Patent Publication Number: US-7909627-B2

Title: Multi-axis retention mechanism

Description:
The invention relates to electronic systems, and more particularly to novel connectors and retention mechanisms for add-in cards. 
     BACKGROUND AND RELATED ART 
     Many electronic systems provide the capability to supplement the functionality of the system by providing an interface through which additional electronic circuitry can be added to the system. For example, with reference to  FIG. 1 , a typical computer system  10  provides several connector slots  11  which are adapted to accept add-in cards  12 . The add-in cards  12  may be retained by the mechanical forces between the connector  11  on the system board  13  and the card edge connector  14  on the add-in card  12 . In many cases a bracket  15  is provided on the add-in card  12  which is secured to the chassis of the system at one end with a screw. 
     Some memory devices, which are relatively small, include latches on both ends of the memory connector. The latches help retain the memory card in the slot and may also be used to eject the memory card. 
     The power consumption and complexity of computer add-in cards has been increasing due to performance demands. For example, conventional high performance video cards may require power of about 25 watts and may weigh about 400 grams. As the required power increases, the weight of the add-in card consequently increases due to the need for more complex thermal solutions including larger heat sinks and fans. Even without increased power demands, the mass of the add-in card may increase due to larger card size and more devices and/or components on the add-in card. 
     If an add-in card is not sufficiently retained, the card can be displaced, or even dislodged from the system board connector, e.g. due to shock and vibration. This can result in an open circuit or even structural damage. The severity of the problem mainly depends on the card mass, the location of the center of gravity, and the card/connector design. Add-in cards with a large relative mass also have more inertia during shock and/or vibration events. The increased card inertia applies a larger impact force on constraining parts of the card such as the card connector. This can potentially cause failures such as the connector housing pulling off from soldered pins and/or other damage on the connector housing itself. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features of the invention will be apparent from the following description of preferred embodiments as illustrated in the accompanying drawings, in which like reference numerals generally refer to the same parts throughout the drawings. The drawings are not necessarily to scale, the emphasis instead being placed upon illustrating the principles of the invention. 
         FIG. 1  is a perspective view of a conventional electronic system. 
         FIG. 2  is a schematic view of a conventional system subject to a lateral force. 
         FIG. 3  is a perspective view of a retention mechanism according to some embodiments of the invention. 
         FIG. 4  is a perspective view of another retention mechanism according to some embodiments of the invention, with a latch member is an open position. 
         FIG. 5  is a perspective view of the retention mechanism from  FIG. 4 , with the latch member is a closed position. 
         FIG. 6  is a fragmented, perspective view of an electronic system utilizing the retention mechanism from  FIG. 4 . 
         FIG. 7  is another fragmented, perspective view of the electronic system from  FIG. 6 . 
         FIG. 8  is a perspective view of another retention mechanism according to some embodiments of the invention, with a latch member in an open position. 
         FIG. 9  is a perspective view of the retention mechanism from  FIG. 8 , with the latch member is a closed position. 
         FIG. 10  is a fragmented, perspective view of an electronic system utilizing the retention mechanism from  FIG. 8 . 
         FIG. 11  is another fragmented, perspective view of the electronic system from  FIG. 10 . 
         FIG. 12  is a perspective view of another retention mechanism according to some embodiments of the invention. 
         FIG. 13  is a fragmented, perspective view of an electronic system utilizing the retention mechanism from  FIG. 12 . 
         FIG. 14  is another fragmented, perspective view of the electronic system from  FIG. 3 . 
         FIGS. 15-18  are perspective views, from various viewpoints, of another retention mechanism according to some embodiments of the invention. 
         FIG. 19  is a fragmented, top schematic view of another electronic system utilizing the retention mechanism from  FIG. 15 . 
         FIG. 20  is a fragmented, side schematic view of the electronic system from  FIG. 19 . 
         FIG. 21  is a fragmented, perspective view of the electronic system from  FIG. 19 . 
     
    
    
     DESCRIPTION 
     In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, techniques, etc. in order to provide a thorough understanding of the various aspects of the invention. However, it will be apparent to those skilled in the art having the benefit of the present disclosure that the various aspects of the invention may be practiced in other examples that depart from these specific details. In certain instances, descriptions of well known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail. 
     As noted above, conventional high performance graphics cards may weigh about 400 grams or more. An add-in graphics card supporting the AGP standard may include a tab near the end of the connector to aid in retention of the card when the card is subject to vertical displacement forces. In general, to remove the card, a retention mechanism which engages with the tab must be manually disengaged. The supplemented retention is primarily in the vertical direction. An example of such a retention mechanism is described in U.S. Pat. No. 6,551,120, assigned in common with the present application. 
     The inventors have discovered that with heavier add-in cards (e.g. 400 grams or more), lateral forces on the card can unseat the card and/or cause damage to the system. For example, lateral forces (i.e. forces including a component which is transverse to the plane of the add-in card) may be generated when the electronic system is subject to an impact which is perpendicular to the orientation of the add-in card. With reference to  FIG. 2 , an electronic system  20  includes a system board  21  with a connector  22  mounted on the system board  21 . An add-in card  23  is attached to the connector  22  and overhangs the connector  22  on both ends. The add-in card  23  may include a bracket  24  on one end which may be attached to a chassis of the system  20 . When a lateral force F is applied to the card  23 , an end  25  of the card (opposite of the bracketed end) may flex, as indicated by the curved arrows A and B. Under lateral forces, a point P near the end of the connector  22  essentially becomes a pivot point about which the flexible material of the card  23  can bend. With a sufficiently heavy card subject to a sufficiently heavy lateral force, the flexing end  25  of the card can torque the card  23  out of the connector  22  and/or cause damage to the card  23 , connector  22  and/or system  20 . 
     The inventors have performed extensive tests for heavier cards in a computer system to confirm that card retention failure during shock and vibration conditions may occur due to impacts made perpendicular to the card. Even advanced graphics cards with the additional retention tab fail the tests. It is believed that the conventional supplemental retention tab has limited effect on restricting card deflection during side impact and therefore is not satisfactory to solve the side impact failures. In some instances (e.g. with a 400 gram graphics card), the additional retention tab was broken during shock testing. 
     Various retention mechanisms providing a side constraint are disclosed in U.S. patent application Ser. No. 10/404,975, filed Mar. 31, 2003, entitled RETENTION MECHANISM FOR HIGH MASS ADD-IN CARDS, assigned in common with the present application. 
     With reference to  FIG. 3 , an example retention mechanism  30 , according to some embodiments of the invention, provides constraints in multiple axes. For example, the retention mechanism includes a connector  32  and a guide  34 . The connector  32  and the guide  34  may be integral or may be separate assemblies. The guide  34  includes spaced apart and opposed side walls  34   a  and  34   b , which define a relatively tall slot  36 . The walls  34   a  and  34   b  are adapted to contact a card inserted in the slot  36  and inhibit lateral movement of the card. For example, the guide  34  contacts one or more side surfaces of the card to reduce the amount the card may flex about the pivot point near the end of the connector  32 . Preferably, the guide  34  is adapted to provide a side constraint which substantially prevents lateral flexing of the card at the point where the guide  34  contacts the card. In addition, the guide  34  includes a latch  37  which is adapted to interface with a structure on the card to inhibit vertical movement of the card. For example, the card may include an opening (e.g. a slot or a tab) which is positioned in the slot  36  when the card is seated in the connector  32 . The latch  37  is operable to pivot about a pivot point  37   a  and includes a protrusion  38  which is adapted to engage the opening, thereby inhibiting removal of the card without disengaging the latch  37 . The latch  37  may include a contact surface  39  for a user to contact when opening and/or closing the latch. In some embodiments, the latch  37  is installed in the body of the guide  44  and pivots perpendicularly to the length of the connector  42 . In the illustrated example, the latch  37  is oriented transverse, and preferably perpendicular, to the side walls  34   a  and  34   b  (e.g. the pivot axis is parallel to the lengthwise axis of the connector). Thus, in some embodiments, the retention mechanism  30  inhibits both lateral and vertical movement of the card. With the additional constraint provided by the connector  42  in the X-axis, the card is effectively constrained in all three axes (e.g. lengthwise axis of connector corresponds to the X-axis, lateral movement corresponds to the Y-axis, and vertical movement corresponds to the Z-axis). 
     An appropriate guide for a particular electronic system may take any suitable form and may be made from any suitable material. Plastic is a preferred material for the guide. Preferably, the guide provides a slot or channel that is a close fit with the thickness of the add-in card. For example, the guide may define a slot between two resilient protrusions (e.g. walls  34   a  and  34   b ). The width of the slot may be less than the thickness of the card, with the protrusions being sufficiently resilient to expand to accept the card. An advantage of the resilient protrusions is that they provide retention forces in the both the vertical and lateral directions, thus supplementing the retention force provided by the latch and the retention tab. 
     With reference to  FIGS. 4-5 , another retention mechanism  40  includes a guide  44 . In some embodiments the guide  44  may be made integral with a connector (not shown). The guide  44  includes spaced apart and opposed side walls  44   a  and  44   b , which define a relatively shallow slot  46 . The guide  44  further includes a latch  47  which is adapted to pivot about a pivot point  47   a  from an open position (see  FIG. 4 ) to a closed position (see  FIG. 5 ). The latch  47  includes a ribbed contact surface  49 . In some embodiments, the latch  47  includes a protrusion  48  which may be offset to one side with respect to an arm  51  of the latch  47 . 
     As compared to the embodiment of  FIG. 3 , the embodiment of  FIG. 4  provides a relatively shorter slot. Depending on the requirements of the application, slots of varying height may be provided. For example, a deep slot may be more effective in supporting the card during a Y-axis shock, but requires more clearance area (e.g. keepout) on the card. Conversely, for some applications, a shorter slot may provide sufficient lateral constraint while reducing the keepout impact to the card. 
     With reference to  FIGS. 6 and 7 , an electronic system  60  according to some embodiments of the invention includes a system board  61  and a connector  42  mounted on the system board  61 . An electronic card  63  is attached to the connector  42  and overhangs the connector  42  (e.g. at least on an inward end of the card  63  with respect to an outer wall of the system chassis). The system  60  further includes the guide  44  secured to the system board  61 , where the guide  44  is adapted to inhibit lateral movement of the card  63 . In some embodiments, the guide  44  may be spaced from the connector  42 . In some embodiments, the guide  44  may abut the connector  42 . In some embodiments, the guide  44  may be integral with the connector  42 . 
     For example, the walls  44   a  and  44   b  of the guide  44  may contact one or more side surfaces of the card  63  to reduce the amount the card  63  may flex about the pivot point near the end of the connector  42 . Preferably, the guide  44  is adapted to provide a side constraint which substantially prevents lateral flexing of the card  63  at the point where the guide  44  contacts the card  63 . With the latch  47  in an open position, the guide  44  allows the card  63  to be inserted into the connector  42 . The card  63  includes an extension (e.g. a retention tab)  65  which is positioned in the slot  46  when the card  63  is seated in the connector  42 . The latch  47  may them be moved to a closed position. With the latch  47  in the closed position, a surface of the protrusion  48  engages a surface  67  of the tab  65  to inhibit removal of the card  63  or other Z-axis movement of the card  63  out of the connector  42 . 
     In some embodiments, the latch  47  may include a lever design that combines card insertion, retention, and ejection functions. An example of such a multi-function lever design is described in U.S. Patent Publication No. 2003/0137811 A1. For example, the latch  47  may include a base portion between the pivot axis (e.g. about pivot point  47   a ) and the bottom of the guide  44 . The base portion may include a protrusion. When the card is positioned in the slot  46 , the bottom of the tab  65  (or another portion of the card  63 ) may contact the protrusion. When the card  63  is pushed into the connector  42 , the tab  65  pushes the protrusion and causes the latch  47  to automatically go from the open position to the closed position. Alternatively, the latch  47  may be manually moved from the open position to the closed position to assist in the insertion of the card  63  in the connector  42  (with the protrusion  48  applying an insertion force on the surface  67  of the tab  65 ). During removal, the latch  47  may be moved from the closed position to the open position to assist in the removal of the card  63  from the connector  42 . Specifically, the protrusion on the base portion of the latch  47  contacts a bottom edge of the card  63  and applies a positive vertical removal force which assists in removing the card  63  from the connector  42 . 
     Advantageously, some embodiments of the invention may include a combination of features relating to inhibiting lateral card movement, inhibiting vertical card movement, and providing improved functions for at least one of the card insertion or ejection operations. The numerous possible configurations of the retention mechanisms described herein provide design flexibility, scalability, and have only minor impact on the system board layout. 
     Any suitable technique may be utilized to secure the guide  44  to the system board  61 . For example, the guide  44  may define one or more openings adapted to receive a fastener (e.g. a screw). The system board  61  may provide corresponding mounting holes (not shown). In some embodiments, the system board  61  corresponds to an ATX compatible motherboard. In some embodiments, the guide  44  may be secured to an ATX mounting hole already provided on the motherboard, thus reducing the amount of rework or board re-routing required to utilize the guide  44 . 
     In some embodiments, the guide  44  may include alignment features to aid in the positioning of the slot  36  with respect to the connector  42 . For example, a guide may define a plurality (i.e. at least two) of holes which are used as alignment features. Corresponding mounting holes are provided on the system board. The holes may be keyed. The mounting holes may be configured such that when the holes in the guide are aligned with the mounting holes, the slot defined by the guide is aligned with the lengthwise axis of the connector. For example, the guide may be mounted on the system board via two wave-soldered through-hole pins. Other methods of board mounting can also be used such as press-fit, or the addition of snap-in features. Many other variations of the guide and mounting fasteners are possible. 
     With reference to  FIGS. 8-9 , another retention mechanism  80  includes a guide  84 . In some embodiments the guide  84  may be made integral with a connector (not shown). The guide  84  includes spaced apart and opposed side walls  84   a  and  84   b , which define a slot therebetween The one wall  84   a  is relatively taller than the other opposed wall  84   b . The guide  84  further includes a latch  87  which is adapted to pivot about a pivot point  87   a  from an open position (see  FIG. 8 ) to a closed position (see  FIG. 9 ). The latch  87  includes a ribbed contact surface  89 . In some embodiments, the latch  87  includes a protrusion  88  which may be offset to one side with respect to an arm  91  of the latch  87 . 
     As compared to the embodiment of  FIG. 4 , the embodiment of  FIG. 8  provides a wider contact surface  89 , which in some applications may improve the operability. Also, the protrusion  88  is provided with a relatively longer offset from the arm  91 , which may increase the leverage during insertion and retention. The guide  84  also provides a relatively taller wall  84   a  on one side of the slot. Having a taller wall on only one side may improve the lateral stability while reducing the impact on the clearance area required for the card. 
     With reference to  FIGS. 10 and 11 , an electronic system  100  according to some embodiments of the invention includes a system board  101  and a connector  82  mounted on the system board  101 . An electronic card  103  is inserted into the connector  82  and overhangs the connector  82  (e.g. at least on an inward end of the card  103  with respect to an outer wall of the system chassis). The system  100  further includes the guide  84  secured to the system board  101 , where the guide  84  is adapted to inhibit lateral movement of the card  103 . In some embodiments, the guide  84  may be spaced from the connector  82 . In some embodiments, the guide  84  may abut the connector  82 . In some embodiments, the guide  84  may be integral with the connector  82 . 
     With reference to  FIG. 12 , another retention mechanism according to some embodiments of the invention provides a one piece guide with an integral latch. A retention mechanism  120  includes a guide  124  having spaced apart walls  124   a  and  124   b  defining a slot  126  therebetween. A resilient arm  125  extends parallel to the slot  126  from the wall  124   a  (although some embodiments may include a resilient arm along wall  124   b ). The arm  125  includes a protrusion  128  which extends inward toward the slot  126 . At an end of the arm  125 , distal to the guide  124 , the arm includes a contact surface  129  for contact by a user. The protrusion  128  is adapted to cooperate with a corresponding feature in an add-in card, to inhibit removal of the card. The arm  125  may be vertically positioned at any suitable location along the wall  124   a , although in some embodiments positioning the arm  125  near the top of the wall  124   a  may be preferred. 
     With reference to  FIGS. 13 and 14 , an electronic system  130  according to some embodiments of the invention includes a system board  131  and a connector  122  mounted on the system board  131 . An electronic card  133  is attached to the connector  122  and overhangs the connector  122  (e.g. at least on an inward end of the card  133  with respect to an outer wall of the system chassis). The system  130  further includes the guide  124  secured to the system board  131 , where the guide  124  is adapted to inhibit lateral movement of the card  133 . In some embodiments, the guide  124  may be spaced from the connector  122 . In some embodiments, the guide  124  may abut the connector  122 . In some embodiments, the guide  124  may be integral with the connector  122 . 
     For example, the walls  124   a  and  124   b  of the guide  124  may contact one or more side surfaces of the card  133  to reduce the amount the card  133  may flex about the pivot point near the end of the connector  122 . Preferably, the guide  124  is adapted to provide a side constraint which substantially prevents lateral flexing of the card  133  at the point where the guide  124  contacts the card  133 . The card  133  includes an extension (e.g. a retention tab)  135  which is positioned outside the slot  126  when the card  133  is seated in the connector  122 . A surface of the protrusion  128  engages a surface  137  of the tab  135  to inhibit removal of the card  133  or other Z-axis movement of the card  133  out of the connector  122 . 
     When inserting the card  133 , the user may contact the contact surface  129  of the arm  125  to move the protrusion out of the way for card insertion. Preferably, the protrusion  128  includes an angles surface  127  which reduces the need for the user to move the protrusion  128  out of the way during card insertion. During insertion, an edge of the tab  135  contacts the angled surface  127  and deflects the resilient arm  125 . When the card  133  is seated, the tab  135  is clear of the protrusion  128  and the protrusion  128  snaps into place to aid in the retention of the card  133 . To remove the card  133 , the arm  125  is bent out of the way and the card  133  may be pulled out of the connector  122  without substantial impediment from the protrusion  128 . Another surface (e.g. the surface adjacent to surface  127 ) of the protrusion  128  may also be beveled to allow for less deflection of the arm  125  during removal of the card  133 . 
     With reference to  FIGS. 15-18 , another retention mechanism according to some embodiments of the invention provides a one piece guide with an integral latch. A retention mechanism  150  includes a guide  154  having spaced apart walls  154   a  and  154   b  defining a slot  156  therebetween. A resilient arm  155  extends parallel to the slot  156  from the wall  154   a  (although some embodiments may include a resilient arm along wall  154   b ). The arm  155  includes a protrusion  158  which extends inward toward the slot  156 . At the end of the cantilevered arm  155 , distal to the guide  154 , the arm includes a ribbed contact surface  159  for contact by a user. The protrusion  158  is adapted to cooperate with a corresponding feature in an add-in card, to inhibit removal of the card. The arm  155  may be vertically positioned at any suitable location along the wall  154   a , although in some embodiments positioning the arm  155  near the top of the wall  154   a  may be preferred. 
     With reference to  FIGS. 19-21 , an electronic system  190  according to some embodiments of the invention includes a system board  191  and a connector  152  mounted on the system board  191 . An electronic card  193  is attached to the connector  152  and overhangs the connector  152  (e.g. at least on an inward end of the card  193  with respect to an outer wall of the system chassis). The system  190  further includes the guide  154  secured to the system board  191 , where the guide  154  is adapted to inhibit lateral movement of the card  193 . In some embodiments, the guide  154  may be spaced from the connector  152 . In some embodiments, the guide  154  may abut the connector  152 . In some embodiments, the guide  154  may be integral with the connector  152 . 
     For example, the walls  154   a  and  154   b  of the guide  154  may contact one or more side surfaces of the card  193  to reduce the amount the card  193  may flex about the pivot point near the end of the connector  152 . Preferably, the guide  154  is adapted to provide a side constraint which substantially prevents lateral flexing of the card  193  at the point where the guide  154  contacts the card  193 . The card  193  includes an extension (e.g. a retention tab) which is positioned outside the slot  156  when the card  193  is seated in the connector  152 . A surface of the protrusion  158  engages a surface of the tab to inhibit removal of the card  193  or other Z-axis movement of the card  193  out of the connector  152 . 
     When inserting the card  193 , the user may contact the contact surface  159  of the arm  155  to move the protrusion out of the way for card insertion. Preferably, the protrusion  158  includes an angles surface  157  (see  FIG. 15 ) which reduces the need for the user to move the protrusion  158  out of the way during card insertion. During insertion, an edge of the tab  195  contacts the angled surface  157  and deflects the resilient arm  155 . When the card  193  is seated, the tab  195  is clear of the protrusion  158  and the protrusion  158  snaps into place to aid in the retention of the card  193 . To remove the card  193 , the arm  155  is bent out of the way and the card  193  may be pulled out of the connector  152  without substantial impediment from the protrusion  158 . Another surface (e.g. the surface adjacent to surface  157 ) of the protrusion  158  may also be beveled to allow for less deflection of the arm  155  during removal of the card  193 . 
     As compared to the retention mechanism of  FIG. 12 , the distance between the arm  155  and the board  191  varies along the length of the arm  155 , preferably with the distance increasing along the length. The system  190  may include an optional component  199  (e.g. a capacitor or other electronics device) mounted on the system board and positioned between the arm  155  and the system board  191 . Advantageously, the greater distance between the board  191  and the arm  155  allows a taller component to be positioned under the arm  155 . 
     A method according to some embodiments includes providing a system board, mounting a connector on the system board, attaching an electronic card to the connector, the card overhanging the connector at least on an inward end of the card; and securing a guide to the system board spaced from the connector, providing a latch connected to the guide, inhibiting lateral movement of the card with the guide; and inhibiting removal of the electronic card from the connector with the latch. 
     The foregoing and other aspects of the invention are achieved individually and in combination. The invention should not be construed as requiring two or more of such aspects unless expressly required by a particular claim. Moreover, while the invention has been described in connection with what is presently considered to be the preferred examples, it is to be understood that the invention is not limited to the disclosed examples, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and the scope of the invention.