Abstract:
In general, in one aspect, the disclosure describes an apparatus that includes a latch to connect a board to a chassis. The apparatus further includes a pull lever to control whether said latch is retracted or extended. The latch connects the board to the chassis when it is extended.

Description:
BACKGROUND 
   Modular computing systems contain many boards and/or interconnects (hereinafter referred to as “boards”) within a rack (chassis). These systems provide large amounts of processing in a small environment. These systems may enable boards to be replaced while the system is still in operation (hot swap boards). Accordingly, the boards within the rack need to be capable of being installed and secured or unsecured and removed from the rack. As the modular computing systems are tightly bundled, mechanisms for installing or removing boards are limited in size and configuration. Moreover, as boards are being replaced while the system is still active speed of replacement is also important. 
   The chassis&#39; are often governed by standards, such as the PCI Industrial Computer Manufacturers Group (PICMG), Advanced Telecommunications Computing Architecture (ATCA) Base Specification, PIGMG 3.0 Revision 1.0, published Dec. 30, 2002 (hereinafter referred to as “the ATCA specification”). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of the various embodiments will become apparent from the following detailed description in which: 
       FIG. 1  illustrates a perspective view of an example chassis, according to one embodiment; 
       FIG. 2  illustrates a perspective view of an example board for use in a chassis, according to one embodiment; 
       FIG. 3  illustrates a perspective view of an example latching mechanism that may be used to easily install, secure and/or remove a board to a chassis, according to one embodiment; 
       FIG. 4  illustrates an exploded view of an example latch mechanism as it would be configured to connect to a board, according to one embodiment; 
       FIG. 5  illustrates a perspective view of an example latch mechanism connected to a face plate, according to one embodiment; 
       FIG. 6A  illustrates an example board and face plate having a non-engaged (secured) latch mechanism, according to one embodiment; 
       FIG. 6B  illustrates a close up of an example latch assemble in an extended (secured) configuration, according to one embodiment; 
       FIG. 7A  illustrates an example board and face plate having an engaged (retracted) latch mechanism, according to one embodiment; 
       FIG. 7B  illustrates a close up of an example latch assemble in a retracted (non-secured) configuration, according to one embodiment; 
       FIG. 8  illustrates a perspective view of a chassis having a board with an example latch mechanism, according to one embodiment; 
       FIG. 9A  illustrates an example extended (secured) latch assembly, according to one embodiment; and 
       FIG. 9B  illustrates an example retracted (non-secured) latch assembly, according to one embodiment. 
   

   DETAILED DESCRIPTION 
     FIG. 1  illustrates a perspective view of an example chassis (rack)  100  for use with embedded computer systems. The chassis  100  includes a housing  110  (e.g., outer shell, walls) and a frame  120  for holding boards  130  (e.g., computers). Only a single board  130  is illustrated installed in the frame  120  and no components are illustrated on the board  130  for simplicity. The frame  120  consists of upper and lower rails  140  (guide rails) that guide the boards into the housing  110 . It should be noted that only the lower rails  140  are visible in  FIG. 1 . As illustrated, the boards  130  reside vertically in the chassis  100 . A back edge (not illustrated) of the boards  130  may plug into a backplane (not illustrated) for communication with other boards  130  in the chassis  100 , adapters (not illustrated) for communicating external to the chassis  100 , and/or a power source (not illustrated) for proving power to the boards  130 . 
     FIG. 2  illustrates a perspective view of an example board  200  for use in the chassis (e.g., chassis  100  of  FIG. 1 ). The board  200  includes various components  210  for performing different functions and adapters  220  for connecting to a backplane, power and/or other interfaces. The board  200  may also include a front face plate  230  to protect the board  200 , to provide status indicators (e.g., LEDs that indicate status of the board), and to provide mechanisms for securing the board  200  in the chassis. The mechanisms used to secure the board  200  in the chassis may include retention screws  240  and handles  250 . The retention screws  240  may be located on the edges of the face plate  230  in alignment with holes in the chassis (e.g., frame  120 ) when the board  200  is appropriately installed. Once the board  200  is installed the retention screws  240  may be pushed into the holes to secure the board  200  to the chassis. The handles  250  may be also be located on the edges of the face plate  230 . The handles  250  may be extended (see top handle) or retracted (see bottom handle). 
   When the handles  250  are extended they may be used to hold the board  200 . A portion of the handle  260  may extend past the face plate  230  toward the board  200  when extended (see top handle). Once the board  200  is installed in the chassis the handle  250  may be retracted (folded in). When the handle  250  is folded in the portion  260  may extend past the edge of the board  200  and possibly past the edge of the face plate  230  and help secure the board  200  to the chassis. 
   Securing the example board  200  to a chassis may require that the retention screws  240  be aligned and then inserted and that the handles  250  be retracted. Likewise, removing the board  200  from the chassis may require that the handles  250  both be extended and that both retention screws  240  be removed. Insertion and removal thus may require two hands of an operator. 
   Chassis&#39; (e.g.,  100  of  FIG. 1 ) and boards (e.g.,  200  of  FIG. 2 ) may be a governed by standards (e.g., the ATCA specification). The standards may control, the size of the chassis, the number of slots in the chassis, the placement of the boards in the chassis, how the boards are secured in the chassis, the size of the boards, where components are mounted on the boards, interfaces to the board, electrostatic discharge (ESD) parameters, as well as other aspects. For example, the ATCA specification requires that the chassis to have an ESD wrist strap terminal and that the terminal be unpainted. 
   The example chassis  100  of  FIG. 1  and board (e.g., ATCA blade)  200  of  FIG. 2  are based on the ATCA specification. When describing various embodiments, specific reference may be made to the ACTA specification for simplicity and ease of understanding. However, the various embodiments are in no way intended to be limited by the ATCA specification or any standards for that matter. Rather, the various embodiments described herein may be applicable to any modular computing system chassis&#39; and boards. 
     FIG. 3  illustrates a perspective view of an example latching mechanism  300  that may be used to easily install, secure and/or remove a board (e.g.,  200 ) to a chassis (e.g.,  100 ). The latching mechanism  300  may include a handle  310 , a pull lever  320 , cables  330  and latch assemblies  340 . The pull lever  320  may be mounted within (integrated with) the handle  310  and be capable of sliding within the handle  310 . As illustrated, the handle  310  has a grove  350  formed in an inner surface with which the pull lever  320  can slide. According to one embodiment, the handle  310  and the pull lever  320  may be a single component with the handle  310  being a fixed outer handle and the pull lever  320  being an internal lever that translates the fixed outer handle. The pull lever  320  may be designed to be ergonomic so a user can easily grab it with comfort. The pull lever  320  may be connected to the cables  330  and the cables  330  may in turn be connected to the latch assemblies  340 . When the pull lever  320  is engaged (e.g., pulled toward the handle  310 ) it may pull the cables  330  toward the handle  310  which in turn pulls the latch assemblies  340  inwards (the latch assemblies  340  are retracted). 
     FIG. 4  illustrates an exploded view of an example latch mechanism as it would be configured to connect to a board  400  (a face plate  410  of the board  400 ). The latch mechanism may include a handle  420 , a pull lever  430 , cables  440  and latch assemblies  450 . The handle  420  may be mounted to a face of the face plate  410  and may be used to carry the board  400 . The pull lever  430  may be capable of sliding within the handle  420 . According to one embodiment, the handle  420  and the pull lever  430  may be a single component. When the pull lever  430  is in an inert position (when no pressure is applied) it may reside near the middle of the handle  420  so that there is room for the pull lever  430  to be activated (pulled toward the handle  420 ) and so that there is room for one to grasp the pull lever  430  (hand can fit between the pull lever  430  and the face plate  410 ). 
   The pull lever  430  may have connecters  460  for securing the cables  440 . The connecters  460  may be located at the end of the pull lever  430  so as not to interfere with the grasping of the pull lever  430 . The connectors  460  may be any type of connection mechanism that will secure the cables  440  to the pull lever  430  (e.g., a clip for grasping the cables  440 , a hole whereby the cables  440  are inserted). The face plate  410  may have holes therein so that the cables  440  can extend through the face plate  410  and connect to the pull lever  430 . The cables  440  may run along the back of the face plate  410  (bottom of the board  400 ) and extend to the outer edges of the face plate  410  and past the outer edge of the board  400 . The cables  440  may be held to the face plate  410  using an attachment mechanism that allows the cable  440  to move along the face plate  410  when the pull lever  430  is moved. The cables  440  may be hidden by a side wall  470  of the face plate  410 . The sidewall  470  may be perpendicular to the faceplate  410  and parallel to the board  400 . 
   The other end of the cables  440  may connect to the latch assembles  450  that extend from the side of the boards  400 . The latch assemblies  450  may include a mating feature  480  to engage a chassis with which the board  400  is installed. When the pull lever  430  is engaged (pulled toward the handle  420 ), the cables  440  are pulled inward and the latch assembles  450  are retracted (pulled inward and disengaged from the chassis). When the pull lever  430  is disengaged the cables  440  and the latch assemblies  450  are extended (engaged with the chassis). 
   Utilizing the latch mechanism enables a user to quickly install, engage, or remove a board  410  from the chassis. To install or remove a board  400 , the pull lever  430  is engaged so that the latch assemblies  450  are retracted and the board  400  can be slid in or out of the chassis. To secure a board  400 , the pull lever  430  is disengaged so that the latch assemblies  450  are extended and engage the chassis. 
   The cables  440  are illustrated as having a bend therein to indicate that the cables  440  extend along the bottom of the board  400  and then extend through the face plate  410 . According to one embodiment, the face plate  410  may include a guide mechanism (e.g., a pulley) to assist the cables  440  in making the turn. 
     FIG. 5  illustrates a perspective view of an example latch mechanism connected to a face plate  510  of a board  500 . The latch mechanism may include a handle  520  and pull lever  530  that are mounted to the front of the face plate  510 . As previously discussed, the pull lever  530  may be mounted within and be capable of sliding within the handle  520 . The latch mechanism may further include cables that connect the pull lever  530  to latch assemblies that engage a chassis. The cables may extend from the pull lever  530  through holes in the faceplate  510  and then run along the underside of the faceplate  510  to the edges of the face plate  510 . At the edge of the face plate  510  the cables may connect to the latch assemblies. The latch assemblies may engage with and secure the faceplate  510  (and the board  500 ) to the chassis. The cable and the latch assemblies are not visible in  FIG. 5  as they are hidden by a sidewall  540  of the face plate  510 . 
   When the pull lever  530  is disengaged the latch assembly may be extended so that it connects to and secures the faceplate  510  and the board  500  in the chassis. When the pull lever  530  is engaged the latch assemblies may be retracted and the face plate  510  and the board  500  could be inserted or removed from the chassis. 
     FIG. 6A  illustrates an example board  600  and face plate  610  having a non-engaged (secured) latch mechanism. The latch mechanism includes a handle  620 , pull lever  630  connected to the face plate  610 , and cables connecting (not visible—hidden behind side wall  640  of face plate  610 ) the pull lever  630  to latch assemblies  650 . The pull lever  630  is not engaged (is not being pulled toward the handle  620 ) so that the latch assemblies  650  are extended from the side of the board  600 . This would be the configuration of the board  600  when it was installed in and secured to the chassis. 
     FIG. 6B  illustrates a close up of an example latch assembly  650  in an extended (secured) configuration. The latch assembly  650  may be in this position when the pull lever (e.g.,  630  of  FIG. 6A ) is not engaged. The latch assembly  650  may include a latch  660 , a spring  670  and a retainer  680 . One end of the latch  660  is attached to the cable (not visible—hidden behind side wall  640  of face plate  610 ). The other end of the latch  660  has a mating feature  690  to engage the chassis (e.g., ATCA chassis). The retainer  680  is attached to the back side of the faceplate  610 . The spring  670  is placed inside of the retainer  680 . The retainer  680  holds the spring  670  and latch  660  in place. The latch assembly  650  is located at a position to ensure that the latch  660  engages/disengages the chassis properly. As illustrated, the spring  670  is extended and the latch  660  is extended toward the end of the face plate  610 . Accordingly, the latch  660  (the mating feature  690 ) would be engaged with the chassis and secure the board  600  and face plate  610  in the chassis. 
   According to one embodiment, the latch assembly  650  may be designed with a geometry that makes it easier to install (e.g., a sloped portion facing the chassis so board  610  can be installed even without engaging (pulling) the pull lever). That is, the latch assembly need not be retracted for installation. 
     FIG. 7A  illustrates an example board  700  and face plate  710  having an engaged (retracted) latch mechanism. The latch mechanism includes a handle  720  and a pull lever  730  connected to the face plate  710 . The pull lever  730  is engaged (e.g., pulled toward handle  720 ) so that the cables (hidden by face plate side wall  740 ) are pulling the latch assemblies  750  toward the pull lever  730  (center of board  700 ). Accordingly, the latch assemblies  750  are retracted from the edge of the faceplate  710 . This would be the configuration of the board  700  when the board  700  was preparing to be installed or removed from the chassis (e.g., hot swap). 
     FIG. 7B  illustrates a close up of an example latch assemble  750  in a retracted (non-secured) configuration. The latch assembly  750  may be in this position when the pull lever (e.g.,  730  of  FIG. 7A ) is engaged. The latch assembly  750  may include a latch  760  having one end attached to the cable and the other end having a mating feature  790  to engage the chassis. The latch assembly  750  may also include a retainer  780  attached to the back side of the faceplate  710  and a spring  770  placed inside of the retainer  780 . As illustrated, the spring  770  is compressed and the latch  760  is retracted from the edge of the face plate  710 . Accordingly, the latch  760  would not be engaged with the chassis. 
     FIG. 8  illustrates a perspective view of a chassis  800  with a board  810  with a latch mechanism  820  mounted on the face plate installed therein. Only a single board  810  is illustrated in the chassis  800  for simplicity. 
   According to one embodiment, when one board is about to be replaced for another board (a hot swap) the system needs to be prepared for the replacement. Accordingly, the system needs to be informed when a hot swap is about to be performed. One possibly for determining when a hot swap is about to be performed is to monitor when a latch (e.g.,  760 ) is disengaged from the chassis. This can be performed by using a switch (e.g., plunger switch) that activates a hot swap signal when the switch is pushed in. 
     FIG. 9A  illustrates an example extended (secured) latch assembly connected to a faceplate  910  of a board  900 . The latch assembly is mounted to the faceplate  910  and includes a latch  920 , a spring  930 , a retainer  940  and a switch  950 . The latch  920  includes a mating end  960  and a shaft  970 . The mating end  960  engages the chassis and the shaft  970  is connected to the cable and has the spring  930  wound therearound. The retainer  940  holds the spring  930  and the latch  920  together and secures them to the face plate  910 . The retainer  940  and the shaft  970  maintained in the retainer  940  rests on top of the switch  950 . As the latch  920  is not being pulled by the cable the spring  930  and latch  920  are not retracted. Accordingly, the switch  950  is not activated (depressed) and the system would not be informed that a hot swap was about to occur. 
     FIG. 9B  illustrates an example retracted (non-secured) latch assembly. The latch  930  is being pulled inward so that the spring  940  and the latch  930  are retracted. Accordingly, the shaft  970  extends past the retainer  940  and activates (depresses) the switch  950  activating a hot swap signal. 
   The activation of a hot swap signal is not limited to use of a switch, or monitoring of the latch assembly. Rather, numerous techniques could be used to initiate a hot swap signal without departing from the scope of the various embodiments. 
   Although the various embodiments have been illustrated by reference to specific embodiments, it will be apparent that various changes and modifications may be made. Reference to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment” appearing in various places throughout the specification are not necessarily all referring to the same embodiment. 
   The various embodiments are intended to be protected broadly within the spirit and scope of the appended claims.