Patent Publication Number: US-6220881-B1

Title: Card edge connector

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a card edge connector which is inserted into a connector receiving chamber provided with a wiring substrate having a plurality of rectangular terminal connecting portions disposed in predetermined positions on both front and rear surfaces of the wiring substrate, and into which a plurality of terminals each having an elastic contact segment to be in contact with a terminal contact portion via the opening of a corresponding terminal receiving chamber are inserted. 
     2. Description of the Related Art 
     A card edge connector shown in FIG. 6 has been widely known. The card edge connector  1  of FIG. 6 includes terminals  5  each having elastic contact segment  4  inserted into terminal receiving chambers  3  and  3 ′ on the upper side and the lower side of a rectangular connector housing  2 . The card edge connector  1  is to be inserted into a connector receiving chamber  7  provided with a wiring substrate  6  in the middle. 
     In the middle of the connector housing  2 , a space  8  for separating the terminal receiving chambers  3  and  3 ′ and into which the wiring substrate  6  is inserted is provided. The terminal receiving chambers  3  and  3 ′ are provided with openings  9  and  9 ′ communicating with the space  8 , respectively. 
     Each of the terminals  5  is made of a conductive metal material, and comprises an elastic contact segment  4  and a wire connecting portion  11  to which a wire  10  is connected by caulking. The elastic contact segment  4  is provided with a contact portion  12  protruding from the openings  9  and  9 ′ by a predetermined length. The contact portion  12  is situated in the middle of the bent portion. 
     The connector receiving chamber  7  is formed by caving a device casing  13  so as to accommodate the connector housing  2 . Both front and rear surfaces of the wiring substrate  6  are provided with a plurality of rectangular terminal connecting portions (not shown) sandwiched by the elastic contact segments and in contact with the contact portions one by one. 
     When the card edge connector  1  is inserted into the connector receiving chamber  7 , each of the elastic contact segments  4  is brought into contact with corresponding one of the terminal connecting portions and bent by the front surface or the rear surface of the wiring substrate  6 , so that electric connection can be obtained. 
     In the prior art, due to variations in lengths A, B, C, and D indicated in FIG. 6 (length A is the thickness of the wiring substrate  6 , inclusive of the thickness of the terminal connecting portions; length B is the distance between two facing contact portions  12 ; length C is the distance between the inner walls of the connector receiving chamber  7 ; and length D is the height of the connector housing  2  in the direction corresponding to the length C), the contact load of the respective elastic contact segments against the respective terminal connecting portions cannot be stabilized, which might result in a fault in electric contact. 
     Since the device casing  13 , the connector receiving chamber  7 , and the connector housing  2  are all made of a synthetic resin material, they are liable to be adversely affected by a change in the environment. When they are used at a high temperature, the length C of the connector receiving chamber  7  and the length D of the connector housing  2  are increased, with the elastic contact segments  4  being in contact. As the increased amount becomes larger, the contact load becomes smaller. 
     Meanwhile, the elastic contact segments  4  are limited in terms of width, thickness, and flexibility, due to the limited spaces in the terminal receiving chamber  3  and  3 ′ and the space  8 . Moreover, only limited types of material can be used for the elastic contact segments  4 , in view of conductive efficiency. As a result, it becomes difficult to absorb the contact load by adjusting the lengths, and a fault occurs in electric contact. 
     SUMMARY OF THE INVENTION 
     The principal object of the present invention is to provide a card edge connector which can ensure stable contact between terminal connecting portions of a wiring substrate and elastic contact segments. 
     In accordance with a first aspect of the present invention, the card edge connector comprises a first connector housing, a second connector housing, a plurality of terminals, an assisting unit, and a holding mechanism. The first connector housing is to be received by either the front surface or the rear surface of a wiring substrate of a connector housing. The first connector housing has a plurality of first terminal chambers and first openings communicating with the plurality of first terminal chambers. The wiring substrate has a plurality of rectangular terminal connecting portions disposed in predetermined positions on the front surface and the rear surface. The first openings face the surface receiving the first connector housing. The second connector housing is to be received by either the front surface or the rear surface of the wiring substrate whichever does not receive the first connector housing. The second connector housing has a plurality of second terminal chambers and second openings communicating with the second terminal chambers. The second openings face the surface receiving the second connector housing. The plurality of terminals are to be inserted into the first terminal chambers and the second terminal chambers. Each of the terminals is provided with a wire connecting portion and an elastic contact segment having a contact portion to be in contact with corresponding one of the terminal connecting portions via corresponding one of the first openings or the second openings. The edge of each elastic contact segment is bent back toward the wire connecting portion. Each of the contact portions is formed in the middle of the bent portion of the corresponding elastic contact segment. The assisting unit assists the elastic contact segments in resisting separation of the first connector housing and the second connector housing inside the connector receiving chamber. The holding mechanism holds the assisting unit, and is provided to the first connector housing and the second connector housing. The holding mechanism comprises rotary support axes and bearings for rotatably supporting the first connector housing and the second connector housing. 
     With this structure, when the card edge connector is inserted into the connector receiving chamber, the wiring substrate is sandwiched by the elastic contact segments pressing its front and rear surfaces. The elastic contact segments are brought into contact with the terminal connecting portions and flexed to press them, thereby obtaining electric connection. Meanwhile, the assisting unit resists separation of the first connector housing and the second connector housing inside the connector receiving chamber, so as to assist the elastic contact segments in securing required contact load. Even if there is a length variation between the inner walls of the connector receiving chamber, or even if the elastic contact segments wear with time, the assisting unit maintain the contact load required between the contact portions and the terminal connecting portions. 
     As the contact load of the elastic contact segments against the terminal connecting portions of the wiring substrate provided to the connector receiving chamber is stabilized, insufficient contact can be prevented, and high reliability can be expected. 
     In accordance with a second aspect of the present invention, the assistant unit is made up of spring members each having two arms and a coil to be engaged with the holding mechanism, and each of the coils is formed by rounding the mid section of a metal wire. 
     With the assisting unit of this structure, when the card edge connector is inserted into the connector receiving chamber, the two arms push in the opposite direction to the separating direction of the first connector housing and the second connector housing by the wiring substrate with the rotary support axes being the center. In such a condition, even if there is a variation in size or length, the assisting unit assists the elastic contact segments to stabilize the contact load. Since the assisting unit does not need to possess a conductive function, a highly durable wire material such as piano wire can be used. Accordingly, the spring members can function as an assisting unit to provide high reliability. The spring members are also advantageous in that they are easy to produce. 
     In accordance with a third aspect of the present invention, the holding mechanism is provided with arm hooks for receiving the two arms and the rotary support axes to be inserted into the coils. 
     With the holding mechanism of this structure, the two arms become contractible with respect to the coils. As the spring members assist the elastic contact segments within the area determined by the arm hooks, the distribution of the contact load can be controlled by adjusting the positions of the arm hooks. Also, since the holding mechanism has a simple structure, it has no adverse influence on the manufacturing the first and second connector housings. 
     In accordance with a fourth aspect of the present invention, the assistant unit is a spring member comprising two coils to be engaged with the holding mechanism, a crossover disposed between the two coils, and two arms facing to each other and extending from the respective two coils. The two coils are formed by rounding two portions of a metal wire. 
     When the card edge connector is inserted into the connector receiving chamber of the above structure, the two arms and the crossover resist the separation of the first connector housing and the second connector housing by the wiring substrate with the rotary support axes being the center. Even if there is a variation in size or length, the assisting unit assists the elastic contact segments so as to constantly stabilize the contact load. Also, since the assisting unit has no need to have conductive properties, a highly durable material having a high allowable stress, such as piano wire, can be used for the assisting unit. Thus, the spring members can sufficiently function as an assisting unit, thereby providing high reliability. The spring members are also advantageous in that they are easy to produce. 
     In accordance with a fifth aspect of the present invention, the holding mechanism is provided with arm hooks for receiving the rotary support axes to be inserted into the respective coils, and a crossover hook for receiving the crossover. 
     With the holding mechanism of this structure, the two arms and the crossover are contractible with respect to the coils. As the spring members assist the elastic contact segments within the area determined by the arm hooks, the distribution of the contact load can be controlled by adjusting the positions of the arm hooks. Also, since the holding mechanism has a simple structure, it has no adverse influence on the manufacturing the first and second connector housings. 
     The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is. an exploded perspective view of one embodiment of a card edge connector of the present invention; 
     FIG. 2 is an outer perspective view of the card edge connector of FIG. 1; 
     FIG. 3 is a perspective view illustrating another example of the connector receiving chamber of FIG. 1; 
     FIG. 4 is an outer perspective view of another embodiment of a card edge connector of the present invention; 
     FIG. 5 is an outer perspective view of the spring member of FIG. 4; and 
     FIG. 6 is a cross-sectional view of a card edge connector of the prior art. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is a description of one embodiment of the present invention, with reference to the accompanying drawings. 
     In FIG. 1, a card edge connector  21  comprises a first connector housing  22  and a second connector housing  22 ′ both made of synthetic resin, a plurality of terminals  23  to be inserted into the first connector housing  22  and the second connector housing  22 ′, and a pair of spring members  24  to be engaged with the first connector housing  22  and the second connector housing  22 ′. For instance, such a card edge connector is inserted into a connector receiving chamber  26  formed on a device casing  25 , so as to obtain electric connection. 
     The first connector housing  22  and the second connector housing  22 ′ are formed by injection molding to have a rectangular shape. In this embodiment, they have the identical shape and face to each other. Six terminal chambers  27  and six terminal chambers  27 ′ are formed inside the first connector housing  22  and the second connector housing  22 ′, respectively. Each of the terminal receiving chambers  27  and  27 ′ is provided with a known terminal stopper (not shown) such as a lance. Six rectangular openings  28  and six rectangular openings  28  ′ communicating with the respective terminal receiving chambers  27  and  27 ′ are formed on the upper walls  22   a  and  22   a ′ of the first connector housing  22  and the second connector housing  22 ′ corresponding to the front and rear surfaces of a wiring substrate  40  of the connector receiving chamber  26 . 
     Cylindrical rotary support axes  29  and  29 ′, and bearings  30  and  30 ′ having notches  30   a  and  30   a ′ for the spring members  24  and  24 ′ are formed on the rear side of the side surfaces  22   b  and side surfaces  22   b ′ of the first connector housing  22  and the second connector housing  22 ′, respectively. A pair of cylindrical arm hooks  31  and another pair of cylindrical arm hooks  31  protruding in the opposite directions are formed on the front side of the side surfaces  22   b  and  22   b ′. 
     Each of the terminals  23  is formed by stamping out a thin conductive metal plate, and includes an elastic contact segment  32  and a wire connecting portion  34  to which an electric wire  33  is connected by caulking. The edge of the elastic contact segment  32  is bent toward the wire connecting portion  34 , and a contact portion  35  to be in contact with a terminal connecting portion  41  of the connecting receiving portion  26  is formed in the meddle of the bent portion via the corresponding opening  28  or  28 ′. 
     The pair of spring members  24  are metal wires, and coil portions  36  are formed in the middle of the respective spring members  24 . The coil portions  36  have a larger diameter than that of the rotary support axes  29  and  29 ′. Each of the coil portion  36  is provided with a first arm  37  and a second arm  38  both extending straight. The first arm  37  and the second arm  38  face to each other with the coil portion  36  being the center. 
     Meanwhile, the connector receiving chamber  26  has a rectangular box-like housing  39  protruding from the device casing  25 , and the wiring substrate  40  is disposed in the middle of the housing  39 . Since the wiring substrate  40  has a conventional structure, it is not described herein in detail. A plurality of rectangular terminal connecting portions  41  communicating with the respective elastic contact segments  32  are formed on the front and rear surfaces of the wiring substrate  40 . 
     The structure of the wiring substrate  40  is not limited to that of this embodiment, and it is possible to employ a flexible print circuit  43  having terminal connecting portions  42  fixed onto the front and rear surfaces of a substrate  44 . 
     In the following, the process of attaching and inserting the card edge connector  21  into the connector receiving chamber  26  will be described with reference to FIGS. 1 and 2. 
     As shown in FIG. 1, the terminals  34  are inserted into the respective terminal receiving chambers  27  and  27 ′ of the first connector housing  22  and the second connector housing  22 ′. Each of the inserted terminals  23  is then held by the terminal stopper (not shown) and the contact portion  35  of the elastic contact segment  32  of each of the terminals  23  protrudes from the corresponding opening  28  or  28 ′. 
     As shown in FIG. 2, the pair of spring members  24  are then engaged with the side surfaces  22   b  and  22   b ′ of the first connector housing  22  and the second connector housing  22 ′, and the rotary support axes  29  and  29 ′ are engaged with the respective bearings  30  and  30 ′. More specifically, after the coil portions  36  are inserted into the respective rotary support axes  29  and  29 ′, the rotary support axes  29  and  29 ′ are engaged with the respective bearings  30  and  30 ′, and the first arms  37  are hooked by the outer side of the arm hooks  31 . The second arms  38  are pulled and hooked by the outer side of the arm hooks  31  ′. Thus, the attachment of the card edge connector  21  is completed, as shown in FIG.  2 . 
     As the card edge connector  21  is inserted into the connector receiving chamber  26  in the direction of arrow P of FIG. 1, the elastic contact segments  32  sandwich the wiring substrate  40  by the front and rear surfaces. Once the card edge connector  21  is brought into contact with the wiring substrate  40 , the wiring substrate  40  starts separating the first connector housing  22  and the second connector housing  22 ′, with the respective rotary support axes  29  and  29 ′ being the center. Here, the spring members  24  resist the separation, and the contact portion of each of the elastic contact segments  32  is in contact with the corresponding terminal connecting portion  41  and elastically pushes it so as to obtain electric connection. 
     Even if there is a variation in the distance between the upper inner wall and the lower inner wall of the connector receiving chamber  26 , in the height of the card edge connector  21 , or in the total height of the first connector housing  22  and the second connector housing  22 ′ engaged with each other, or even if the elastic contact segments  32  wear with time, the spring members  24  maintain the contact load between each contact portion  35  and the corresponding terminal connecting portion  41 . 
     Accordingly, the card edge connector  21  can always have a stable contact load, so that faults in contact can be prevented, and high reliability can be obtained. 
     Referring now to FIGS. 4 and 5, the following is a description of another embodiment of the present invention. It should be noted here that like components are indicated by like reference numerals in this embodiment and the foregoing embodiment. 
     A card edge connector  45  shown in FIG. 4 differs from the card edge connector  21  in the second connector housing  22 ′ and the spring members  24 . 
     Although the second connector housing  22 ′ is provided with the arm hooks  31 ′ in the foregoing embodiment, a second connector housing  46  of this embodiment is provided with a groove-like crossover hook  47 , instead of the arm hooks  31 ′, on the front wall  46 a of the second connector housing  46 . 
     The front wall  46   a  is formed with a step, and it is preferable for a crossover  50  to provide claws  46   b  to the front wall  46   a , as shown in FIG.  4 . The other structural features are the same as those of the second connector housing  22 ′. 
     Meanwhile, a spring member  48 , equivalent to the spring members  24 , is a metal wire, and coils  49  having a larger diameter than the rotary support axes  29  and  29 ′ are disposed in such positions that they face to each other, as shown in FIG.  5 . The crossover  50  to be hooked by the crossover hook  47  extends from the coils  49 , and arms  51  also extend straight from the coils  49 . 
     The card edge connector  45  of this structure can achieve the same effects as the card edge connector  21 . The process of attaching and inserting the card edge connector  45  into the connector receiving chamber  26  is the same as with the card edge connector  21 . 
     Since any suitable assisting component provided to resist separation of a first connector housing and a second connector housing can bring the above effects when a card edge connector is inserted into a connector receiving chamber, the structure of a card edge connector of this embodiment is not limited to the card edge connectors  21  and  45 . If the assist component is formed from a metal wire spring member, a required contact load for the elastic contact segments can be determined from the spring constant. Also, since such an assist component needs to have no conductive properties, a highly durable material which has a high stress intensity and is hard to wear, such as piano wire, can be employed. 
     Although the present invention has been fully described by way of examples with reference to the accompanying drawings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention, they should be construed as being included therein.