10  for reinforcing the housing  4  are formed with the lock notches  50 , the structure is simplified as compared with a case where a separate member with the lock notch is added. 
     Furthermore, the cover  7  is improved in the substantial strength because the pivot shafts A are formed of metal and supported by the pivotal support portions  14  of the metallic reinforcement tabs  10 . The mechanism for supporting the cover  7  in the pivotal movement is subject to counterforce of the lock. If the mechanism for supporting the pivotal movement should be embodied in resin members engaged each other, the members may suffer relatively low strength. On this account, the present embodiment employs the metallic members in engaged relation as the mechanism for supporting the pivotal movement so as to achieve the increased strength. 
     Particularly when closed, the resin cover  7  is reinforced by the metallic members  45 ,  10 ,  51 ,  10  forming the rectangular closed loop, as shown in FIG.  7 . This provides the more positive locking of the cover  7 . 
     It is noted that the present invention is not limited to the above embodiment. For instance, in addition to the reinforcement tabs  10 ,  10  adapted to engage the opposite ends of the wire  51  as the lock shaft, a reinforcement tab  58  may be fixed to the housing  4  so as to engage at least one exposure portion  59  of the axially intermediate portion of the wire  51 , as shown in FIG.  10 . This arrangement is effective to prevent the widthwise deflection of the intermediate portion of the cover  7 , which has particularly a great width for accommodating a great number of contacts. Hence, the more positive locking of the cover is accomplished. Incidentally, there may be provided a plurality of reinforcement tabs  58  for the intermediate portion. 
     As shown in FIGS. 11A and 11B, an alternative arrangement may be made wherein the wire  51  as the lock shaft extends in a length such as not to project beyond the lateral sides of the cover  7  and exposes itself to the outside therebelow via a pair of recesses defined in a lower surface of the cover  7 . This arrangement is effective to protect the wire  51  because the wire  51  does not project to the outside and is free from unwanted external force. 
     In the embodiment of FIG. 3A, the lock notch  50  is formed at the extension piece  57  of the reinforcement tab  10  but may not necessarily be formed in this manner. As shown in FIG. 12, the lock notch  50  may be formed in a front end face of the main body  12 . 
     As shown in FIG. 13, the substantially L-shaped extension piece  13  of the reinforcement tab  10  may be replaced by a straight extension piece  13   a  extending substantially orthogonally from the main body  12 . In this case, the extension piece  13   a  serves to prevent the corresponding pivot shaft A from being dislocated from place in a direction to draw out the FPC  2 (leftward as seen in the figure). 
     In the above embodiments, the first engagement portion is embodied in the locking projection C while the second engagement portion is embodied in the lock notch  50 . However, the first and second engagement portions are not limited to this arrangement but any arrangement permitting the both engagement portions to engage in projection-recess relation is usable. For instance, an end of the first reinforcement member may be bent into a semi-circular arch to define a recess as the first engagement portion, which may be engaged with a projection as the second engagement portion of the housing. 
     The locking projection C as the first engagement portion may have the whole periphery thereof exposed, as illustrated in the above embodiments, or otherwise have a half of the periphery thereof exposed with the other half embedded. In a case where the first reinforcement member is of a circular form in section, for example, the reinforcement member may have a portion thereof exposed as a semi-cylindrical projection extended along the surface of the cover, the semi-cylindrical projection adapted to engage the lock notch. 
     The first reinforcement member may be round or square in section. In the case of the square section, the first reinforcement member may have further increased adhesion to the cover. 
     The present invention is also applicable to a slide-type connector for FPC wherein the lock may be established by the engagement between metallic members of the slider and reinforcement member used in combination. Other various changes and modifications are possible within the scope of the invention.