Abstract:
A plug-in circuit board assembly requires reduced insertion force during connection to a plurality of shorting contacts in a socket or receptacle. The connector portion of the circuit board assembly has a pair of end sections with beveled insertion edges that extend substantially perpendicular to the insertion direction of the circuit board. A shallow V-shaped cut-out with non-beveled insertion edges is located between the end sections. Electrically conductive fingers are carried by the connector portion of the circuit board assembly and extend toward the insertion edges of the end sections and V-shaped cut-out. The electrically conductive fingers adjoining the V-shaped cut-out are positioned to make contact with shorting contacts in the socket or receptacle, while the electrically conductive fingers of the beveled end sections are positioned to make contact with conventional (non-shorting) contacts in the socket or receptacle. The angled insertion edges of the V-shaped cut-out cause the electrically conductive fingers adjoining the cut-out to make contact with the shorting contacts in a sequential or progressive manner when the circuit board assembly is inserted into the socket or receptacle, thereby reducing the insertion force that would otherwise be encountered due to the absence of a bevel on the insertion edges of the cut-out

Description:
The present invention claims the benefit under 35 U.S.C. §119(e) of a U.S. provisional application of Paul Bock, Jr. et al. entitled “Plug-in Circuit Card With Reduced Insertion Force Feature”, Ser. No. 60/154,320, filed Sep. 17, 1999, the entire contents of which are expressly incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention The present invention relates to a plug-in circuit board that is receivable in an electrical socket or receptacle. More particularly, the present invention relates to a male connector portion of such a circuit board that can be inserted into female shorting contacts contained in the socket or receptacle. 
     2. Description of the Related Art 
     Shorting contacts are electrical contacts that must, at any given time, either form a short circuit between the contacts or provide electrical contact with the connector portion of a plug-in circuit board that is inserted between the shorting contacts. In other words, it is undesirable to even momentarily open-circuit the shorting contacts while the circuit board is being inserted. Such an open-circuit condition, even if relatively brief, can cause disruptions in the operation of the electrical circuitry to which the shorting contacts are connected. 
     U.S. Pat. No. 5,088,931 to Niciolo et al., the entire contents of which are expressly incorporated herein by reference, addresses this problem by providing a notch in the connector portion of a plug-in circuit board so that the shorting contacts in the corresponding socket are not forced open until electrical contact is made with the circuit board. However, the Niciolo et al. patent does not address the problem of excessive insertion force that results when there are many shorting contacts which must engage the electrical contacts on the circuit board. 
     When inserting a plug-in circuit board into a socket or receptacle, it is desirable to have a low insertion force. Conventionally, the insertion edge of a circuit board is beveled to reduce insertion force when inserting the circuit board into the receptacle. Inserting a beveled card into a receptacle that has shorting contacts is problematic in that the shorting contacts are forced apart by the insulating material of the circuit board prior to connection to the metal contacts on the circuit board. Thus, beveling the insertion edge is not a solution to the problem of reducing insertion force when making contact with a large number of shorting contacts. 
     What is needed is a circuit board that can mate be connected to a large number of shorting contacts during insertion into a socket or receptacle without requiring that excessive insertion force be used. What is also needed is a circuit board that allows for sequential connections to be made between the electrical contacts on the circuit board and the shorting contacts of the socket or receptacle. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to overcome the problems that arise during insertion of a circuit board into a socket or receptacle when numerous shorting contacts are present in the receptacle. 
     It is also an object of the invention to provide a plug-in circuit board that will not disrupt the operation of electrical circuits in the connected equipment when numerous shorting contacts are being connected. 
     It is another object of the invention to provide a plug-in circuit board requiring low insertion force during insertion into a socket or receptacle when the socket or receptacle contains numerous shorting contacts. 
     It is yet another object of the invention to allow sequential electrical connections to be made between a plug-in circuit board and a socket or receptacle when numerous shorting contacts are involved. 
     It is still a further object of the invention to provide a plug-in circuit board that can be safely and easily installed and removed from a socket or receptacle that includes both shorting contacts and conventional contacts. 
     In accordance with one aspect of the present invention, a plug-in circuit board assembly comprises a circuit board made of an electrically insulating material with a plurality of electrical components mounted thereon, and a connector portion extending from one side of the circuit board and adapted to be inserted into a socket or receptacle when the circuit board assembly is moved in an insertion direction. The connector portion has a first insertion edge which extends substantially perpendicular to the insertion direction of the circuit board, and a second insertion edge which extends at an oblique angle with respect to the insertion direction of the circuit board. A first plurality of electrically conductive fingers are carried by the connector portion and extend toward the first insertion edge. A second plurality of electrically conductive fingers are also carried by the connector portion and extend toward the second insertion edge. The second insertion edge may be recessed with respect to the first insertion edge. The first insertion edge is preferably beveled, and the second insertion edge is preferably not beveled. The oblique angle is preferably between about 5 and 10 degrees. Preferably, at least one of the first plurality of conductive fingers does not extend to the first insertion edge, whereas each of the second plurality of electrically conductive fingers preferably extends to the second insertion edge. The connector portion may be integral with the circuit board, and a faceplate may be connected to the side of the circuit board opposite the connector portion. 
     In accordance with a second aspect of the present invention, a plug-in circuit board assembly comprises a circuit board made of an electrically insulating material with a plurality of electrical components mounted thereon, and a connector portion extending from one side of the circuit board and adapted to be inserted into a socket or receptacle when the circuit board assembly is moved in an insertion direction. The connector portion has a pair of end sections with beveled insertion edges that extend substantially perpendicular to the insertion direction of the circuit board, and a cut-out section located between the end sections. The cut-out section has at least one non-beveled insertion edge that extends at an oblique angle with respect to the insertion direction of the circuit board. A first plurality of electrically conductive fingers carried by the connector portion extends toward the beveled insertion edges of the end sections. A second plurality of electrically conductive fingers carried by the connector portion extends toward the non-beveled insertion edge of the cut-out section. Preferably, the oblique angle between the non-beveled insertion edge of the cut-out section and the insertion direction of the circuit board is between about 5 and 10 degrees. It is also preferred that at least some of the first plurality of electrically conductive fingers do not extend to the beveled insertion edges of the end sections, and that each of the second plurality of conductive fingers extends to the non-beveled edge of the cut-out section. The connector portion is preferably integral with the circuit board. The cut-out section may have a pair of non-beveled insertion edges which extend at opposite oblique angles with respect to the insertion direction of the circuit board, thereby forming a generally V-shaped recess in the connector portion. A faceplate may be connected to the side of the circuit board opposite the connector portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, advantages and novel features of the present invention will be more readily appreciated from the following detailed description when read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a left side view of a plug-in circuit board assembly according to a first embodiment of the present invention; 
     FIG. 2 is a right side view of the plug-in circuit board assembly of FIG. 1; 
     FIG. 3 is a front view of the plug-in circuit board assembly of FIGS. 1 and 2; 
     FIG. 4 is a detailed view of part of the connector portion of the plug-in circuit board assembly shown in FIG. 2; 
     FIG. 5 is an enlarged cross-sectional view showing a beveled edge region of the connector portion in FIG. 4; 
     FIG. 6 is an enlarged cross-sectional view showing a non-beveled edge region in the connector portion of FIG. 4; 
     FIG. 7 is an enlarged schematic view of a pair of shorting contacts and a connected circuit; 
     FIG. 8 is a perspective view of a back panel with several sockets or receptacles that include both shorting and non-shorting contacts; 
     FIG. 9 is a schematic view illustrating the circuit board of FIGS. 1-6 partially inserted into one of the receptacles of FIG. 8; 
     FIG. 10 is a schematic view illustrating the circuit board of FIGS. 1-6 fully inserted into one of the receptacles of FIG. 8; 
     FIG. 11 illustrates the connector portion of a plug-in circuit board according to a second embodiment of the present invention; and 
     FIG. 12 illustrates the connector portion of a plug-in circuit board according to a third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates the left-hand face of a plug-in circuit board assembly  10  according to a first embodiment of the present invention. Mounted on a generally rectangular, insulating circuit board  12  are integrated circuit (IC) devices  15  and other components that perform the electrical functions of the circuit board assembly  10 . On one side of the circuit board  12  is a faceplate  20  that allows a user to grasp the circuit board assembly  10  during insertion and removal from a socket or receptacle. On the side of the circuit board  12  opposite the faceplate  20  is an integral connector portion  25  that forms an electrical connection to a socket or receptacle (not shown in FIG.  1 ). The connector portion  25  of the circuit board  12  carries a set of conductive fingers  30  that extend toward the edge of the connector portion  25  for electrical connection to contacts carried in the socket or receptacle. In the embodiment shown in FIG. 1, the connector portion  25  of the circuit board  12  includes a non-beveled V-shaped cut-out  35  as well as beveled straight portions  40 . The electrically conductive fingers  30  within the beveled portions  40  connect to conventional (i.e., open or non-shorting) contacts in the receptacle when circuit board  10  assembly is inserted into the receptacle. Some of the electrically conductive fingers  30  may terminate a short distance before the bevel in the areas of the connector portion  25  outside the V-shaped cut-out  35 . This distance may vary for each electrically conductive finger  30  to provide the desired sequence of electrical connections when the circuit board assembly is inserted into the receptacle. The electrically conductive fingers  30  located within the V-shaped cut-out  35  electrically connect to shorting contacts in the receptacle. The electrically conductive fingers  30  within the V-shaped cut-out  35  extend all the way to the edge of the connector portion  25 . As noted above, the edge of the connector portion  25  within the V-shaped cut-out  35  is not beveled. 
     FIG. 2 illustrates the right-hand face of the circuit board assembly  10  shown in FIG.  1 . On this surface, the circuit board  12  includes printed metallic connections  41  and component mounting holes  42  but does not contain IC devices or other electrical components. The corresponding surface of the connector portion  25  contains a second set of electrically conductive fingers  45  which are electrically separate from the first set of conductive fingers  30  illustrated in FIG.  1 . Therefore, the electrically conductive fingers  45  may terminate at different distances from the beveled edges  40  than the corresponding electrically conductive fingers  30  on the opposite face of the circuit board. However, as in the case of FIG. 1, the electrically conductive fingers  45  within the V-shaped cut-out  35  extend all the way to the edge of the connector portion  25  without any bevel. 
     FIG. 3 illustrates the front of the faceplate  20  that is affixed to the side of circuit board  12  opposite the connector portion  25 . The faceplate  20  is substantially wider than the remainder of circuit board  12 , allowing the user to grasp the circuit board assembly  10  and provide the force necessary to insert the circuit board assembly  10  into a socket or receptacle. The faceplate  20  also allows the user to grasp the circuit board assembly  10  during removal of the circuit board assembly  10  from the receptacle. On the faceplate  20  are one or more light emitting diodes (LEDs)  50  to indicate the electrical status of the circuit board assembly  10  after the circuit board assembly  10  is inserted into the socket or receptacle. 
     FIG. 4 is an enlarged view of a part of the right-hand face of the connector portion  25  of the circuit board assembly  10  shown in FIG. 1 (the left-hand face is essentially the same). On the part of the connector portion  25  shown in FIG. 4, the conductive fingers  45  terminate at a distance inward from the insertion edge of the beveled portion  40 . On the part of the connector portion  25  opposite to that shown in FIG. 4, the beveled portion  40  has conductive fingers  45  terminating at varying distances inward from the insertion edge of the connector portion  25  (this can be seen at the bottom of FIGS.  1  and  2 ). This allows for sequential electrical coupling between the conductive fingers  45  of the beveled portion  40  and the corresponding non-shorting contacts of the receptacle, as may be necessary to meet the timing requirements of the circuitry on the circuit board  12 . Unlike the beveled portions  40 , the electrically conductive fingers  45  within V-shaped cut-out  35  extend all the way to the edge of the connector portion  25 . In addition, no bevel exists along the insertion edge of the connector portion  25  within the V-shaped cut-out  35 . This is due to the fact that the electrically conductive fingers  45  within the V-shaped cut-out  35  are required to electrically connect to the respective shorting contacts in the receptacle before the shorting contacts separate from each other. In the illustrated embodiment, the V-shaped cut-out  35  is defined by a recess  55  and by two straight, angled portions  60 . Each of the angled portions  60  preferably forms an angle of between about 5 to 10 degrees with respect to the beveled insertion edges  40 . The insertion edges  40  extend parallel to the side  66  of the circuit board  12  and perpendicular to its insertion direction (the insertion direction is represented by the arrow  67  in FIGS. 1,  2  and  4 ). The angled portions  60  reduce the required insertion force when electrical contact is being made to numerous shorting contacts, because not all of the shorting contacts have to connect to their respective conductive fingers  45  at the same time. Instead, the shorting contacts connect to the electrically conductive fingers  45  sequentially, thus preventing a large insertion force from being required at any one time during insertion of the circuit board assembly  10 . 
     FIG. 5 illustrates a cross-section of the beveled edge portion  40  illustrated in FIG.  4 . Two electrically conductive fingers  30  and  45  are illustrated, since both the left and right faces of the connector portion  25  carry electrically conductive fingers. In other areas of the connector portion  25 , the electrically conductive fingers  30  and  45  terminate at or close to the bevel  70 , where the electrically insulating material of circuit board  12  is exposed. However, in the area shown in FIG. 5, the electrically conductive fingers  30  and  45  terminate a distance behind the bevel  70 . This distance allows sequential electrical connections to be made. The bevel  70  allows for reduced insertion force into conventional (non-shorting) contacts in a receptacle. The arrangement shown in FIG. 5 would not be effective if inserted into shorting contacts because the bevel  70 , which is made of electrically insulating material, would come into contact with and separate the shorting contacts before the electrically conductive fingers  30  and  45  (even if they extend to the edge of the bevel  70 ) could make electrical contact with their respective shorting contacts. 
     FIG. 6 is a cross-sectional view of the connector portion  25  within the V-shaped cut-out  35 . FIG. 6 illustrates the electrically conductive fingers  30  and  45  extending entirely out to the edge  65  of the connector portion  25 . In addition, there is no bevel at the edge  65  of the V-shaped cut-out  35 . The arrangement shown in FIG. 6 is suitable for insertion into shorting contacts within a receptacle because the electrically conductive fingers  30  and  45  will electrically contact the shorting contacts before the shorting contacts are opened. 
     FIG. 7 illustrates a closed set of shorting contacts  72  of the type typically found in a socket or receptacle. Shorting contacts  72  comprise a first flexible metallic contact  75  and a second flexible metallic contact  80 . As illustrated in FIG. 7, the first metallic flexible contact  75  is in electrical contact with the second metallic flexible contact  80 . This electrical contact must not be interrupted unless the corresponding electrically conductive fingers  30  and  45  of the circuit board assembly  10  first make contact with both the first flexible metallic contact  75  and the second flexible metallic contact  80 , respectively. If the first flexible metallic contact  75  separates from the second flexible metallic contact  80  prior to establishing electrical contact with electrically conductive fingers  30  and  45 , the operation of circuit  85  could become disrupted. The arrangement shown in FIG. 5 would be unsuitable for connecting to the shorting contacts  72  in FIG. 7 because the bevel  70 , which is made of an electrically insulating material, would separate the first flexible metallic contact  75  from the second flexible metallic contact  80  prior to electrical contact with both electrically conductive fingers  30  and  45 , respectively. This would be even if the conductive fingers  30  and  45  extended to the edge of the bevel  70  in FIG.  5 . This problem does not occur with the arrangement shown in FIG. 6, since the bevel  70  is omitted. 
     FIG. 8 illustrates a chassis back panel  100  which comprises several sockets or receptacles  105 . Each receptacle  105  comprises four conventional (open) contact sets  110  at each end of the receptacle  105  for electrical connection to the sixteen metallic contact fingers  30  and  45  in the beveled areas  40  of the connector portion  25 . Between the two groups of conventional contact sets  110  are numerous shorting (closed) contact sets  72  for connecting to the metallic contact fingers  30  and  45  adjoining the V-shaped cut-out  35  of the connector portion  25 . All of the conventional contact sets  110  and all of the shorting contact sets  72  lie along a single vertical plane. This allows for sequential connections when the metallic contact fingers on a circuit board that is to be inserted into the receptacle terminate at varying distances from the insertion edge and/or when the connector portion contains a cut-out section. 
     FIG. 9 illustrates the circuit board  10  partially inserted into a receptacle  105  of the back panel  100 . In FIG. 9, the beveled portions  40  of the connector portion  25  are in contact with conventional contacts  110  of the receptacle  105 . Electrically conductive fingers  45  (and electrically conductive fingers  30 , not shown, on the opposite face of the connector portion  25 ) that terminate at or near a beveled edge  40  of connector portion  25  are in electrical contact with conventional contacts  110 . However, because the connector portion  25  has a V-shaped cut-out  35 , some of the electrically conductive fingers  45  and  30  that terminate within the V-shaped cut-out  35  are not yet in electrical contact with their corresponding shorting contacts  72 . As can be seen from FIG. 9, the electrically conductive fingers  45  and  30  that terminate within the V-shaped cut-out  35  of the connector portion  25  of the circuit board  10  are connected sequentially to the shorting contacts  72  as the circuit board  10  is progressively inserted into the receptacle  105 . Since the shorting contacts  72  must be forced apart without the assistance of a beveled insertion edge to connect to the electrically conductive fingers  45  and  30 , it can require substantial insertion force to insert the circuit board  12  into the socket  105 . Therefore, as shown in FIG. 9, the electrically conductive fingers  30  and  45  are connected sequentially, rather than all at once, to the shorting contacts  72  to reduce the insertion force and spread the insertion force out over time. 
     FIG. 10 illustrates the circuit board  10  fully inserted into the receptacle  105 . Each of the conductive fingers  45  and  30  adjoining the V-shaped cut-out  35  of the connector portion  25  is now electrically connected to one of a corresponding pair of shorting contacts  72 . The conductive fingers  30  within the V-shaped cut-out  35  on the left face of circuit board  10  are in electrical contact with flexible metallic contacts  75  of shorting contacts  72 , and the conductive fingers  45  within the V-shaped cut-out  35  on the right face of circuit board  10  are in electrical contact with flexible metallic contacts  80  of shorting contacts  72 . Electrical contact to the shorting contacts  72  has been made without separating the flexible metallic contacts  75  from the flexible metallic contacts  80  prior to contact with the conductive fingers  30  and  45 , respectively. Also, insertion of circuit board assembly  10  into the receptacle  105  has been accomplished without excessive insertion force. 
     The present invention is not limited to the circuit board design shown in FIGS. 1-6. FIG. 11 illustrates a connector portion  200  according to a second embodiment of the present invention. In FIG. 11, the connector portion  200  has a modified V-shaped cut-out area There are two angled regions  210  that have a cross-section similar to FIG.  6  and that connect to shorting contacts similar to those shown in FIG.  7 . However, there are three regions  205  having beveled edges, each with a cross-section similar to that shown in FIG. 5, that connect to conventional (open) contacts. One of the three regions  205  is located between the two angled regions  210  that make contact with the shorting contacts. 
     FIG. 12 illustrates a third embodiment of the present invention. The connector portion  230  comprises a central beveled portion  235  for making electrical connection to conventional contacts in the receptacle. On either side of beveled portion  235  are angled portions  240  that are designed to make contact with shorting contacts in the receptacle. A cross-section through beveled portion  235  would resemble FIG. 5, and a cross-section through either one of the angled portions  240  would resemble FIG.  6 . As with the embodiments of FIGS. 1-6 and  11 , sequential electrical coupling as well as low insertion force can be achieved. In the arrangement of FIG. 12, the shorting contacts are located at the ends of the receptacle and conventional contacts are located in the middle of the receptacle. 
     Other embodiments of the present invention are also possible. For example, the cutout section  35  of the connector portion  25  in FIGS. 1,  2  and  4  may have curved edges rather than the straight edges shown. Similarly, the portions  210  in FIG.  11  and the portions  240  in FIG. 12 may be curved rather than straight. 
     While preferred embodiments of the present invention have been set forth with particularity, it is to be understood that various changes and substitutions are possible without departing from the scope of the claimed invention as set forth in the following claims.