Abstract:
An enclosure and method of making the same provides mounting provisions for shields of expansion cards in a general purpose computer that reduce the number of components and manufacturing steps to produce the enclosure, as well as reducing the time required to add or remove expansion cards. In particular, a housing of an enclosure incorporates a shield mount to receive a shield having an extending tongue and a lateral tab. A specific example of such a shield is tail stock for a Peripheral Component Interconnection (PCI) expansion card. In particular, a receptor is formed into the housing for receiving the extending tongue of the shield. A support member extends outward from the enclosure to abut an outwardly bent tab of the shield that projects out of the panel through a tab opening adjacent to the support member. The support member includes a locking detent that fits within a locking recess in the tab of the shield. A cover of the enclosure mounts to the housing and includes a cover projection that abuts the tab of the shield from a disengagement direction, cooperating with the support member to lock the tab of the shield in place when the cover is installed.

Description:
FIELD OF THE INVENTION 
     The invention is generally related to expansion card mounting provisions in a computer enclosure, and in particular to Peripheral Component Interconnection (PCI) circuit board shield attachments to a housing of a computer enclosure. 
     BACKGROUND OF THE INVENTION 
     General purpose computers are widely used in homes and businesses to perform many functions. Adapting general purpose computers to perform these varied functions is supported by a flexible architecture. Users may select among a variety of user interface peripheral devices, communication devices, and mass storage devices to configure a general purpose computer for a specific application. 
     An enclosure for general purpose computers, also referred to as computer chassis or case, supports a flexible computer architecture with provisions for internally mounting various devices such as circuit boards and disk drives. An enclosure also includes provisions for connecting to peripheral devices outside of the enclosure. Examples of such connections include parallel and serial ports. 
     The Peripheral Component Interconnect (PCI) standard is an example of an expansion card approach to support both objectives of supporting internal components and communicating with external devices. Expansion card slots within an enclosure provide space for additional circuit boards as well as electrical interconnections to other components within the enclosure, such as a parallel data bus to a motherboard. Each expansion card slot may have access to the exterior of the enclosure via an expansion slot opening in the enclosure for interconnections to peripheral devices. A PCI shield, or tail stock, registers over the expansion slot opening, making substantial electrical contact to the enclosure to provide Electromagnetic Compatibility (EMC), reducing radio frequency (RF) emissions from or into the enclosure via the expansion slot opening. The PCI shield also prevents cooling air flow from being inadvertently diverted and causing overheating within portions of the enclosure. In addition, the enclosure includes mountings for each PCI shield to physically secure the PCI shield in place, and any circuit board attached to the shield. 
     Mounting provisions for PCI shields are conventionally made with a large rectangular hole in the enclosure across which a PCI bracket is welded. A PCI bracket is typically capable of retaining multiple PCI shields. The PCI bracket conforms to the shape of PCI shields with physical retention provided by a combination of guides into which tongues defined at the ends of each of the multiple PCI shields may be slid to orient the PCI shields in a generally parallel relationship. Fasteners such as screws, flip latch mechanisms or clips are typically used to secure lateral tabs at the opposite ends of the PCI shields and thereby secure the shields within the PCI bracket. A PCI shield with no card attached (blanking cover) is used to close openings when no expansion card is needed. 
     Conventional PCI mounting provisions do secure the PCI shield, provide EMC features, and close the expansion slot opening to the expansion card slot. However, the requirement for a PCI bracket adds another component to the enclosure, as well as another manufacturing step to weld the PCI bracket to the enclosure. Similarly, the fastener for each expansion card slot increases the time required to assemble a general purpose computer or to perform upgrades and maintenance. Therefore, a significant need exists for an improved enclosure for a general purpose computer for mounting PCI expansion cards. 
     SUMMARY OF THE INVENTION 
     The invention addresses these and other problems associated with the prior art by providing an enclosure and method of making the same in which a housing and a cover are used to cooperatively retain an expansion card shield within the enclosure. In particular, an enclosure includes a housing with a receptor and a tab opening. The tab of the shield is allowed to extend through the tab opening when the shield is placed within the enclosure in a disengaged position. The tab opening is sized to allow the shield to be moved longitudinally to an engaged position wherein a tongue of the shield engages the receptor. The cover then retains the shield in the engaged position by restricting movement of the tab of the shield when the cover is secured to the enclosure. 
     In another aspect consistent with the invention, a method of making an enclosure for receiving a shield includes defining an expansion card shield mounting sized for the tongue of the shield. A tab opening in the panel is formed at a first end of the expansion card shield mounting, with the tab opening laterally sized to receive the tab of the shield with the tongue of the shield proximate to and aligned with the expansion card shield mounting. The tab opening is longitudinally sized to allow displacement of the tab along the longitudinal axis of the expansion card shield mounting between a disengaged position and an engaged position. A receptor is formed at a second end of the expansion card shield mounting longitudinally displaced from the tab opening sufficient to clear the tongue of the shield when the tab is inserted through the tab opening at the disengaged position and to engage the tongue of the shield when the tab is translated to the engaged position. 
     These and other advantages and features, which characterize the invention, are set forth in the claims annexed hereto and forming a further part hereof. However, for a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the Drawings, and to the accompanying descriptive matter, in which there are described exemplary embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective exploded view of a computer enclosure for use in retaining an expansion card in a manner consistent with the invention. 
     FIG. 2 is a perspective view of the enclosure of FIG. 1 with the shield of an expansion card aligned for insertion into a shield mount in the enclosure. 
     FIG. 3 is a perspective view of the enclosure of FIG. 1, with the shield of the expansion card inserted into the shield mount and positioned in a disengaged position. 
     FIG. 4 is a perspective view of the enclosure of FIG. 1, with the shield of the expansion card inserted into the shield mount to an engaged position, and with a cover of the enclosure shown in proximity thereto. 
     FIG. 5 is a perspective view of the enclosure of FIG. 1, with the shield of the expansion card retained in the engaged position by installation of the cover onto the housing. 
     FIG. 6 is a cross sectional view of the enclosure of FIG. 5 taken along lines  6 — 6 . 
     FIG. 7 is a perspective view of a tailgate of another computer enclosure consistent with the invention including two stacked shield mounts tangentially retained by a cover. 
     FIG. 8 is a side view of a tailgate of another computer enclosure consistent with the invention having a plurality of shield mounts perpendicularly retained by a cover. 
    
    
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
     DETAILED DESCRIPTION 
     For purposes of this description, words such as “inward”, “outward”, “front”, “rear”, “up”, “right”, “left”, “down”, and the like are applied in conjunction with the drawings for purposes of clarity. As is well known, enclosures may be oriented in substantially any orientation, so these directional words should not be used to imply any particular absolute directions for an enclosure consistent with the invention. 
     FIG. 1 is a perspective exploded view of a panel, such as a tailgate  10 , of a computer enclosure  12  having horizontally aligned shield mounts  14 ,  15  behind which may be placed computer expansion cards in expansion card slots  16 ,  17 . The tailgate  10  is a rear portion of a housing  18 . The housing  18  substantially encompasses and supports electronic components. The enclosure  12  also includes a cover  20  that mounts to the housing  18 . 
     An example of an expansion card suitable for use in enclosure  10  is a Peripheral Component Interconnect (PCI) circuit board  22  that includes an Electromagnetic Compatibility (EMC) shield  24  along one edge for being positioned against the inside of the tailgate  10 . The shield  24  provides structural mounting features for the expansion card  22 . Additionally, the shield  24  often includes a connector (not shown in FIG. 1) that is intended to extend outside of the computer enclosure  12 . Typically, the shield  24  is made of stamped sheet steel, providing the desired structural strength as well as serving as an EMC barrier for a connector opening, or more generally an expansion slot opening  26 , in the computer enclosure  12 . 
     FIG. 2 is a perspective view of the shield  24  of the PCI circuit board  22  of FIG. 1 aligned for insertion into the shield mount  14  of tailgate  10 . The shield  24  is depicted with features commonly included in PCI circuit boards  22 . Connectors  28 ,  30 ,  32  are externally facing on an extending tongue  34  of the shield  24 . Opening  26  in the tailgate  10  is sized to allow external access to the connectors  28 ,  30 ,  32  and to be substantially covered by the extending tongue  34  of the shield  24 . The shield  24  also includes a laterally extending tab  36 , which is generally perpendicularly bent for the illustrative stamped steel PCI shield  24 . The lateral tab  36  includes a locking recess  38  through which it is known in other applications to insert a screw into a PCI bracket to hold the shield  24  against a tailgate after inserting the extending tongue  34  into a PCI bracket. 
     It should be appreciated that in some applications an expansion slot opening  26  is not required or desired and may be omitted. In such applications, a shield  24  consistent with aspects of the invention provides structural support to an expansion card and need not provide EMC and connector features. In addition, other circuit boards and devices may advantageously use a shield  24  consistent with aspects of the invention that are intended for permanent installation in an enclosure, rather than an upgrade in an expansion slot. Furthermore, a shield  24  without any attached circuit board  22  may be advantageously used to close an expansion slot opening  26 . In addition, a shield  24  consistent with aspects of the invention may comprise various geometries of an extending tongue  34  and a tab  36 . 
     The shield mount  14  is advantageously formed from sheet material by machining or stamping out the expansion slot opening  26 . Also, a contour for a receptor  40  is stamped as a lateral band  41  across the shield mount  14  that is inwardly displaced from a plane of the tailgate  10  to receive a narrow end  42  of the extending tongue  34 . Generally, the inward displacement of the receptor  40  narrows to approximately the cross section of the extending tongue  34  of the shield  24 , providing a structural support in each direction, except in a disengaging direction, as at arrow  43 , where the receptor  40  generally only provides frictional resistance. To guide the narrow end  42  of the tongue  34  into the lateral band  41 , the receptor  40  includes a ramp  44  along a side in the disengaging direction  43  that is further inwardly deflected. 
     In certain applications, receptors  40  consistent with aspects of the invention may include a plurality of discrete components that cooperatively guide and restrict the tongue  34  of the shield  24 . Thus, a guide pin or a channel, open toward the shield mount  14  may receive or restrict one of the narrow edge of the end  42  or a lateral edge of the tongue  34 . 
     A contour for a support member  45  is stamped and outwardly bent from the plane of the tailgate  10 , in a hinged movement about an edge toward an engaging direction, as in arrow  46 , along a longitudinal axis of the shield mount  14 . The support member  45  includes a recess  47  integrated with the expansion slot opening  26  to accommodate any outwardly projecting connector (not shown) near the tab  36  on the shield  24 . A tab opening  48  is formed adjacent to the support member  45 , opposite to the expansion slot opening  26 . The tab opening  48  is advantageously formed when the support member  45  is stamped out of the sheet material of the tailgate  10 . 
     The generally rectangularly shaped tab opening  48  is laterally sized to receive the tab  36  in the disengaged position, wherein the tongue  34  of the shield  24  is placed against or proximate to the inside surface of the tailgate  10 . The tab opening  48  is longitudinally sized and positioned with respect to the receptor  40  to allow the tab  36  to be received sufficiently in the disengaging direction  43  so that the tongue  34  is not impeded by the receptor  40 . Moreover, the tab opening  48  allows longitudinal displacement of the tab  36  in the engaging direction  46  so that the tongue  34  engages the receptor  40 . 
     The support member  45  also may include a locking detent  50  that registers to the locking recess  38  of the tab  36 . The locking detent  50  is advantageously stamped and bent from the sheet material of the tailgate  10 , although other geometries and manufacturing methods may be used in the alternative. 
     It should be appreciated that the fabrication of a shield mount  14  entirely from a single sheet of material such as sheet steel reduces manufacturing costs. However, in some applications consistent with aspects of the invention, the various features of shield mount  14  may be provided as separate components, and that the slot may be molded from alternate materials and otherwise assembled in various other manners known to those skilled in the art having the benefit of the present disclosure. Furthermore, in some applications consistent with the invention, the support member  45  may be omitted with the shield  24  held securely in place by the cooperation between the tab opening  48 , cover  20  and receptor  40 . 
     FIG. 3 is a perspective view of the shield  24  of the PCI circuit board  22  of FIG. 2 inserted into the shield mount  14  in a disengaged position wherein the tab  36  is longitudinally displaced in the disengaging direction  43 , with respect to the receptor  40 . The disengaging direction  43  is opposite to the engaging direction  46  and is generally along the longitudinal axis of the shield  24 . In the disengaged position, the extending tongue  24  contacts the inside of the tailgate  10  with tab  36  projecting outward through the tab opening  48 . In the disengaged position, the receptor  40  does not substantially interfere or impede with the narrow end  42  of the shield  24 . 
     FIG. 4 is a perspective view of the shield  24  of FIG. 3 inserted into the shield mount  14  in an engaged position. The narrow end  42  is fully engaged within the receptor  40 . The support member  45  prevents any further movement of the shield  24  in the engaging direction  46  beyond the engaged position. The locking detent  50  fits within the locking recess  38  when the shield  24  is in the engaged position, preventing inward pivoting of the shield about its narrow end  42 . 
     A computer motherboard (not shown) generally provides electrical interconnection to the other components in the enclosure  12  as well as additional physical support to the circuit board  22 . An edge connector on the mother board is aligned to receive an edge connection along a side of the circuit board  22  perpendicular to the shield  24  when the shield  24  in the disengaged position. This edge connection side of the circuit board  22  is adjacent to the extending tongue  34  of the shield  24 . Furthermore, the edge connector of the motherboard is configured to be engaged to the edge connection of the circuit board  22  when the shield  24  is in the engaged position. 
     Referring to FIGS. 4 and 5, a cover  20  includes features for secure mounting to the housing  18 . The cover  20  provides a shield retainer  51  to cooperate with the tab opening  48 , and advantageously the support member  45 , to block the tab  36  in the engaged position. In particular, an inwardly opening cover curl  52  receives an outwardly bent lip  54  along the top edge of the tailgate  10 . The curl  52  includes a tab cutout  56  to accommodate the tab  36  of the shield  24 . A cover projection  58  extends from a portion of the curl  52  and registers at least to the tab opening  48  in the tailgate  10 . The cover projection  58  also includes an outwardly projecting surface  59  registered to oppose the tab  36  from moving in the disengaging direction  43 . Since the illustrative version of the enclosure  18  has a horizontally aligned shield mount  14 , the tab  36  is tangentially aligned to the cover projection  58  during mounting of the cover  20 . 
     The cover projection  58  advantageously includes a fastener attachment, such as a thumb screw  60 , for fastening the cover  20  to the housing  18  without tools. Other fastener attachments, installed with or without assistance of a tool, may be used, such as a metal screw, wing nut, prop rivet. In some application consistent with aspects of the invention, the cover projection  58  may have no fastener attachment. 
     FIG. 6 is a cross sectional view of the installed shield  24  of FIG. 5, generally along lines  6 - 6 , illustrating how a shield  24  is received within the receptor  40  and tab opening  48  and retained in place by the cover  20 . In particular, the tongue  34  is aligned in parallel to the plane of the tailgate  10 , and outwardly moved, as at arrow  61 , to be in contact with, or at least proximate to, an inner surface of the tailgate  10 . The shield  24  may not move further in the outward direction  61 . The tab  36  is thereafter displaced in the engaging direction  46  until proximate to or in contact with the support member  45 . Meanwhile, the narrow end  42  of the tongue  34  enters a space defined between the ramp  44  and the tailgate  10  and is guided into a narrow space between the lateral band  41  of the receptor and the tailgate  10 . Once in the engaged position, the locking detent  50  of the support member  45  engages the locking recess  38  of the tab  36 , preventing movement of the tab  36  transverse to the plane of the tailgate  10 . In addition, the surface  59  of the cover projection  58  prevents movement of the tab  36 , and thus the shield  24 , in the disengaging direction  43 . 
     FIG. 7 is a perspective view of another design of tailgate  62  on a computer enclosure  64 , including two stacked shield mounts  66 ,  68  tangentially retained by a single cover projection  70  that is tangentially proximate or in abutment to both tabs  72 ,  74 . 
     FIG. 8 is a side view of another design of tailgate  76  of a computer enclosure  78  having a plurality of shield mounts  80 ,  82 ,  84  perpendicularly retained by a cover  86 . 
     These various orientations of shield mounts  14 ,  16 ,  80 ,  82 ,  84  benefit from a shield retainer  51  incorporated into the respective cover  20 ,  86 . Thus, covers  20 ,  86  consistent with aspects of the invention incorporate various shield retainers  51 , such as one or more cover projections  58 , with each cover projection  58  retaining one or more shields  24  in the engaged position. In addition, a cover  20  consistent with aspects of the invention may have no cover projection  58 , especially for vertically oriented shield mounts  80 ,  82 ,  84  wherein the engaged position is defined with the tabs  36  of the shields  24  flush with the top of the tailgate  76  (not shown). Thus, the tab openings  48  would provide the longitudinal movement of the thickness of the tabs  36  to achieve this flush configuration and the adjacent portion of the cover  20  acts as the shield retainer  51 . 
     In use, an enclosure  12  is opened to insert a circuit board  22  by removing a cover  20  from a housing  18 . The housing includes a panel, or tailgate  10 , that has shield mount  14  to receive the shield  24  attached to the circuit board  22 . The tab  36  of the shield  24  is inserted through a tab opening  48  in the tailgate  10  with the extending tongue  34  of the shield  24  approximately adjacent to the inner surface of the tailgate  10 . From this disengaged position, the shield  24  is slid in an engaging direction  46  until the extending tongue  34  is engaged by a receptor  40  and the tab  36  is blocked in the engaging direction  46  by an outwardly projecting support member  45 . The shield  24  is then locked into place by installing the cover  20  onto the housing  18 . The cover  20  has a cover projection  58  that overlays the tailgate  18 , covering the tab opening  48  and restraining any movement of the tab  36  in the disengaging direction  43  with a shield retainer  51 . Removal is the reverse of the above. 
     Other modifications may be made to the illustrated embodiments consistent with the invention. Therefore, the invention lies in the claims hereinafter appended.