Abstract:
The invention provides for an apparatus that secures one or more expansion boards to a motherboard. A single type of adjustable retention block can be used to engage and secure expansion boards of various sizes. The retention block secures an expansion board in a groove of the retention block along the edge of the expansion board. By this attachment, the retention block avoids contact with the electrical components of either the expansion board or the motherboard.

Description:
TECHNICAL FIELD 
     The present invention is directed toward an apparatus and method for securing one or more expansion boards of a computer. 
     BACKGROUND OF THE INVENTION 
     The functionality of computers is enhanced by including the ability to accept peripheral systems into the computer. One of the primary means of providing added functionality is to include slots into which additional “expansion boards” can simply be inserted. It is a standard practice in the art of computer design to provide for the mounting of expansion boards perpendicular to a main computer board or “motherboard.” Graphics cards, sound cards, video cards, and modem cards are typical expansion boards. 
     Because expansion boards are not soldered into place on the motherboard, it is possible that the boards will become dislodged, lose electrical connectivity, and cease to function properly. A number of designs have been proposed to adequately secure expansion boards to the motherboard. The standard configuration uses one screw per expansion board to secure one side of a mounting plate to the chassis of a computer. The mounting plate is secured to the expansion board. The other end of the mounting plate is inserted into a slot in the chassis. The expansion board is thus fastened relative to one wall of the computer chassis. This design assumes that the chassis is adequately stiff to prevent the motherboard, which is attached to one wall of the chassis, and the expansion board, which is attached to a second wall of the chassis, from moving relative to one another. 
     It has become evident to those skilled in the art that an expansion board may still become dislodged from the motherboard even though fastened to one side of the computer chassis. Expansion boards are particularly susceptible to becoming dislodged when the board is located away from a wall of the chassis. When a board is located away from the wall of the chassis, that is, near the middle of the computer box, there is a lack of lateral stiffness in the wall of the chassis to which the motherboard is connected. Therefore, flexing of the chassis wall to which the motherboard is connected causes relative movement between the motherboard and the expansion board. Consequently, shaking of the computer or flexing of the chassis during shipping or handling can result in disconnection of expansion boards from the motherboard. Disconnection is also possible with computers used in non-stationary applications. 
     It can be a major inconvenience to a computer user when an expansion board is dislodged. For a user unfamiliar with the symptoms of the problem, it appears that the computer is materially defective. Even after the problem is identified, it is inconvenient and time consuming to partially disassemble the computer and re-seat the expansion boards. The superior alternative is to prevent the expansion boards from ever becoming dislodged from the motherboard. 
     The problem of expansion type boards becoming unseated has been addressed by the prior art. For example, in U.S. Pat. No. 5,603,628 a pair of straps is used to hold a circuit board in a connector slot. A problem with the &#39;628 patent design is that the straps pass over and through the components of the board. Therefore, there is a possibility of damage to the board and the components of a board during installation or adjustment of the straps. Additionally, the &#39;628 patent requires that connection anchors be added to the connector slot. The anchors not only broaden the connector slot and consume motherboard area, but also require special manufacturing. 
     The specific problem of expansion board retention in a personal computer was addressed in U.S. Pat. No. 5,715,146. However, the &#39;146 patent requires separate size adapter members to adequately secure expansion boards of differing heights. For each height of expansion board, a different size adapter must be added to the post member that supports the board. With different size adapters, production costs are increased and the possibility of manufacturing errors increases. 
     The prior art fails to provide an economical expansion board retention system that does not interfere with the components of the expansion board or consume motherboard area. Under the prior art, numerous adapters of varying sizes may be required to compensate for the fact that expansion board cards are not uniform in height. Consequently, there is a need for an apparatus and method that adequately secures expansion boards to a motherboard without interfering with the components of the expansion board or the components of the motherboard. An improved apparatus would reduce the number of parts required to effect stabilization of the expansion boards. 
     SUMMARY OF THE INVENTION 
     One embodiment of the invention is a retention block for securing an expansion board. The embodiment has a base with a fastener groove for accepting a fastener and a nose opposite to the base for securing the expansion board. 
     Another embodiment of the invention is a computer system comprising: a chassis; a support rail coupled to the chassis; a fastener interfacing with the support rail; a retention block coupled to the fastener including a base with a fastener groove for accepting the fastener and a nose at the opposite end of the retention block from the base; and an expansion board interfacing with the nose of the retention block, the expansion board being secured relative to the chassis to prevent electrical disconnection of the expansion board. 
     Still another embodiment of the invention is a method of manufacturing a computer system comprising the acts of: inserting an expansion board into a slot on a computer motherboard; adjusting the position of the retention block so that the nose of the retention block interfaces with the expansion board; and attaching the base of a retention block to a support member with a fastener. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a retention block. 
     FIG. 2 is an alternative perspective view of a retention block. 
     FIG. 3 is a top perspective view of a computer system with portions of the chassis and components of the computer system removed to show securing of expansion boards. 
     FIG. 4 is an enlarged top perspective view of components of the computer shown in FIG.  3 . 
     FIG. 5 is a flowchart illustrating a method of manufacturing a computer. 
     FIG. 6 is a side elevation view of an embodiment of the invention showing a method of manufacturing a computer. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention are directed toward a computer system with a retention block and supporting structure capable of securing an expansion board such as a peripheral component interconnect (PCI) expansion board to a motherboard. By use of embodiments of the invention, expansion boards are prevented from disengaging from the motherboard. An expansion board that disengages from the motherboard loses electrical connectivity and becomes inoperative. 
     DESCRIPTION OF AN EMBODIMENT OF THE RETENTION BLOCK 
     FIGS. 1 and 2 show a retention block  1  that is used to secure an expansion board in an embodiment of the invention. In one embodiment, the retention block  1  is composed of a plastic having a minimum flame rating of 94V-2 such as Geon Co., type M3750 or 87241, or a polycarbonate material. 
     Base 
     As illustrated in FIGS. 1 and 2, a base  2  of the retention block  1  has a fastener groove  3  for accepting a fastener. The base  2  designates an end of the retention block  1 . In an embodiment of the invention, a radius  4  is greater than twenty percent of the thickness of the retention block  1 . In addition, the base  2  is formed to have a plurality of grooves such as first groove  5  and second groove  6 . First groove  5  and second groove  6  receive a portion of a support structure employed to support the retention block  1 . The fastener groove  3  may have chamfered edges  7  as shown in FIGS. 1 and 2. 
     Nose 
     The nose  8  of the retention block  1  is on the opposite side of the retention block  1  from the base  2 . An embodiment of the invention has a chamfer  9  that has a length greater than twenty percent of the thickness of the retention block  1 . Another embodiment of the invention may have a rounded edge (not shown) rather than a chamfered edge as shown. As illustrated in FIGS. 1 and 2, there is a board groove  10  through the nose  8  for receiving a portion of the expansion board to be secured. Note that board groove  10  as well as second groove  6  may extend between the base  2  and the nose  8 . 
     Description of an Embodiment of the Computer System 
     FIG. 3 shows a computer system  11  with a chassis  12  that is coupled to a support rail  13  that in turn interfaces with a first fastener  14  and is coupled to a first retention block  15 . Similarly, a second fastener  16  interfaces with the support rail  13  and is coupled to a second retention block  17 . As shown in FIG. 4, a first nose  8  of the first retention block  15  interfaces with a first expansion board  18  to secure the first expansion board  18  relative to the chassis  12  to prevent electrical disconnection of the first expansion board  18  from a slot  19  in the motherboard  20 . Similarly, a second nose  8 ′ of the second retention block  17  interfaces with a second expansion board  21  to prevent electrical disconnection of the second expansion board  21  from a slot (not shown) in the motherboard  20 . Note that various components of a typical computer system are omitted from the drawings showing the computer system  11  to provide a clearer representation of the components illustrated. 
     Chassis 
     The chassis  12  shown in FIG. 3 is shown with one wall removed and with the connection areas for the support rail  13  cut away for clarity. The chassis shown is a chassis for a tower configuration computer; however, embodiments of the invention work equivalently for other computer configurations. The motherboard  20  is connected to a wall  22  of the chassis  12 . 
     Support Rail &amp; Fasteners 
     The support rail  13  is coupled to the chassis  12 . In the embodiment illustrated, the support rail  13  snaps into the chassis  12  through snap-in connectors  23 . The support rail  13  shown in FIGS. 3 and 4 is a channel member with a web  24 , an upper flange  25  and a lower flanges  26 . Other structural shapes would be equally well-suited to provide support. The support rail  13  has a connection slot  27  through which fasteners  14  and  16  interface with the support rail  13  and couple to the retention blocks  15  and  17 . The function of the connection slot  27  could be equivalently accomplished within the claims of the invention by a plurality of holes in the support rail  13 , or by other equivalent structures. Fasteners  14  and  16  are screws in the embodiment illustrated in FIGS. 3 and 4. 
     Retention Blocks 
     The first retention block  15  and the second retention block  17  are geometrically and compositionally as described in the description of the first embodiment above. 
     Referring now to FIGS. 1,  2 , and  4 , first retention block  15  is coupled to the fastener  14  through the fastener groove  3  in the base  2  of the first retention block  15 . Note that the retention block  1  is represented in FIGS. 3 and 4 as first retention block  15  and second retention block  17  to distinguish the alternative orientations of the retention block  1 . At the orientation of first retention block  15  shown in FIG. 4, the second groove  6  in the first retention block  15  is engaged with the upper flange  25  of the support rail  13  through approximately one half of the length of the second groove  6 . Similarly, though obstructed from view, the first groove  5  is engaged with the lower flange  26 . The nose  8  of the first retention block  15  is shown interfacing with the first expansion board  18  through board groove  10  of first retention block  15 . 
     The coupling of the fastener  16  to the second retention block  17  is similar to the coupling described immediately above except that the second retention block  17  is rotated 180 degrees about its longitudinal axis to interface with the second expansion board  21 . In this orientation, the second grove  6  is engaged with the lower flange  26  of the support rail  13  in the area of the base  2 . The first groove  5  is engaged with the upper flange  25 . The interface of the nose  8 ′ of the second retention block  17  is similar to the interface described with the first retention block but at a different angle relative to the expansion board. This results from the fact that the second expansion board  21  is not as tall as the first expansion board  18 . Height of the expansion boards for the purpose of discussion of the invention will be referred to as the dimension perpendicular to the motherboard. As illustrated above, a single size and shape retention block can be used to secure expansion boards of different heights by. alternatively positioning the retention blocks. 
     Expansion Boards 
     Referring now to FIGS. 3 and 4, the first expansion board  18  interfaces with the nose  8  of the first retention block  15  as described above. A portion of the first expansion board  18  is shown cut away to provide illustration of the second expansion board  18  and the second retention block  17 . In an embodiment of the invention, the first expansion board  18  and the second expansion board  21  may be PCI expansion boards. 
     The first retention block  15  is positioned to interface with the first expansion board  18  to prevent electrical disconnection of the first expansion board  18  from the slot  19  in the motherboard  20 . With the embodiment shown, not only is the first expansion board  18  connected by conventional means with a mounting plate  28  connected to the chassis  12 , but the first retention block  15  interfaces with the first expansion board  18  as described above. The invention thus provides additional stabilization to the electrical connection between the first expansion board  18  and the slot  19 . 
     The second expansion board  21  is an expansion board of less height than the first expansion board  18 , but as illustrated can be secured by a retention block of the same design as the first retention board with an embodiment of the present invention. 
     Method of Manufacturing with an Embodiment of the Invention 
     One embodiment of the invention is a method of manufacturing a computer system. The method, which is shown in FIG. 5, may be accomplished using a retention block  1  as described above. As a first act, an expansion board is inserted into a slot of a computer motherboard. In an embodiment of the invention, the act of inserting an expansion board includes inserting a PCI expansion board. With the expansion board in place, a retention block is adjusted to a position so that a nose of the retention block interfaces with the expansion board and a base of the retention block is in position to be attached with a fastener. The act of adjusting the position of the retention block may include adjusting the position of the retention block so that a board groove in the retention block engages at least a part of the expansion board. Finally, a fastener is used to attach the base of a retention block to a support member. The act of attaching to the base of the retention block may include the act of turning a screw. Methods of attaching to the base such as clipping, pinning, clamping, and others would be adequate and are contemplated by the invention. 
     FIG. 6 shows the nose  8 , of a retention block  15  engaged with an expansion board  18 . A base  2  of the retention block  15  is attached to a support rail  13  with a fastener  14 . Portions of the support rail  13  are cut away for clarity. By tightening the fastener  14 , the retention block  15  is pulled toward the fastener  14  in the direction labeled  30  in FIG.  6 . Because the retention block  15  contacts the support rail  13  along an area  31  and the support rail cannot be pulled further toward the fastener along that area, the base  2  of the retention block  15  rotates about area  31 . The direction of rotation is shown as  32  in FIG.  6 . When the retention block  15  is rotated, the nose  4  of the retention block transmits a load to the expansion board  18 . 
     The transmitted load acts to preload the interface between the retention block  15  and the expansion board  18  and thereby to prevent disengagement of the expansion board from its expansion slot. Therefore, in the embodiment described, tightening the fastener  14  enhances the security of the expansion board  18 . 
     From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modification may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the claims. 
     ADVANTAGES OF THE INVENTION 
     An advantage of the present invention is that expansion boards of an infinite number of heights, within the range of rotation of the retention block, can be secured by a single type of retention block. To adjust a retention block to secure boards of various sizes an operator merely rotates the block to the desired position and fastens the block with a screw. The invention therefore provides for increased efficiencies in the ordering of parts and in the manufacturing of computers. Additionally, the possibility of manufacturing errors due to erroneous part selection by manufacturing operators is reduced. 
     Another advantage of the invention is that it provides for expansion board retention without interfering with the components of either the motherboard or the expansion board. The retention block does not engage the motherboard in any way and only contacts the expansion board along an edge of the board where components can be avoided. 
     Yet another advantage of an embodiment of the invention is that the geometry of the retention block is such that when a fastener is attached to the base of the retention block, the tightened fastener preloads the interface between the nose of the retention block and the expansion board.