Abstract:
A driving mechanism is used 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 portion rotatably retained in the first reception space of the cover and a lower portion rotatably and movably retained in the second reception space of the base. The upper portion of the driving cam is operative to rotate the lower portion of the driving cam in the second reception space which is subjected to reactive force from inner wall of the second reception space so that as the cam rotates it also moves linearly, thereby forcing the upper portion of the driving cam to pulling the cover to translate on the base.

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 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 driving a socket which comprises a cover movably mounted on a base. The driving mechanism comprises a first hole defined in the cover. A second hole is defined in the base and it has an upper opening in communication with the first hole and a lower opening in communication with the upper opening, wherein the upper opening is larger than the lower opening. A driving cam has an upper circular portion rotatably retained in a predetermined angular range in the first hole of the cover, a middle cam portion movably retained in the upper opening of the second hole of the base, and a lower cam portion movably retained in the lower opening of the second hole of the base. The cover is movable along a first direction with respect to the base when the upper circular portion of the driving cam is rotated clockwise while the cover is movable along a second direction opposite to the first direction when the upper circular portion of the driving cam is rotated counter-clockwise. 
     In accordance with one aspect of the present invention, a socket comprises a cover defining a first reception space. A base is movably engaged with the cover and defines a second reception space and a third reception space, wherein the second reception space is larger than the third reception space and it is communicated between the first reception space and the third reception space. A driving cam has an upper circular portion rotatably retained in a predetermined angular range in the first reception space, a middle cam portion rotatably and movably retained in the second reception space, and a lower cam portion rotatably and movably retained in the third reception space. The cover is translated along a first direction with respect to the base when the upper circular portion of the driving cam is rotated clockwise while the cover is translated along a second direction opposite to the first direction when the upper circular portion of the driving cam is rotated counter-clockwise. 
    
    
     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 and a portion thereof is shown by phantom line; 
     FIG. 2 is a schematic view of a cover of the connector of the invention taken from a bottom direction; 
     FIG. 3 is a perspective view of a driving cam in accordance with the present invention; 
     FIG. 4 is a perspective view showing the movable interconnection between the base, the driving cam, and a resilient beam of the cover; 
     FIG. 5 is a schematic view showing the movable interconnection between the base, the driving cam, and the resilient beam of the cover when the connector is in an open status; and 
     FIG. 6 is a schematic view showing the movable interconnection between the base, the driving cam, and the resilient beam of the cover when the connector is in a closed status. 
    
    
     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 . An upper hole  110  and a lower hole  120  communicating with the upper hole  110  are defined in the head  12 . The upper hole  110  is larger than the lower hole  120  and an inner circular flange  13  is formed around the lower hole  120 . A cutout  112  is defined in a periphery portion of the upper hole  110  as a gate therefore the upper hole  110  is assessable from a horizontal direction in addition to a vertical direction. Also referring to FIG. 1B, an upper stop  110 A and a lower stop  120 A are respectively formed in inner periphery of the upper hole  110  and the lower hole  120 . 
     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 . Two guiding arms  211  extend from opposite sides of the body portion  21  and each guiding arm  211  has two guiding recess  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 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 . A positioning hole  210  is defined in the head  22  of the cover  2  and it is in alignment with the upper hole  110  of the base  1 . A resilient beam  25  extends laterally from an inner wall of the cover  22  and includes an angled head  251  pointing to a lateral direction substantially parallel to a longitudinal axis of the cover  2 . 
     Referring to FIG. 3, a driving cam  3  comprises an upper circular portion  31 , for actuating the cover  2 , connected to a middle cam portion  32  connected to a lower cam 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 to rotate 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 circular portion  32  is sized to be rotatable received in the positioning hole  210  of the cover  2 . The middle cam portion  32  has a similar shape to the upper hole  110  of the base  1  and includes an upper protrusion  321  extending from a periphery thereof. A first groove  322  and a second groove  323  are defined in the periphery of the middle cam portion  32  and the two grooves  322 ,  323  are distanced from each other by substantially a sectional periphery of ninety degrees. The lower cam portion  33  has a lower protrusion  331  extending from a periphery thereof similar to the upper protrusion  321  formed in the middle cam portion  32 . 
     Referring to FIG. 4, the middle cam portion  32  and the lower cam portion  33  of the driving cam  3  are respectively received in the upper hole  110  and the lower hole  120  (see FIG. 1B) of the base  1 , with the middle cam portion  32  being rotatably and movably seated on the inner flange  13  (see FIG.  1 B). The circular portion  31  of the driving cam  3  is received in the positioning hole  210  of the cover  2 . However, for illustration purpose, most parts of the cover  2  are omitted herein with only the resilient beam  25  being shown. A periphery portion of the middle cam portion  32  exposes laterally through the cutout  112  of the base  2  to abut against the head  251  of the resilient beam  25  of the cover  2 . 
     The detailed operational relation between the driving cam  3 , the base  1  and the cover  2  are shown in FIGS. 5 and 6. Firstly referring to FIG. 5, the connector is in an open status, wherein the protrusion  321  of the middle cam portion  32  abuts against the upper stop  110 A of the upper hole  110  of the base  1  after the driving cam  3  has been rotated by the external tool clockwise to a first extreme. Simultaneously, the lower protrusion  331  of the lower cam portion  33  is distanced from the lower stop  120 A and the angled head  251  of the resilient beam is clicked into the first groove  322  of the middle cam portion  32 . The click caused by the angled head  251  and the first groove  322  of the middle cam portion  32  provides a user to have a good hand feeling that the connector has been operated in an open status. 
     Referring to FIG. 6, when the connector is operated from the open status to a closed status, the circular portion  31  is rotated counter-clockwise as shown by the arrow direction to a second extreme, and the protrusion  321  of the middle cam portion  32  is distanced from the upper stop  110 A until the lower protrusion  331  of the lower cam portion  33  abuts against the lower stop  120 A. Simultaneously, the angled head  251  of the resilient beam  25  is clicked into the second groove  323  of the middle cam portion  32 . It can be seen that the cover  2  is moved for a distance D along the longitudinal axis thereof when the connector is changed from the open status to the closed status. Similarly, the connector is operative to change from the closed status to the open status by rotating the circular portion  31  clockwise as shown by an arrow of FIG.  6 . 
     When the connector is operative from FIG. 5 to FIG. 6, the middle cam portion  32  is subjected to reactive force from inner wall of the upper hole  110  and performs rotation and movement thereby causing the circular portion  31  to drive the cover  2  to translate backward on the base  1 . Similarly, when the connector is operative from FIG. 6 to FIG. 5, the lower cam portion  33  is subjected to reactive force from inner wall of the lower hole  120  and performs rotation and movement thereby causing the circular portion  31  to drive the cover  2  to translate forward on the base  1 . 
     It should be noted that different from the traditional cam structure which has a camming surface rotating about a stationary pivot, the invention introduces a cam structure having the upper/lower hole  110 / 120  incorporating the middle/lower cam portion  32 / 33 , wherein the middle/lower cam portion  32 / 33  are not only rotatably but also linearly moved with the corresponding the upper/lower hole  110 / 120 . Under this situation, the upper circular portion  31  of the driving cam  3  may not only rotate but also move in a front-to-back direction, thus actuating the cover  2  to move in the front-to-back direction. 
     It is also noted that the middle cam portion  32  is generally of a circular form except that a gradually expansion section is formed with a ninety degrees range corresponding to the radius-increased dimension of the upper hole  110  about the first quadrant; similarly, the lower cam portion  33  is generally of a circular form except that a gradually expansion section is formed with a ninety degrees range corresponding to the radius-increased dimension of the lower hole  120  about the fourth quadrant. Therefore, through the engagement between the expansion section of the middle cam portion  32  and the upper hole  110 , the driving cam can move rearward with regard to the base  1 , while through the engagement between the expansion section of the lower cam portion  33 , the driving cam can move forward with regard to the base  1 . Understandably, the dimension of the upper hole  110  should be not only large enough to allow the middle cam portion  32  to rotate and linearly move in the front-to-back direction therein, but also small enough to allow the middle cam portion  32  to interact therewith for making a linear movement of the driving cam  3  with regard to the base  1  during rotation of the driving cam  3 . Similarly, the lower hole  120  also follows the same format. 
     It is further noted that because such two expansion sections are diametrically positioned on the driving cam  3 , such two expansions are preferably formed at two different levels as the invention for avoiding interference with the corresponding receiving hole if both two expansion sections are formed at the same level on the cam  3 . Additionally, the middle cam portion  32  of the driving cam  3  is relatively larger than the upper circular portion  31  and the lower cam portion  33  and the corresponding holes  110 ,  210  and  120  are defined in the similar manner accordingly, so as to reliably retain the driving cam  3  within the socket without up-and-down movement. 
     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.