Abstract:
A socket assembly is provided having a socket cover slidably mounted to a socket base. The socket cover includes a cam retention area containing a drive plate and a cam lever rotatably engaging the socket cover, socket base and drive plate. The cam rotatably engages, and applies torque forces to, the socket cover, plate, and socket base to slide the socket cover with respect to the socket base. The drive plate and the cam retention area include torque transfer members that engage one another. The torque transfer members are located at intermediate points with the drive plate and the cam retention area.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention generally relates to a socket cover that is cam actuated. More particularly, the present invention relates to a socket cover having a cover plate configured to absorb torque induced by cam rotation.  
           [0002]    Many large electronic devices, such as computers, use sockets to connect different electronic components. For example, pin grid array (PGA) sockets are used to connect electronic packages, such as processors, to printed circuit boards. PGA sockets facilitate electrical communication between a large number of pins on the processor and contacts on the circuit board. PGA sockets may utilize a plastic socket cover that is slidably movable on a plastic socket base between open and closed positions. Generally, a cam mechanism is used to drive the cover and base between open and closed positions.  
           [0003]    The socket cover has an array of pin holes configured to match an array of pins on the processor. Similarly, the socket base has an array of pin receiving chambers configured to accept the array of pins on the processor and connected to contact pads on the circuit board. The processor is mated to the socket by first placing the processor such that its pins slide into the pin holes of the socket cover. With the socket cover in the open position, the processor pins pass through the pin holes of the socket cover into the pin receiving chambers of the socket base, but are not yet electrically connected to the pin receiving chambers of the socket base. A cam mechanism on the socket is rotated to slide the socket cover to the closed position which causes the processor pins to electrically connect to contacts in the pin receiving chambers in the socket base.  
           [0004]    The cam mechanism includes a plate that is retained in a recessed area on the bottom of the socket cover between the socket cover and the socket base. The socket cover, plate, and socket base each have apertures therethrough that align with one another to receive a cam shaft. The cam shaft is situated in a channel on the socket cover and extends through the socket cover, plate and socket base. The cam shaft is rotated to slide the socket cover to the closed position on the socket base to electrically connect the processor pins to contacts in the pin receiving chambers in the socket base. More specifically, as the cam shaft is rotated to cause the sliding movement between the socket cover and socket base, the cam shaft drives the plate relative to the socket base. The plate is held firmly in the recessed area in the socket cover which in turn causes the socket cover to move relative to the socket base. The plate is used to absorb the torque forces created by the cam shaft to prevent the socket cover from cracking.  
           [0005]    However, the conventional sockets suffer from several drawbacks. As the cam shaft rotates, it generates torque forces. As noted above, the plate is positioned in the recessed area of the socket cover to absorb much of the torque forces and distribute the torque forces throughout the plate in order to prevent the torque forces from cracking the thin plastic socket cover. However, the torque forces cause the plate to twist or “rotate” within the recessed area such that certain angled points on the plate press directly against the wall segments of the socket cover. Thus, the torque forces are redistributed at high stress concentrations at certain points along the wall segments which cause strains and cracks in the socket cover to develop over time with repeated use. Once cracks occur in the socket cover, the plate moves relative to the socket cover thereby reducing the amount of motion transferred from the cam to the socket cover. Hence, the cam shaft cannot properly engage the socket cover to slidably move the socket cover the full desired distance relative to the socket base.  
           [0006]    A need exists for a socket cover that addresses the above noted problems and others experienced heretofore.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    Certain embodiments of the present invention include an electrical socket assembly having a socket cover slidably mounted to a socket base. The socket cover includes a cam retention area containing a drive plate and a cam lever rotatably engaging the socket cover, socket base and drive plate. The cam lever rotatably engages, and applies torque forces to, the socket cover and socket base to slide the socket cover with respect to the socket base. The drive plate and the cam retention area include torque transfer members that engage one another. The torque transfer members are located at intermediate points with the drive plate and the cam retention area. 
       
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 illustrates a top isometric view of a socket assembly formed according to an embodiment of the present invention.  
         [0009]    [0009]FIG. 2 illustrates a bottom isometric view of a socket assembly formed according to an embodiment of the present invention.  
         [0010]    [0010]FIG. 3 illustrates an exploded isometric view of the socket assembly of FIG. 1.  
         [0011]    [0011]FIG. 4 illustrates an isometric view of a drive plate formed according to an embodiment of the present invention.  
         [0012]    [0012]FIG. 5 illustrates a bottom isometric view of a socket cover formed according to an embodiment of the present invention.  
         [0013]    [0013]FIG. 6 illustrates a bottom isometric view of a socket cover with the drive plate inserted according to an embodiment of the present invention. 
     
    
       [0014]    The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    [0015]FIGS. 1 and 2 illustrate isometric views of a socket assembly  10  formed according to an embodiment of the present invention. The socket assembly  10  includes an insulated socket cover  14  slidably mounted to an insulated socket base  18 . The socket base  18  has a body  70  that carries an array of receptacle contacts  22  (FIG. 2) extending therethrough. The socket cover  14  has an array of pin holes  26  (FIG. 1) that are aligned to be positioned above the array of receptacle contacts  22 . In operation, the socket assembly  10  is connected to an electronic component such as a circuit board (not shown) such as by soldering the receptacle contacts  22  to contact pads or traces on the circuit board. A processor (not shown) having an array of pins is then positioned on top of the socket cover  14  such that the pin holes  26  receive the pins. The pins of the processor extend into and engage the receptacle contacts  22  in the body  70  of the socket base  18 .  
         [0016]    The socket cover  14  has a generally rectangular body  66  with a cam portion  30  extending from an end thereof. The cam portion  30  has a semicircular channel  34  notched in the socket cover  14  to receive a lever  62  and a cylindrical cam shaft  38 . The cam shaft  38  extends through the body  66  of the socket cover  14  and the body  70  of the socket base  18 . The cam shaft  38  may be formed of metal or another suitably hard material.  
         [0017]    The socket assembly  10  as shown in FIG. 1 is in an unlocked position where the socket cover  14  and socket base  18  are aligned such that the pins of the processor are not bound in the pin holes  26  of the socket cover  14 . As the cam shaft  38  is rotated in the direction of arrow A (FIG. 1) about a rotational axis  75 , the cam shaft  38  indirectly engages the body  66  of the socket cover  14  and directly engages the body  70  of the socket base  18 . The cam shaft  38  pushes the body  66  of the socket cover  14  in the direction of arrow B with respect to the body  70  of the socket base  18  to cause a relative horizontal shift. As the socket cover  14  and the socket base  18  move, they cause the pin holes  26  to shift out of alignment with the receptacle contacts  22  and bind the processor pins within the socket cover  14 .  
         [0018]    [0018]FIG. 3 illustrates an exploded isometric view of the socket assembly  10 . On the bottom side of the socket cover  14 , the cam portion  30  includes a recessed area  42  having a trapezoidal shape that receives a trapezoidal shaped drive plate  46 . The drive plate  46  may be formed of metal or another suitably hard material. The cam portion  30  has a circular cam aperture  50  and the drive plate  46  has an oval cam aperture  54 . The socket base  18  also has a cam portion  58  that presses up flush against the drive plate  46  when the socket assembly  10  is fully assembled. The cam portion  58  of the socket base  18  also has a circular cam aperture  60 . When the socket assembly  10  is fully assembled, the cam apertures  50 ,  54  and  60  of the socket cover  14 , drive plate  46 , and socket base  18 , respectively, are all aligned and receive the cam shaft  38 .  
         [0019]    The cam shaft  38  includes cylindrical upper and lower portions  35  and  39 . The upper portion  35  has a larger radius than the lower portion  39 . The upper portion  35  overlaps the lower portion  39  along the perimeter of the lower portion  39  except where the upper and lower portion  35  and  39  share a common wall  37  at a point in their respective perimeters. The upper portion  35  is received within the cam apertures  50  and  54  and the lower portion  39  is received within the cam aperture  60 . As the cam shaft  38  is rotated about the rotational axis  75  (FIG. 1) in the direction of arrow A (FIG. 1), the larger-radiused upper portion  35  engages the drive plate  46  and moves the drive plate  46 , and thus the socket cover  14 , in the direction of arrow B (FIG. 1) relative to the socket base  18  as the lower portion  39  rotates within the cam aperture  60 .  
         [0020]    [0020]FIG. 4 illustrates an isometric view of the drive plate  46 . The drive plate  46  is rhomboid or trapezoidal in shape and is defined by an outer wall  64 , an inner wall  68  and opposed side walls  74 . The side walls  74  form acute angles with the inner wall  68  at first and second inner comers  78  and  82 , respectively, and obtuse angles with the outer wall  64  at first and second outer comers  86  and  90 . Optionally, the drive plate  46  may be shaped differently, such as circular, rectangular, star-shaped, triangular, hexagonal, rhomboid, pentagonal and the like. A U-shaped notch  94  is cut into the drive plate  46  along the outer wall  64  to receive a keying feature  98  (FIG. 5) in the recessed area  42  (FIG. 3). The oval shaped cam aperture  54  is formed near the center of the drive plate  46  and has parallel opposed segments  102  defining the narrowest portion of the cam aperture  54 . The segments  102  engage the upper portion  35  (FIG. 3) of the cam shaft  38  (FIG. 3). The drive plate  46  also includes circular post holes  106  situated on opposite sides of the cam aperture  54 .  
         [0021]    [0021]FIG. 5 illustrates a bottom isometric view of the socket cover  14 . The recessed area  42  is bordered by an outer wall  110 , an inner wall  114 , and opposed side walls  118 . The side walls  118  intersect the inner wall  114  at first and second inner comers  122  and  126 , respectively, and intersect the outer wall  110  at first and second outer comers  130  and  134 , respectively. Cylindrical support posts  138  are formed with, and extend from, a recessed surface  40  of the recessed area  42 . The support posts  138  are located on opposite sides of the cam aperture  54 . A keying feature  98  extends from the outer wall  110  into the recessed area  42 .  
         [0022]    [0022]FIG. 6 illustrates a bottom isometric view of the socket cover  14  with the drive plate  46  inserted. During assembly, the drive plate  46  is press fitted into the recessed area  42  such that the keying feature  98  of the recessed area  42  is received in the notch  94  (FIG. 4) of the drive plate  46  and the support posts  138  of the recessed area  42  are received within the post holes  106  (FIG. 4) of the drive plate  46 . The support posts  138  and post holes  106  form a close tolerance with one another. The drive plate  46  is flush with a bottom surface  142  of the body  66  of the socket cover  14 . The first and second inner comers  78  and  82  of the drive plate  46  are positioned proximate the first and second inner comers  122  and  126 , respectively, of the recessed area  42 . The first and second outer comers  86  and  90  of the drive plate  46  are positioned proximate the first and second outer comers  130  and  134 , respectively, of the recessed area  42 .  
         [0023]    In operation, the cam shaft  38  (FIG. 3) is rotated within the cam aperture  54  of the drive plate  46  and the upper portion  35  abuts against the segments  102  to apply torque forces against the drive plate  46 . The drive plate  46  distributes the torque forces throughout points of contact between the drive plate  46  and the recessed area  42  of the socket cover  14 . These points of contact include where the support posts  138  engage the post holes  106  in the drive plate  46  on opposite sides of the cam aperture  54  which prevent the drive plate  46  from sliding or “rotating” within the recessed area  42 . For example, if the cam shaft  38  is rotated about the rotational axis  75  (FIG. 1) in the direction of arrow A (FIGS. 1 and 5), the cam shaft  38  induces a rotational force on the drive plate  46  also in the direction of arrow A (FIG. 5) such that the first inner comer  78  of the drive plate  46  is pushed toward the first inner comer  122  of the recessed area  42  and the second outer corner  90  of the drive plate  46  is pushed toward the second outer comer  134  of the recessed area  42 . However, the support posts  138  absorb the rotational forces carried by the drive plate  46  and prevent the drive plate  46  from “rotating”, which in turn prevents any concentration of force on the first inner and second outer corners  122  and  134  of the recessed area  42 . Thus, the support posts  138  engage the drive plate  46  to prevent a concentration of force from being applied to the inner, outer, or side walls  114 ,  110 , and  118  of the recessed area  42  at any one point that would result in strains and cracks in the socket cover  14 .  
         [0024]    Additionally, the trapezoidal shape of the drive plate  46  and the recessed area  42  prevent large concentrations of force from being applied along the outer wall  110  of the recessed area  42 . A small acute angle at the first and second inner corners  78  and  82  of the drive plate  46  and the corresponding first and second inner corners  122  and  126  of the recessed area  42  serve to better distribute forces from the drive plate  46  along the thicker side walls  118  of the recessed area  42  and reduce the distribution of forces along the outer wall  110 . For example, decreasing the size of the angle of the first inner corner  78  results in a longer side wall  74  of the drive plate  46  and thus a greater surface area for the side wall  74  of the drive plate  46  to engage the side wall  118  of the recessed area  42 . By increasing the surface area of engagement, the forces carried by the drive plate  46  are distributed to the side wall  118  over a greater area such that high concentrations of force are not applied to any particular point along the side wall  118  and less force is applied to the outer wall  110 .  
         [0025]    In one alternative embodiment, the support posts  138  may be located in different positions within the recessed area  42  and corresponding post holes  106  may be located in different positions in the drive plate  46 . For example, the support posts  138  may be located further from each other and closer to the first and second inner corners  122  and  126  and the corresponding post holes  106  located further from each other and closer to the first and second inner corners  78  and  82 . Conversely, the support posts  138  may be located closer to each other alongside the cam aperture  50  and the corresponding post holes  106  located closer to each other alongside the cam aperture  54 .  
         [0026]    In another alternative embodiment, the recessed area  42  may have more than two support posts  138  received in corresponding post holes  106  in the drive plate  46 . For example, the recessed area  42  may have four smaller support posts  138  situated about the cam aperture  50 . Similarly, the drive plate  46  would have corresponding smaller post holes  106  situated about the cam aperture  54  to receive the support posts  138 .  
         [0027]    In another alternative embodiment, the recessed area  42  and the corresponding drive plate  46  may have any variety of different shapes and sizes. For example, the recessed area  42  and drive plate  46  could have square, triangular, rounded, rhomboid, hexagonal, star-shaped or any other geometric or amorphous, non-symmetric shapes. Additionally, the recessed area  42  and the drive plate  46  can vary in sizes depending on the additional strength required by the drive plate  46  and the size and number of support posts  138  needed to support the drive plate  46 . Different sized and shaped drive plates  46  and recessed areas  42  may be appropriate to limit force concentrations on particular points along the inner, outer and side walls  114 ,  110 , and  118  of the recessed area  42 .  
         [0028]    In another alternative embodiment, the support posts  138  and the corresponding post holes  106  may be any variety of size and shape. For example, the support posts  138  and post holes  106  may be square, rectangular, triangular, star-shaped, hexagonal, or any other geometric or amorphous, non-symmetric shape. Different sized and shaped support posts  138  may be appropriate for different torque requirements and socket cover  14  uses.  
         [0029]    In another alternative embodiment, the support posts  138  extend from the drive plate  46  and the post holes  106  are located in the recessed area  42 . Thus, the drive plate  46  is fitted into the recessed area  42  with the support posts  138  extending into the body  66  of the socket cover  14 . Such an embodiment may be used where stronger support posts  138  formed of metal or a similarly strong and durable substance are needed to withstand torque forces applied to the drive plate  46 .  
         [0030]    While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.