Abstract:
A guide insert is provided for engagement with an edge connector receptacle including a housing having an insertion face and defining a slot for receiving a card edge inserted into the slot along an insertion axis. The guide insert has a body portion that fits over the insertion face of the housing and is formed with first and second aligned slot-form apertures for providing access to first and second segments respectively of the slot defined by the housing. A tab projects from the body portion of the guide insert between the first and second apertures for entering the slot when the body portion engages the insertion face of the housing. The tab has two opposite faces presented towards two opposite sides respectively of the slot.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of application Ser. No. 09/790,365 filed Feb. 21, 2001 now U.S. Pat. No. 6,568,944, the entire disclosure of which is hereby incorporated by reference herein for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a guide insert for PCI (Peripheral Component Interface) connector receptacle. 
     It is common practice to make electrical connections between circuitry on a printed circuit board and a power supply or an external signal source or signal destination by mechanically engaging a connection edge of the board with a mating receptacle and simultaneously establishing electrically conductive connections between an electrically conductive structure at the connection edge of the board and a complementary electrically conductive structure incorporated in the receptacle and including contacts that are electrically connected to the power supply or to the signal source or destination, as the case may be. In one conventional case, the receptacle and electrically conductive structure incorporated therein is known as a card edge connector and the conductive structure at the connection edge of the circuit board is a printed pattern of conductive strips. It is possible to provide connections at a density as high as 38 pins per inch of circuit board edge with this type of connection scheme. 
     The edge connector receptacle typically includes a housing made of electrically insulating material and defining a slot for receiving the connection edge of a circuit board and a linear array of contacts distributed along the slot. Each contact may be in the form of a pair of pins at opposite respective sides of the slot. One form of edge connector receptacle is known as the PCI receptacle, and in its smaller size the PCI receptacle has 60 contacts organized in one group of 11 contacts and one group of 49 contacts spaced apart by an alignment web of the housing. A circuit board that is designed to engage the PCI receptacle is formed with a notch that the alignment web enters when the connection edge of the circuit board is fitted in the slot of the receptacle. Since the alignment web is asymmetrically positioned lengthwise of the slot, there is only one orientation in which the connection edge can be inserted in the slot. 
     The copending application Ser. No. 09/790,365 discloses an arrangement in which two or more circuit boards are mechanically engaged with a single PCI receptacle. Since the PCI receptacle has a single alignment web, use of a single PCI receptacle to make connections to two or more circuit boards necessitates that at least one of the circuit boards should not have a notch that receives the alignment web of the receptacle. Accordingly, there is a possibility that the circuit boards will not be properly positioned in the slot relative to the contacts of the PCI receptacle. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the invention there is provided a guide insert for engagement with an edge connector receptacle including a housing having an insertion face and defining a slot for receiving a card edge inserted into the slot along an insertion axis, the guide insert comprising a body portion that fits over the insertion face of the housing and is formed with first and second aligned slot-form apertures for providing access to first and second segments respectively of the slot defined by the housing, and a tab projecting from the body portion of the guide insert between the first and second apertures for entering the slot when the body portion engages the insertion face of the housing, the tab having two opposite faces presented towards two opposite sides respectively of the slot. 
     In accordance with a second aspect of the invention there is provided a guide insert for engagement with an edge connector receptacle including a housing having an insertion face and defining a slot for receiving a card edge inserted into the slot along an insertion axis, the guide insert comprising a body portion that fits over the insertion face of the housing and is formed with first and second aligned slot-form apertures for providing access to first and second segments respectively of the slot defined by the housing, and at least first and second tabs projecting from the body portion of the guide insert for entering the slot when the body portion engages the insertion face of the housing, each tab having two opposite faces presented towards two opposite sides respectively of the slot, and wherein the first and second tabs are at opposite respective ends of the first aperture. 
     In accordance with a third aspect of the invention there is provided an article of manufacture comprising an edge connector receptacle including a housing having an insertion face and defining a slot for receiving a card edge inserted into the slot along an insertion axis, and a guide insert for engagement with the receptacle, the guide insert comprising a body portion that fits over the insertion face of the housing and is formed with first and second aligned slot-form apertures providing access to first and second segments respectively of the slot defined by the housing, and a tab projecting from the body portion of the guide insert between the first and second apertures into the slot defined by the housing, the tab having two opposite faces presented towards two opposite sides respectively of the slot. 
     In accordance with a fourth aspect of the invention there is provided an article of manufacture comprising an edge connector receptacle including a housing having an insertion face and defining a slot for receiving a card edge inserted into the slot along an insertion axis, and a guide insert for engagement with the receptacle, the guide insert comprising a body portion that fits over the insertion face of the housing and is formed with first and second aligned slot-form apertures providing access to first and second segments respectively of the slot defined by the housing, and at least first and second tabs projecting from the body portion of the guide insert into the slot defined by the housing, each tab having two opposite faces presented towards two opposite sides respectively of the slot, and wherein the first and second tabs are at opposite respective ends of the first aperture. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which 
     FIG. 1 is a partial perspective view of an item of electronic equipment in accordance with the present invention and illustrates a circuit board assembly, 
     FIG. 2 is an enlarged perspective exploded view of a PCI receptacle that is included in the equipment shown in FIG. 1, 
     FIG. 3 is a perspective view of the PCI receptacle insert shown in FIG. 2, viewed from the rear, and 
     FIG. 4 is an enlarged sectional view of the receptacle and insert. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates a frame having two opposite side walls  10  (only one of which is shown) each provided with five horizontal guide channels  14  for receiving respective longitudinal edges of printed circuit boards  18  (only one of which is shown). Each circuit board  18  is part of a circuit board assembly  20  including the circuit board  18  (the main circuit board) and two auxiliary circuit boards  22 A.  22 B (referred to generally as boards  22 ). The frame has a rear wall or bulkhead  26  formed with five rows of circular holes  28 . A male/female BNC feed through  30  is mounted in each hole  28  with the male portion of the feed through presented towards the interior of the frame and the female portion presented towards the exterior, for receiving a BNC plug attached to a cable. 
     Several BNC receptacles  34  are attached to the main circuit board  18  on the upper side thereof. Each BNC receptacle has a signal lead  36  which is connected through conductor traces (not shown) of the circuit board to at least one electronic component on the circuit board. When the circuit board assembly  20  is inserted in the frame, the BNC receptacles  34  of the main circuit board engage respective feed throughs  30  on the bulkhead, providing a uniform characteristic impedance path from the circuit board to the female portion of the feed through. 
     Two PCI card edge connector receptacles  38 A,  38 B (referred to generally as receptacles  38 ) are firmly attached to the bulkhead  26 . The PCI receptacles are vertically oriented and are positioned so that the BNC feed throughs  30  are between the two PCI receptacles  38 . 
     Each PCI receptacle  38  includes a body  40  of electrically insulating material which defines a slot  44  (FIG. 2) for receiving a connection edge of a printed circuit board. Sixty contacts, each composed of a pair of conductive pins  46  (FIG.  4 ), are mounted in the body of the PCI receptacle for engaging conductive strips on the connection edge of the circuit board. The tips of the pins are located in respective recesses  48  and the walls of the recesses prevent shorting of the pins of adjacent contacts. 
     The body  40  of the PCI receptacle includes an alignment web  42  which divides the slot  44  into two segments. The alignment web normally engages a notch in the edge of the circuit board to ensure that the connection edge is inserted in the proper orientation. The shorter segment of the slot accommodates 11 contacts and the longer segment accommodates 49 contacts. 
     As shown in FIG. 2, the shorter segment of the slot  44  is at the top of the receptacle. The adjacent contacts of the upper group of 11 contacts are at a uniform center-to-center spacing S and the adjacent contacts of the lower group of 49 contacts are at the same center-to-center spacing. The bottom contact in the upper group and the top contact in the lower group are at a center-to-center spacing  2 S. Thus, it is convenient to refer to the contacts as being at positions  1 - 11  and  13 - 61 , position  12  being occupied by the alignment web. 
     The two auxiliary circuit boards  22 A,  22 B are attached to the main circuit board  18  adjacent the longitudinal edges respectively. Each auxiliary circuit board  22  is perpendicular to the main board and extends parallel to the longitudinal edges and has a connection edge that extends beyond the connection edge of the main board approximately as far as the BNC receptacles. The auxiliary board is provided adjacent its connection edge with contact strips  4  of width and spacing for engagement with the contacts of a PCI receptacle. The contact strips are electrically connected to connector runs on the main board through conductive leads  52  that are soldered both to the auxiliary board and to the main board and thus serve to stabilize the auxiliary board relative to the main board. 
     The auxiliary boards  22 A,  22 B are positioned relative to the main board  18  and the PCI receptacles  38 A,  38 B are positioned relative to the guide channels  14  so that when the circuit board assembly  20  is placed in the frame, with the edges of the main board  18  in the channels  14 , the BNC receptacles  34  on the main board are aligned with the feed throughs  30  in one row of holes  28  and the connection edges of the auxiliary boards  22 A,  22 B are aligned with the slots of the PCI receptacles  38 A,  38 B respectively. When the circuit board assembly is pushed home to the rear of the frame, the BNC receptacles  34  engage the feed throughs  30  and the connection edges of the auxiliary boards enter the slots of the PCI receptacles. Electrical contact is made between the contact strips of the auxiliary board  22 A and nine of the contacts of the PCI receptacle  38 A. The auxiliary board  22 B engages the PCI receptacle  38 B in analogous manner. Consequently, the auxiliary boards and the mating PCI receptacles provide edge connection capacity for 18 additional connections to the main board, and may be used to provide control signals and power to the electronic components on the main board. 
     FIG. 1 also illustrates a guide insert  64  for guiding the connection edges of the auxiliary circuit boards into the slot of the PCI receptacle. The guide insert  64  comprises an injection molded body of electrically insulating synthetic polymer material defining five slots, each of which spans nine contact positions. Six tabs  66 - 76  project from the body of the insert and are inserted in the slot of the PCI receptacle for holding the insert  64  in position relative to the body  40 . It will be seen that each of the tabs has two opposite surfaces that are reticulated in accordance with the reverse image of the PCI contact pins. When the tabs are inserted in the slot of the PCI receptacle, at least one pair of contact pins slide in respective grooves of each tab so that the insert is accurately positioned lengthwise of the slot relative to the remaining contact pins and is securely held against disengagement from the PCI receptacle. The tabs  66 ,  68 ,  74  and  76  are positioned so that there is only one orientation in which the guide insert can be installed in the slot of the PCI receptacle, and in this orientation the tab  68 , which has only one pair of opposed grooves, is immediately below the alignment web  42  and its grooves receive the pins of the contact at position  13  and isolate that contact. 
     The tab  66  has two grooves on each side and enters the slot at the very top of the receptacle, thus isolating the contacts at positions  1  and  2  of the connector. The tabs  70  and  72  each have four pairs of opposed grooves. The tab  70  isolates the contacts at positions  23 - 26  and the tab  72  isolates the contacts at positions  36 - 39 . The tab  74  has three pairs of grooves and is positioned to isolate the contacts at positions  49 - 51 , and the tab  76  has just one pair of grooves and is positioned to isolate the contact at position  61 . It will thus be seen that through cooperation of the tabs  66 - 76  and the alignment web  42  of the PCI receptacle, the sixty contacts of the PCI receptacle are divided into five groups each of which contains nine contiguous, uniformly spaced contacts. 
     The entrance to each slot of the guide insert is surrounded by four guide surfaces  80  for guiding the connection edges of the auxiliary circuit boards into the proper respective positions in the slot of the PCI receptacle. 
     For added security, a strip of double sided adhesive tape  78  may be applied to the rear surface of the guide insert prior to installation in the PCI receptacle. The adhesive tape adheres to the insertion face of the housing and prevents inadvertent removal of the guide insert. 
     It will be appreciated that the invention is not restricted to the particular embodiment that has been described, and that variations may be made therein without departing from the scope of the invention as defined in the appended claims and equivalents thereof. Unless the context indicates otherwise, a reference in a claim to the number of instances of an element, be it a reference to one instance or more than one instance, requires at least the stated number of instances of the element but is not intended to exclude from the scope of the claim a structure or method having more instances of that element than stated.