Abstract:
A lock and release mechanism is disclosed which includes an elongated bendable member which engages a lock tab such that when the lock tab is disengaged with the chassis an electronics module can be moved into a plurality of positions, including a service position, a closed position and a removal position. Such a mechanism advantageously provides latch and release functionality using a single part.

Description:
FIELD OF THE INVENTION 
     This invention relates in general to computer systems and, more particularly, to drawer latch and release apparatus for computer systems. 
     DESCRIPTION OF THE RELATED ART 
     Computer systems in general and IBM compatible computer systems in particular have attained widespread use. These computer systems now provide computing power to many segments of today&#39;s modern society. A computer system can usually be defined as a desktop, floor-standing, or portable microcomputer that includes a system unit having a system processor with associated volatile and non-volatile memory, a display monitor, a keyboard, a hard disk storage device or other type of storage media such as a floppy disk drive or a compact disk read only memory (CD ROM) drive. One of the distinguishing characteristics of these systems is the use of a system board or motherboard to electrically connect these components together. A computer server system is an information handling system designed primarily to give computing power to groups of users and is generally purchased by small and large businesses. 
     Several problems arise with the existing servers that have removable systems. One problem is that space in the individual computer chassis is at a premium. Therefore, there is a need to maximize the density of the components in the system. In server systems, maximizing the density causes layering of components. Layering causes accessibility problems during assembly and during servicing of the system. One way to address the accessibility problem is to put system electronics on a metal module that can be slid in and out of the computer chassis like a drawer. However, using a drawer chassis presents additional problems. One problem is that the module may accidentally fall out of the back of the chassis during service. To prevent falling of the module, sliding rails could be used, but such a system would require several assembly operations, multiple parts and an additional cost. What is desired is a latching device that provides more than one locking position, including a position for servicing, that conserves space in the chassis and does not require multiple parts for assembly. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a one-piece apparatus for latching and releasing an electronics module as a drawer in a computer chassis advantageously provides a spring action and a plurality of positions for locking the mother board chassis drawer into place while having only one discrete part. 
     More specifically, an embodiment relates to a latching and release apparatus for use with a system having an electronics module as a drawer in a computer chassis. The latching and release includes a one-piece member that attaches to both the electronics module and to the chassis. The latch and release apparatus includes a locking tab and an actuator as part of a one-piece design. The action of the latch and release apparatus is generally to act as a spring when the thumb actuator is pressed. The lock tab mates with openings in the chassis when the actuator is released, thereby locking the electronics module in one of a plurality of positions including a closed position, a service position and a removal position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings. 
     FIG. 1 is a perspective view of a computer system incorporating a lock and release apparatus including a latch actuator in accordance with an embodiment of the present invention. 
     FIG. 2 is an electronics module drawer inside a computer chassis in closed position showing the latch actuator illustrated in FIG.  1 . 
     FIG. 3 is an electronics module drawer and computer chassis in service position showing the latch actuator illustrated in FIG.  1 . 
     FIG. 4 is a perspective top view of the latch and release apparatus showing a stiffening beam to make the latch bend in the proper place, the actuator, and the tab for assembly to the module. 
     FIG. 5 is a perspective underside view of the latch and release apparatus showing the locking tab. 
     FIG. 6 is a perspective view of the latch and release apparatus inside the electronics module drawer showing how the latch is secured to the planar plate of the electronics module and where the latch bends to lift the locking tab above the bottom of the module. 
     FIG. 7 is an inverted view of the electronics module outside the computer chassis showing a planar plate latch locking tab protruding through a tab hole of the encasement under the electronics module. 
     FIG. 8 shows the computer chassis prior to installation of the electronics module drawer and attachment of the latch and release apparatus to show the slots for closed position, service position and removal position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following sets forth a detailed description of the best contemplated mode for carrying out the invention. The description is intended to be illustrative of the invention and should not be taken to be limiting. 
     FIG. 1 is a frontal pictorial view of a computer system  100  suitable for incorporating a lock and release apparatus. The illustrative computer system  100  is a server which includes an electronics module  110  in a computer chassis  120 . One example of a server is the POWEREDGE 6300 offered by Dell Computer Corporation. The electronics module typically holds a mother board and other electronic devices. FIG. 1 shows actuator slot  103  in the electronics module  110  through which a latch apparatus may be inserted. 
     FIG. 2 shows an electronics module  200  inside a computer chassis  210 , which employs a latch apparatus  220 . The electronics module  200  is shown in closed position inside the chassis  210 . The latch  220  is shown such that the latch actuator  230  protrudes outside the electronics module  200 . Latch  220  is positioned on the bottom of the planar base plate  240  of the electronics module  200 . However, the latch  220  may operate in other positions inside an electronics module in other examples. 
     FIG. 3 shows the electronics module  200  inside the computer chassis  210 . FIG. 3 shows the electronics module  200  in a service position so that electronic devices that are made inaccessible by the electronics module  200  may be reached. FIG. 3 shows the latch actuator  230 , which is part of the latch  220 , secured to the bottom of the electronics module  200 . As shown, the latch is secured to the module  200 . A force applied to the actuator  230  causes the latch  220  to deflect. 
     Referring to FIG. 4, a perspective top view shows an embodiment of the latch  220 . The latch  220  includes an elongated planar member  412  having a length, width, and thickness. The latch  220  is typically constructed of a plastic material such as a polycarbonate, ABS, or polyvinylchloride (PVC) resin, or a blend of Polycarbonate and ABS, such as BAYBLEND produced by BAYER Corporation. The length of the latch  220  is substantially greater than the width, typically about twenty times the width. In various embodiments, the latch  220  may have a length that is generally in a range of five times to fifty times the width or more, depending on the material used to construct the latch  220 . The width of the latch  220  is also substantially greater than the thickness, typically about ten times the thickness. In various embodiments, the latch  220  may have a width that is generally in a range of three times to thirty times the thickness or more, also depending on the material used to construct the latch  220 . The length, width, and thickness of the latch  220  are determined depending on the flexbility, strength, and durability of the material used to construct the latch  220 . 
     The actuator  230  is integrally connected at one end of the elongated planar member  412  of the latch  220  and typically includes a manipulation surface  410  to facilitate application of a force to the latch  220 . The actuator  230  is a tab that is connected to the elongated planar member  412  of the latch  220  and extends from the end of the latch  220  toward a medial portion of the elongated planar member  412  to form a reinforcement beam  480 . The reinforcement beam  480  extends a length generally in a range from about one-third to two-thirds the total length of the latch  220 . Commonly, the reinforcement beam  480  extends about half the total length of the elongated planar member  412  but the extension length varies depending on the material used to construct the latch  220  and a desired position of flexure of the latch  220 . 
     An engagement structure  410  or snap is formed on the end of the elongated planar latch member  220  opposite the actuator  230 . The engagement structure  410  is an insert protrusion that is generally molded to the latch  220  for affixing the latch  220  to the electronics module  200 . The actuator  230 , the reinforcement beam  480 , the engagement structure  410 , and the elongated planar member  412  are generally molded to form a single integral structure of the latch  220 . 
     Referring to FIG. 5, a perspective bottom view shows the latch  220  in an inverted position. A locking tab  530  is molded onto the bottom  510  of the elongated planar member  412  at a position removed from the actuator  230  by a length greater than the length of the reinforcement beam  480 . The locking tab  530  is removed from the actuator  230  beyond the reinforcement beam  480  to a position on the elongated planar member  412  that flexes when a force is applied to the actuator  230 . 
     Referring to FIGS. 6 and 7, a perspective top view and a perspective bottom view show the electronics module  200  with the engagement structure  410  of the latch  220  affixed, or snapped, into a retainer tab  610 . FIG. 6 shows a top view of the electronics module  200  removed from the computer chassis  210 . The retainer tab  610  in the illustrative latch  220  is a sheet metal tab having connection structures that are suitable for firmly attaching the engagement structure  410 . The illustrative electronics module  200  is formed in the shape of a drawer and includes the planar base plate  240 , a front panel  612 , a back panel  614 , and side panels  616  and  618 . An actuator slot (not shown) is formed in the front panel  612  and receives the actuator  230  portion of the latch  220 . The planar base plate  240  includes rails  620  that are cut from the planar base plate  240  and bent perpendicular to the plane of the planar base plate  240  to operate as guides for laterally constraining the latch  220  when attached to the electronics module  200 . 
     A locking tab slot  722  is cut into the planar base plate  240  of the electronics module in a position aligned to receive the locking tab  530 . Accordingly, the length of the elongated planar member  412  from the actuator  230  to the locking tab  530  coincides with the length from the front panel  612  of the electronics module  200  to the locking tab slot  622 . The chassis  210  includes a plurality of slots which receive the locking tab  530  for positioning the electronics module  200  in a plurality of selected positions. 
     When a force is applied to the actuator  230 , the latch  220  bends at a flex region  624 , raising the locking tab  530  of the elongated planar member  412  at least partially out of the locking tab slot  722  and completely out of a slot in the chassis  210 . When the locking tab  530  is flexed out of the slot in the chassis  210 , the electronics module  200  is no longer constrained within the chassis  210  and may be moved. 
     Referring to FIG. 7, a perspective view shows the electronics module  200  in an inverted position so that the bottom side of the planar base plate  240  is directed upward for viewing. A slot  722  is cut and extends fully through the planar base plate  240 . When no force is applied to the actuator  230 , the locking tab  530  protrudes through the elongated planar member  412  via the locking tab slot  722  into a slot in the chassis  210 , fixing the position of the electronics module  200  within the chassis  210 . When a force is applied to the actuator  230 , the elongated planar member  412  bends so that the locking tab  530  no longer protrudes outside the electronics module  200 . The locking tab  530  is lifted to clear a slot in the chassis  210  so that the electronics module  200  may be repositioned with respect to the chassis  210 . 
     Referring to FIG. 8, a perspective view shows the chassis  210  including a plurality of slots for receiving the locking tab  530  through the locking tab slot  722  in the electronics module  200 . The illustrative chassis  210  has a cabinet shelf floor  810  with three slots including an open position slot  850 , a service position slot  860 , and a closed position slot  870 . The plurality of slots permit the electronics module  200  to be positioned into one of a plurality of locations. The position into which the electronics module  200  is removably locked is determined by the location of the slots in the chassis  210 . When the locking tab  530  is inserted into the closed position slot  870 , application of a force to the actuator  230  while pulling the electronics module  200  from the chassis  210  allows the electronics module  200  to be moved from a closed position to another position. The electronics module  200  may be moved to the service position or the removal position, in which the latch holds the electronics module  200  in a position as a safe last stopping point before completely removing the electronics module  200  from the chassis  210 . 
     While the invention has been described with reference to various embodiments, it will be understood that these embodiments are illustrative and that the scope of the invention is not limited to them. Many variations, modifications, additions and improvements of the embodiments described are possible. For example, those skilled in the art will readily implement the steps necessary to provide the structures and methods disclosed herein, and will understand that the parameters, materials, and dimensions are given by way of example only and can be varied to achieve the desired structure as well as modifications which are within the scope of the invention. Variations and modifications of the embodiments disclosed herein may be made based on the description set forth herein, without departing from the scope and spirit of the invention as set forth in the following claims. Furthermore, throughout the claims the term “a” is used to introduce an element but does not in any instance refer to a single or “one” element but instead refers to “one or more than one” element.