Abstract:
A socket comprises a cover movably mounted on a base between an open status and a closed status. The cover and the base each have a body portion and a head portion extending from the body portion. The cover has first pair of inner walls and second pair of inner walls respectively formed in the body portion and the head portion thereof for slidably retaining the corresponding body portion and head portion of the base. Positioning members containing spaced shallow regions are formed in the body portion and the head portion of the base for receiving protrusions formed in the corresponding body portion and head portion of the cover so that the cover can be retained in either the open status or closed status by cooperation of the positioning members and the protrusions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a zero insertion force (ZIF) socket, and especially to a ZIF socket having a single-point driving mechanism which drives a cover of the socket to move smoothly 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 zero insertion force (ZIF) 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 socket having a cover movably engaged with a base and positioning means including a vertical protrusion on the side face of the base to cooperate with a pair of spaced shallow regions, named front shallow region and rear shallow region, formed in the interior portion of the cover. Therefore, the protrusion of the base may be received within the front shallow region in the cover when the socket is in an open status, and within the rear shallow region when the socket is in a closed status. However, the vertical protrusion on the side face of the base is apt to be worn out due to repeated friction with the inner wall of the shallow regions. If one of the vertical protrusions is worn out, the left one will cause an imbalance thus hindering the normal movement of the cover. 
     Moreover, a driving mechanism as disclosed in the prior art for driving the cover to move with respect to the base utilizes a screwdriver inserted into slots defined in the cover and the base to drive the cover. Since the slots are defined in expansion sections respectively extended from center portions of front sides of the base and the cover, the driving point is relatively small compared to the front side of the cover. With this structure, the driving force from the screwdriver is not guaranteed evenly distributed in two sides of the cover which may cause the cover to move not smoothly on the base. Additionally, when the user pivots the screwdriver he (she) needs a considerable space for operation and may be prohibited by peripheral components nearby thus causing difficulty. 
     It is requisite to provide a new socket to solve the above problems. 
     SUMMARY OF THE INVENTION 
     The primary purpose of the present invention is to provide an improved ZIF socket having a cover movably mounted on a base which has an even-force distribution structure for guaranteeing a cover to move smoothly on a base. 
     Another purpose of the present invention is to provide an improved ZIF socket having a driving cam simultaneously received in a base and a cover allowing a user to operate thereon with little space. 
     In accordance with one aspect of the present invention, a socket is provided to comprise a base and a cover movably mounted on the base. The base has a first body portion and a first head portion extending from the first body portion. The first body portion has a pair of wide spaced sides parallel to an axis of the base. The first head portion has a pair of narrow spaced sides parallel to the same axis of the base. At least one positioning member is formed in each pair of the wide spaced sides and the narrow spaced sides. The at least one positioning member has two shallow regions spaced by a rib. The cover has a second body portion and a second head portion extending from the second body portion. The second body portion has a pair of wide spaced inner walls movably receiving the pair of wide spaced sides of the base therebetween. The second head portion has a pair of narrow spaced inner walls movably receiving the narrow spaced sides of the base therebetween. At least one protrusion extends from each pair of the wide spaced inner walls and the narrow spaced inner walls for being positioned in one of the two shallow regions of the at least one positioning member of the base. 
     In accordance with another aspect of the present invention, a socket comprises a base, a cover movably mounted on the base, and a driving cam rotatably received in the base and the cover. The base has a first body portion and a first head portion extending from the first body portion along an axis thereof. A first reception space is formed in the first head portion and comprises two inner stop walls spaced from each other. At least one positioning member is formed in each of the first body portion and the first head portion, wherein the at least one position member comprises two shallow regions spaced by a rib. The cover has a second body portion and a second head portion extending from the second body portion. A second reception space is formed in the second head portion. At least one protrusion is formed in each of the second body portion and the second head portion, wherein the at least one protrusion is selectively positioned in one of the two shallow regions of the at least one positioning member of the base. The driving cam has a lower portion rotatably retained in the first reception space and rotatable between the two inner stop walls of the first reception space and an upper portion retained in the second reception space of the cover and rotatable to drive inner periphery portion of the cover thus moving the cover to move along the axis of the base. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a base of a ZIF socket connector in accordance with the present invention; 
     FIG. 2 is a perspective view of a cover of the connector in accordance with the present invention; 
     FIG. 3 is an enlarged view of a positioning member of the base; 
     FIG. 4A is perspective view of a driving cam used in the present invention; 
     FIG. 4B is perspective view of the driving cam of FIG. 3A taken from a different angle; 
     FIG. 4C is a top plan view of the driving cam; 
     FIG. 5 is a perspective view showing the driving cam is installed in the base; 
     FIGS. 6A to  6 C are operational schematic views of the driving cam with respect to the cover; 
     FIG. 7 is an enlarged schematic view of a positioning pair showing an open status between the cover and the base of the socket; 
     FIG. 8 is an enlarged schematic view of the positioning pair showing an closed status between the cover and the base of the socket; and 
     FIG. 9 is an assembled view of the socket in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a base  1  of a socket 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 parallel sides  11 A thereof and defines a plurality of passage ways  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 parallel sides  12 A thereof and a rib  161  extending from each groove  16 . The parallel sides  11 A of the head  12  and the parallel sides  12 A of the housing  12  are substantially parallel to a longitudinal axis  1 A of the base  1 . A pair of positioning members  18  are formed in the parallel sides  12 A of the head  12 . Similarly, another pair of positioning members  18  are formed in the parallel sides  11 A of the housing  11 . Also referring to FIG. 3, each positioning member  18  comprises two grooves  180  formed in the side wall  11 A (or  12 A) and spaced by a triangular rib  181 . A rear cutout  10  is defined in a rear side  11 B of the housing  11 . A reception cavity  110  is defined in the head  12 , with two inner stop walls  111  formed in an innerperiphery thereof. The inner stop walls  111  are substantially in the same side with respect to the longitudinal axis  1 A. 
     Referring to FIG. 2, 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 parallel inner walls  22 B 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 parallel opposite sides of the body portion  21  and each guiding arm  211  has two guiding recesses  25  formed in an inner wall  211 B thereof for slidably receiving the sliders  15  of the base  1  when the cover  2  is assembled to the base  1 . The inner surfaces  211 B of the guiding arms  211  are parallel to each other. A pair of triangular ribs  28  having substantially identical shape with the triangular rib  181  of the base  1  are formed in the inner walls  22 B of the head  22 . Similarly, another pair of triangular ribs  28  are formed in the inner surfaces  211 B of the housing  21 . A stopping bar  27  extends from a bottom surface of the body portion  21  substantially in alignment with rear side thereof for being received in the rear cutout  10  of the base  1  for limiting the moving 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 during movement thereof. 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 elliptic-like shape and the lower opening  220  has a rectangular-like shape. 
     Referring to FIGS. 4A to  4 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 or mark  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 an arcuate protrusion  333  extending from a periphery thereof with two abutment faces  334  on two sides of the protrusion  333 . 
     Referring to FIG. 5, 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 arcuate protrusion  333  is blocked by either of the inner stop walls  111  when it is rotated to one of two extremes of the 90-degree range. FIG. 5 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 stop walls  111  of the reception cavity  110  of the base  1 . 
     Referring to FIG. 9, 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  3  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  therewith. When the cover  2  is driven by the driving cam  3  to move on the base  1 , the upper opening  20  due to the elliptic-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. Moreover, the cover  2  may be smoothly moved on the base  1  because the head  22  and the body portion  21  thereof respectively movably retain the head  12  and the housing  11  of the base  1  and the driving cam  3  is located in the heads  12 ,  22  of the base  1  and the cover  2 . Specifically, the driving cam  3  can evenly move the two inner walls  22 B and the guiding arms  211  of the cover  2  from inner periphery of the lower opening  220  because the lower opening  220  is substantially formed in the axis of the head  22 . 
     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 . 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. 5) are rotated clockwise for substantially 90 degrees, thereby rendering the cover  2  to move along a first direction for a distance D. Similarly, the middle cam portion  32  can be rotated counter 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. 
     Referring to FIG. 7, the triangular rib  28  of the cover  2  is retained in one of the grooves  180  of the positioning member  18  when the cover  2  is remained in the open status. When the driving cam  3  is rotated in a first direction, the cover  2  is moved so that the rib  28  of the cover  2  is forced to slide over the rib  181  of the positioning member  18  of the base  1  and rest in the other groove  180  of the same positioning member  18  as shown in FIG.  8 . Similarly, the rib  28  of the cover  2  may be moved back to the original groove  180  as shown in FIG. 7, if the driving cam  3  is rotated in opposite direction. 
     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. 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.