Abstract:
A driving mechanism is provided for a socket which comprises a cover movably mounted on a base between an open status and a closed status. The driving mechanism comprises a first reception space defined in the cover, a second reception space defined in the base and communicating with the first reception space, a driving device having an upper portion retained in the first reception space of the cover and selectively operative to move the cover in opposite directions, and a lower portion connected to the upper portion and having a positioning member operatively switchable between a first position and a second position in the second reception space of the base. The upper portion of the driving device moves the cover between the open status and the closed status depending on the relative position of the positioning member in the second reception space.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a driving mechanism of a ZIF socket and the socket using the same, and especially to a single-point driving mechanism which drives a cover of the socket to move with respect to a base thereof in opposite directions from one driving point thus rendering the socket in either a closed status or an open status. 
     2. The Prior Art 
     Conventional ZIF PGA sockets normally comprise a cover defining a plurality of upper passageways therein and slidably engaging with a base having a corresponding number of lower passageways retaining contacts therein. The upper passageways and the lower passageways are in constant communication with each other when the cover is moved with respect to the base. A cam is received in a space defined between the cover and the base and operative to move the cover with respect to the base thereby positioning the socket at either an open status ready for insertion of pins of a CPU package or a closed status forcing the pins of the CPU package to abut against the corresponding contacts. When the socket is in the open status, the pins of the CPU package are inserted into the upper passageways and the lower passageways with a substantially zero insertion force, but are not in electrical contact with the contacts retained in the lower passageways. The cam is then operated to drive the cover to move laterally relating to the base thereby urging the pins of the CPU package to electrically connect with the contacts of the base. U.S. Pat. No. 5,730,615 which belongs to the same assignee of this application has disclosed a driving mechanism for driving the cover to move with respect to the base from a single side of the socket by inserting a screwdriver into slots defined in the cover and the base and pivoting the screwdriver to drive the cover. This driving mechanism may be easily manipulated for moving the cover in one direction but it is difficult to be manipulated in opposite direction. This is because the slots may be vertically in alignment with each other when the socket is in an open status (or closed status) but they are not vertically in alignment with each other when the socket is in a closed status (or open status). The user has to insert the screwdriver to the two slots in a slanted manner thus causing difficulty when the two slots are not vertically in alignment with each other. Moreover, when the user pivots the screwdriver he (she) may be prohibited by peripheral components nearby thus causing difficulty. 
     It is requisite to provide a new driving mechanism which is easily manipulated without much operation space. 
     SUMMARY OF THE INVENTION 
     The primary purpose of the present invention is to provide an improved driving mechanism for a socket which is easily manipulated and only needs relatively small operation space. 
     In accordance with one aspect of the present invention, a driving mechanism is provided for a socket which comprises a cover movably mounted on a base. The driving mechanism comprises an upper opening and a lower opening defined in the cover, wherein the lower opening is in communication with the upper opening. A reception space is defined in the base and communicates with the lower opening of the cover. A driving cam comprises an upper circular portion rotatably received in the upper opening of the cover, a middle cam portion rotatably retained in the lower opening of the cover, and a lower circular portion rotatably retained in the reception space of the base, wherein the upper circular portion and the lower circular portion are co-axial to each other. The cover is movable along a first direction with respect to the base when the lower circular portion of the driving cam is rotated counter-clockwise within a predetermined angular range, while the cover is movable along a second direction opposite to the first direction when the lower circular portion of the driving cam is rotated clockwise within the predetermined angular range. 
     In accordance with another aspect of the present invention, a driving mechanism is provided for a socket which comprises a cover movably mounted on a base. The driving mechanism comprises a first reception space defined in the cover, a second reception space defined in the base and communicating with the first reception space, a driving cam having an upper cam portion rotatably retained in the first reception space of the cover and a lower circular portion connected to the upper cam portion and rotatably retained within a predetermined angular range in the second reception space of the base. The upper cam portion of the driving cam is selectively rotated either clockwise or counter-clockwise within the predetermined angular range in the first reception space thereby driving the cover to translate on the base along one of opposite directions. 
     In accordance a further aspect of this invention, a driving mechanism is provided for a socket which comprises a cover movably mounted on a base between an open status and a closed status. The driving mechanism comprises a first reception space defined in the cover, a second reception space defined in the base and communicating with the first reception space, driving means having an upper portion retained in the first reception space of the cover and selectively operative to move the cover in opposite directions, and a lower portion connected to the upper portion and having a positioning member operatively switchable between a first position and a second position in the second reception space of the base. Wherein the upper portion of the driving means moves the cover from the open status to the closed status when the positioning member is switched from the first position to the second position, and the upper portion of the driving means moves the cover from the closed status to the open status when the positioning member is switched from the second position to the first position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a perspective view of a base of a connector in accordance with the present invention; 
     FIG. 1B is a perspective view of the base of FIG. 1A taken from a different angle; 
     FIG. 2A is a perspective view of a cover of the connector in accordance with the present invention; 
     FIG. 2B is a perspective view of the cover of FIG. 1A taken from a different angle; 
     FIG. 3A is perspective view of a driving cam in accordance with the present invention; 
     FIG. 3B is perspective view of the driving cam of FIG. 3A taken from a different angle; 
     FIG. 3C is a top plan view of the driving cam; 
     FIG. 4 is a perspective view showing the driving cam is installed in the base; 
     FIG. 5 is a fully assembled view of the cover, the driving cam and the base; and 
     FIGS. 6A to  6 C are operational schematic views of the driving cam with respect to the cover. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1A, a base  1  of a connector in accordance with the present invention comprises a housing  11  and a head  12  extending from the housing  11 . The housing  11  has two sliders  15  formed in opposite sides thereof and defines a plurality of passageways  100  receiving contacts (not shown) therein for electrically and mechanically connecting to CPU pins (not shown) inserted thereinto. The head  12  defines a groove  16  in opposite sides thereof and a rib  161  extending from each groove  16 . A reception cavity  110  is defined in the head  12 , with two inner protrusions  111  extending from an inner periphery of the reception cavity  110 . A cutout  112  is defined in a periphery portion of the reception cavity  110  as a gate therefore the cavity  110  is accessible from a horizontal direction in addition to a vertical direction. A resilient beam  13  is formed on the head  12  and includes an angled end  131  laterally extending into the reception cavity  110  through the cutout  112 . The resilient beam  13  herein is integrally extended from a portion of the head  12 . Alternatively, the resilient beam  13  may be connected to the portion of the head  12  by interference or the like as well known. Actually, the resilient beam  13  may be made of metal plate and connected to the portion of the head  12  by interference. Also referring to FIG. 1B, four standoffs  17  are formed at the bottom of the base prevent solder ball (not shown) attached to the contacts from being collapsed. 
     Referring to FIGS. 2A and 2B, a cover  2  adapted to be slidably engaged with the base  1  comprises a body portion  21  and a head  22  extending from the body portion  21 . The head  22  has opposite inner walls  23  thereby defining a space  24  therebetween for movably receiving the head  12  of the base  1  therein. The body portion  21  has a plurality of conic holes  200  formed therein for receiving CPU pins (not shown) and each conic hole  200  is maintained in constant communication with a corresponding passageway  100  of the base  1  when the cover  2  is assembled to and moved on the base  1 . Two guiding arms  211  extend from opposite sides of the body portion  21  and each guiding arm  211  has two guiding recesses  28  formed in inner surface thereof for slidably receiving the sliders  15  of the base  1  when the cover  2  is assembled to the base  1 . A stopping bar  27  extends from a bottom surface of the body portion  21  substantially in alignment with rear side thereof for limiting a slidable distance of the cover  2  with respect to the base  1 . The stopping bar  27  together with the guiding arms  211  also constitute reinforcing means preventing the cover  2  from warpage. The head  22  of the cover  2  has two resilient clamps  26  extending downward for slidably engaging with the ribs  161  of the base  1  when the cover  2  is assembled to the base  1 . An upper opening  20  and a lower opening  220  are defined in the head  22  and communicated with each other. The upper opening  20  has an ellipse-like shape and the lower opening  220  has a rectangle-like shape. 
     Referring to FIGS. 3A to  3 C, a driving cam  3  comprises an upper circular portion  31  connected to a middle cam portion  32  connected to a lower circular portion  33 . A tool reception hole  310 , herein a hexagonal hole, is defined through the driving cam  3  allowing an external tool (not shown), such as a hexagonal wrench to operate therewith for rotate the driving cam  3 . An indication groove  311  is defined along a radial direction around the tool reception hole  310  for indicating the rotated angle of the driving cam  3 . The tool reception hole  310  may be alternatively formed as a slit or a cross shape allowing other screwdrivers to operate therewith. The lower circular portion  33  has a first positioning groove  331  and a second positioning groove  332  formed on a periphery thereof and also an arcuate protrusion  333  extending from the periphery. Particularly referring to FIG. 3C, the upper circular portion  31  and the lower circular portion  33  are co-axial to each other. 
     Also referring to FIG. 6A, the middle cam portion  32  has a first periphery portion  32 A in alignment with one fourth of the periphery of the lower circular portion  33  and substantially located in the second quadrant of the X-Y axes, a second periphery portion  32 B in alignment with one fourth of the periphery of the upper circular portion  31  and substantially located in the fourth quadrant of the X-Y axes, and a third periphery portion  32 C and a fourth periphery portion  32 D connected between the first and second periphery portions  32 A,  32 B and substantially located in the first and third quadrants of the X-Y axes, respectively. It can be noted that third periphery portion  32 C and the fourth periphery portion  32 D respectively located in the opposite first and third quadrants of the X-Y axes, are respectively defined with two proper curves generally symmetrical with each other to an imaginary angular bisector L along the second and fourth quadrants of the X-Y axes wherein each curve defines a first end point with a larger diameter and a second end point with a smaller diameter relative to the rotation center, i.e., the intersection point of the X-Y axes. 
     Referring to FIG. 4, the lower circular portion  33  of the driving cam  3  is assembled into reception cavity  110  of the base  1 , with the upper circular portion  31  and the middle cam portion  32  remaining out of the reception cavity  110 , wherein the lower circular portion  33  is rotatable within substantially a 90-degree range in the reception cavity  110  and the angled head  131  of the resilient beam  13  keeps in contact with a periphery portion of the lower circular portion  33  when the lower circular portion  33  rotates. FIG. 4 particularly shows that the lower circular portion  33  is rotated to an extreme of the 90-degree range, wherein the arcuate protrusion  333  is stopped by one of the inner protrusions  111  of the reception cavity  110  of the base  1 , and the angled head  131  of the resilient beam  13  is received in the first positioning groove  331  of the lower circular portion  33 . 
     Referring to FIG. 5, after the driving cam  3  is assembled into the reception cavity  110  of the base  1 , the cover  2  may be assembled on the base  1 , with the upper circular portion  31  and the middle cam portion  32  of the driving cam respectively received in the upper opening  20  and the lower opening  220  and the tool reception hole  310  exposing to external allowing an external tool (not shown) to rotate the driving cam  3  thereby. When the cover  2  is driven by the driving cam  3  to move on the base  1 , the upper opening  20  due to the ellipse-like shape thereof can be maintained straight by the upper circular portion  31  retained therein thereby guaranteeing the cover  2  to move straight along a longitudinal axis thereof without deflection. 
     Referring to FIGS. 6A to  6 C, an operational relation between the middle cam portion  32  and the cover  2  (herein schematically represented by the lower opening  220  shown by phantom line) is illustrated, wherein two axes X and Y are used to indicate the rotation of the middle cam portion  32  and the intersection point of the X and Y axes is in the co-axis of the upper circular portion  31  and the lower circular portion  33 . From the sequence of FIGS. 6A to  6 C, the middle cam portion  32  together with the lower circular portion  33  and the upper circular portion  31  (not shown herein but can be referred to FIG. 4) are rotated counter clockwise for substantially 90 degrees, thereby rendering the cover  2  to move along a first direction for a distance D. It is because the engagement between the curve  32 D and the corresponding edge  2202  by the opening  220 , is changed from the smaller diameter end point to the larger diameter end portion. Similarly, the middle cam portion  32  can be rotated clockwise from a reverse sequence thereby rendering the cover  2  to move along a second direction opposite to the first direction for the same distance D by means that the engagement between the curve  32 C and the corresponding edge  2201  by the opening  220 , is changed from the smaller diameter end point to the larger diameter end point. 
     It is noted that the driving cam  3  is retainably received within the cavity  110  of the base  1 , the upper opening  20  and the lower opening  220  of the cover  2  wherein the bottom face of the lower portion  33  is seated on the supporting surface  110 ′ of the base  1 , and the upper face of the lower portion  33  and the upper face of the middle portion  32  respectively engaged with the corresponding restraint portions (not labeled) around the lower opening  220  and the upper opening  20  of the cover  2 , so as to restrain the vertical movement of the cam  3  within the connector. 
     While the present invention has been described with reference to a specific embodiment, the description is illustrative of the invention and is not to be construed as limiting the invention. For example, the upper circular portion  31  of the driving cam  3  and the upper opening  20  of the cover  2  may be omitted, with the middle cam portion  32  directly exposed to external allowing an external tool to operate therewith for moving the cover  2  in opposite directions. Moreover, the resilient beam  13  is not necessarily formed on the base  1 . Alternatively it may be formed on the cover  2 . The rotation direction of the cam  3  for rendering the cover  2  to move from open status to closed status is not limited to either clockwise or counter clockwise direction. Therefore, various modifications to the present invention can be made to the preferred embodiment by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.