Abstract:
A screwless technique for mounting a circuit board in a computer chassis is provided in which circular portions of keyhole-shaped mounting openings in the circuit board body are first moved downwardly over notched chassis mounting bosses. The circuit board is then forwardly moved transversely to the bosses to move opening edge portions of the circuit board body into the boss notches in a manner releasably preventing the circuit board from being lifted off the bosses. A retaining bracket is placed adjacent a body edge of the installed circuit board to block the board against rearward releasing movement relative to the chassis bosses.

Description:
The following is a divisional of application Ser. No. 09/523,835, filed on Mar. 13, 2000 now U.S. Pat. No. 6,385,051. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to electronic apparatus and, in a preferred embodiment thereof, more particularly relates to apparatus and methods for operatively mounting circuit boards on support structures such as computer chassis walls. 
   2. Description of Related Art 
   For many years, the conventional method of installing a circuit board, such as the motherboard, in a computer was to simply screw the board substrate to bosses or other mounting structures suitably mounted on a chassis wall portion of the computer. This circuit board installation method substantially increased the time, and thus the cost, required to construct the computer in addition to adding to the complexity and difficulty of assembling, and later disassembling and servicing the computer. 
   A relatively recent improvement in the mounting of a main circuit board in a computer is illustrated and described in U.S. Pat. No. 5,754,396 to Felcman et al entitled “MODULAR DESKTOP COMPUTER HAVING ENHANCED SERVICEABILITY In the desktop computer illustrated and described in this patent, the motherboard is mounted on a tray structure which may be slid into and out of the computer chassis to install and later remove the motherboard for access and service purposes. 
   While this tray support concept hastens and reduces the cost associated with initially installing the motherboard in the chassis and subsequently removing the motherboard for service and replacement, it also increases the manufacturing cost of the computer since the motherboard must be produced and spared with this auxiliary support tray secured thereto. 
   It thus can be seen from the foregoing that it would be desirable to provide for the cost effective, screwless installation and removal of a circuit board within a computer without the necessity of securing to the computer an auxiliary support tray or other cost increasing mounting structure. It is to this design goal that the present invention is directed. 
   SUMMARY OF THE INVENTION 
   In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, electronic apparatus is provided which is representatively in the form of a desktop computer. The computer has a circuit board, illustratively a motherboard, and a support structure, representatively a chassis wall. According to a key aspect of the present invention, the circuit board is operatively secured to the chassis wall without the use of screws or any sort of support tray secured to the circuit board. 
   Using a screwless circuit board attachment technique of the present invention, cooperatively engaged locking structures are carried by the circuit board and the support structure. The cooperatively engaged locking structures releasably hold the circuit board on the support structure and permit removal of the circuit board from the support structure in response to sequential movement of the circuit board relative to the support structure in (1) a first direction and (2) a second direction transverse to the first direction. A retaining structure releasably blocks movement of the circuit board in the first direction relative to the support structure, thereby releasably retaining the circuit board on the support structure. 
   In a preferred embodiment of the screwless circuit board attachment apparatus, the openings have generally keyhole-shaped configurations and are formed in a substrate body portion of the circuit board, and the projections are carried on the chassis wall portion, extend partly through the substrate openings and have notch portions receiving opening edge portions of the substrate body portion. 
   To rapidly install the circuit board on the chassis wall projections, the substrate body openings are moved over outer end portions of the projections, and the substrate body is moved parallel to its plane to cause the opening edge portions to enter the notches on the projections and thereby block removal of the circuit board from the projections in a direction parallel to their lengths. A retaining bracket member is then moved into a position in which it blocks movement of the circuit board to move its opening edge portions out of the projection notches. 
   When it is later desired to remove the circuit board, the retaining bracket is simply moved away from its circuit board blocking position, the circuit board is moved transversely to the projections to remove its opening edge portions out of the projection notches, and the circuit board is lifted off the projections. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partially exploded rear side perspective view of a portion of a representative computer chassis and a motherboard installable in the chassis using unique screwless installation apparatus and methods embodying principles of the present invention; 
       FIG. 2  is an enlarged scale top plan detail view of the dashed circle area “2” in  FIG. 1  illustrating a keyhole-shaped mounting opening formed in the motherboard substrate body; 
       FIG. 3  is an enlarged scale perspective view of a rear corner portion of the chassis illustrating a pair of upwardly projecting mounting bosses on its bottom side wall, and a retaining bracket slot formed in the chassis; 
       FIG. 4  is a rear side perspective view of the chassis with the motherboard mounted therein and a rear retaining bracket structure being secured to the chassis and ready to be pivoted forwardly to its board retaining position; 
       FIG. 5  is an enlarged scale perspective detail of a rear corner portion of the chassis illustrating the manner in which the retaining bracket structure is removably secured to the chassis. 
       FIG. 6  is an enlarged scale partially elevational cross-sectional view taken along line  6 — 6  of FIG.  4  and illustrating the manner in which the mounting bosses captively retain the motherboard in its installed orientation relative to the bottom chassis wall; and 
       FIG. 7  is a rear side perspective view of the chassis illustrating the motherboard installed therein and captively retained within the chassis by the retaining bracket structure which has been swung inwardly to its locking position. 
   

   DETAILED DESCRIPTION 
   Perspectively illustrated in  FIGS. 1 ,  3  and  4  is a bottom portion of a generally rectangular sheet metal chassis section  10  of a representative desktop computer  12  which also includes a main circuit board or “motherboard”  14 . Motherboard  14  is installable in the chassis  10  using unique screwless installation apparatus and methods of the present invention as subsequently described herein. AS will be readily appreciated by those of skill in this particular art, various computer components, such as drive units and other components and interconnecting cabling and the like have been removed from the chassis interior for purposes of illustrative clarity. Additionally, the top cover portion of the overall chassis structure has been removed for illustrative purposes. 
   Chassis  10  has a bottom wall  16  with a rear side edge  18 , left and right upstanding side walls  20  and  22 , and an upstanding front wall  24  extending between the side walls  20  and  22 . An electrical power supply unit  25  of conventional construction is supported on the left side wall  20  for pivotal movement relative thereto between a solid line vertically extending access orientation, and a dashed line operating orientation in which the power supply unit  25  is swung down into the chassis interior in an upwardly spaced relationship with the bottom chassis wall  16 . 
   The motherboard  14  has a generally planar rectangular substrate body  26  having front and rear side edges  28  and  30 , with various electronic components, including a central processing unit  32 , being operatively mounted on the top side of the substrate body  26 . Also mounted on the substrate body  26 , along its rear edge  30  are a series of various input/output components  33 . Formed through the substrate body  26  are several spaced apart mounting holes  34  which form part of the specially designed circuit board mounting system of the present invention. The mounting system also includes spaced apart, upstanding mounting bosses  36  secured to the bottom chassis wall  16 , upstanding left and right rear corner plate portions  38  and  40  of the chassis, and an elongated retaining bracket structure  42 . 
   As best illustrated in  FIG. 2 , each of the motherboard substrate body mounting holes  34  is generally keyhole-shaped, having a circular main portion  44  from which a narrowed straight portion  46  radially outwardly projects. Each of the upwardly projecting mounting bosses (see  FIG. 3 ) Includes a cylindrical base portion  48 , an annular, vertically intermediate notch  50 , and a generally conically-shaped upper end portion  52 . A reduced diameter intermediate cylindrical portion  54  vertically extends between the base portion  48  and the conical upper end portion  52 , and annular upper and lower ledges  56 , 58  are formed by the notch  50 . 
   To rapidly mount the motherboard  14  within the interior of the chassis  10 , without the use of separate fasteners of any sort or securing a tray or other type of mounting structure to the motherboard, the motherboard  14  is simply placed above the bottom chassis wall  16 , with the upstanding chassis mounting bosses  36  in alignment with the circular portions  44  of the substrate body holes  34  (see FIG.  2 ). Next, the motherboard  14  is lowered to cause the conical upper end portions of  52  of the mounting bosses  36  (see  FIG. 3 ) to extend upwardly through the hole portions  44 , and then forwardly shifted relative to the mounting bosses  36  to cause the vertically intermediate boss portions  54  to enter the narrowed radial substrate body hole portions  46 , with the upper and lower annular boss portions  56 , 58  respectively overlying and underlying top and bottom side portions of the substrate body  26  as cross-sectionally illustrated in FIG.  6 . 
   As described above, the substrate body  26 , and thus the entire motherboard  14 , are releasably locked to the bottom chassis wall  16  via the interlockable, or cooperatively engaged, locking assembly comprising the mounting holes  34  and the bosses  36 . 
   The substrate body  26 , and corresponding mounting holes  34 , is disposed onto the bosses  36  in a manner such that, to remove the substrate body  26  from the bosses  36 , the substrate body  26  must be moved rearwardly to remove the intermediate boss portions  54  from the radial hole portions  46 , and then lifted to move the circular hole portions  44  upwardly past the upper conical boss portions  52  to free the substrate body  26  from the bosses  36 . 
   Such rearward shifting of the installed motherboard  14  relative to the bosses  36  is releasably prevented, thereby captively retaining the motherboard  14  on the bosses  36 , using the retaining bracket  42 . After the motherboard  14  is dropped onto and forwardly shifted relative to the bosses  36  as just described, a small outwardly projecting tab  60  on the right end of the retaining bracket  42  (see  FIGS. 1 ,  4  and  5 ) is inserted into a vertical slot  62  formed in the right rear corner plate portion  40  of the chassis  10  (see  FIGS. 1 ,  3  and  5 ). The retaining bracket  42  is then pivoted horizontally toward the rear edge  30  of the motherboard  14 , as indicated by the arrow  64  in  FIG. 4 , until an outwardly projecting tab  66  on the left end of the retaining bracket  42  enters and is latchingly received in a vertical slot  68  in the left rear corner plate portion  38  of the chassis  10  (see FIG.  4 ). This releasably locks the retaining bracket  42  in its  FIG. 7  installed position in which it extends outwardly along and parallel to the rear side edge  30  (see  FIG. 4 ) of the motherboard substrate body  26 . 
   With the retaining bracket  42  in this installed orientation, an inner or front side portion of the bracket defines an abutment which prevents the substrate body  26  from being rearwardly shifted in a manner unlocking it from and permitting it to be lifted off of the chassis bosses  36 . Additionally, suitable openings  33   a  are formed in the bracket  42  that, with the bracket  42  in its installed orientation, complementarily receive rear portions of the various input/output devices as illustrated in FIG. FIG.  7 . 
   When it is desired to remove the motherboard  14  from the chassis  10 , the retaining bracket  42  is simply pivoted outwardly and removed from the chassis  10 , thereby permitting the motherboard  14  to be rearwardly shifted relative to and lifted off the bosses  36  to quickly and easily remove the motherboard  14  from the computer  12 . 
   As can readily be seen from the foregoing, the present invention provides for the screwless installation and removal of a circuit board on and from a support structure in an electronic device such as a computer, without the use of a support tray attached to the circuit board. While the present invention has been representatively illustrated as being used in conjunction with a computer motherboard attachable to a sheet metal chassis wall, it will be readily appreciated by those of skill in this particular art that principles of the invention could also be advantageously employed in an application involving other types of circuit boards attachable to other types of support structures. 
   Additionally, while the interlocking structures used on the circuit board to effect this screwless circuit board mounting representatively comprised projections on the support structure and cooperating openings on the circuit board, it will be readily be appreciated that the projections could alternatively be formed on the circuit board, and the cooperating openings associated with the support structure, if desired. 
   The foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims.