CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of and claims priority from U.S. patent application Ser. No. 12/204,613, filed Sep. 4, 2008, entitled “SYSTEM, METHOD AND APPARATUS FOR DOOR LATCHING USING A SPRING LATCH,” which claims priority from Provisional Application No. 60/967,420, filed Sep. 4, 2007, entitled “SYSTEM, METHOD AND APPARATUS FOR DOOR LATCHING USING A SPRING LATCH,” which is hereby fully incorporated by reference herein. This application relates to U.S. patent application Ser. No. 12/204,579, filed Sep. 4, 2008, entitled “SYSTEM, METHOD AND APPARATUS FOR USING OVERMOLDED DAMPENERS TO ABSORB SHOCK AND VIBRATION,” U.S. patent application Ser. No. 12/204,160, filed Sep. 4, 2008, entitled “SYSTEM, METHOD AND APPARATUS FOR DUAL HEATSINK COOLING SOLUTION FOR COMPUTERS,” and U.S. patent application Ser. No. 12/204,586, filed Sep. 4, 2008, entitled “SYSTEM, METHOD AND APPARATUS FOR BATTERY COOLING AND PROTECTION,” each of which is fully incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates generally to providing physical protection to computers and, more particularly, to protecting computers from damage due to ingress of water or other contaminants. 
       BACKGROUND OF THE RELATED ART 
       [0003]    Computers are susceptible to damage from liquids. Ingress of rain and other forms of precipitation can damage or ruin electronic components in a computer. 
         [0004]    Gaskets are frequently used to provide a seal or barrier for liquids. A gasket is a mechanical seal that fills the space between two objects to prevent leakage between the two objects. However, gaskets generally rely on compression between two objects. If the compression has an angled or shear component, the gasket may roll or tear. 
         [0005]    In laptop computers, there may be several doors that have living hinge mechanisms. The problem with living hinge doors is that, the living hinge may not withstand rugged environments and fails over time. 
       SUMMARY OF THE DISCLOSURE 
       [0006]    A computer casing may have an opening that requires sealing against water ingress. Embodiments of a computer may have a door with a spring latch mechanism for inhibiting liquid ingress. 
         [0007]    One embodiment of an apparatus for preventing ingress of liquid into a computer may be directed to computer door having a hinge for rotatable connection to a first side of a recessed opening in a computer casing, a closure mechanism for connection to a second side of a recessed opening in the computer casing, and a layer of material adhered to the inner surface of the door and having a chamfered edge. The closure mechanism may include a bar for movable connection to the door and operable for travel in a first direction or a second direction opposite the first direction, a latch mounted on the bar and oriented in a first direction, and a spring having a first end connected to the bar and a second end connected to the door for biasing the bar in the first direction. In some embodiments, closing the door causes the chamfered edge to contact a surface that is perpendicular to the layer of material and deflect the chamfered edge. Deflection of the chamfered edge may cause the layer of material to seal the opening. 
         [0008]    In some embodiments, the latch comprises a first surface, wherein closing the door causes contact between the first surface of the latch and a locking element of the computer casing to bias the latch in the second direction, wherein continued closing of the door advances the first surface of the latch past the locking element, wherein the latch is free to move in the first direction. The layer of material may comprise natural butyl rubber and may have a thickness between 0.05 inches and 0.15 inches. In some embodiments, the bar is operable for slidable travel in the first direction or the second direction. 
         [0009]    A system for preventing ingress of liquid into the opening may include a door rotatably connected to the computer casing, a layer of material adhered to the door and having a chamfered edge, a bar movably connected to the door and operable for travel in a first direction or a second direction opposite the first direction, and a spring having a first end connected to the bar and a second end connected to the door for biasing the bar in the first direction of travel. Closing the door causes the layer of material to contact a recessed surface of the opening and deflect the chamfered edge to form a seal in the recessed opening. 
         [0010]    Sealing an opening from ingress of water, rain or other liquids through a recessed opening in the computer may involve sealing against an inner wall formed by the recessed opening. An advantage to sealing against an inner wall may be that the size of the recessed opening does not need to be enlarged or reduced and a door providing access to a component in the recessed opening may be flush with the surface of the computer. In some situations, the height or length of a surface of a computer may be restricted. In some situations, the size or arrangement of buttons, ports, or other features of a component in a recessed opening may be close to a recessed wall such that an o-ring would contact the feature. Embodiments of a door and a layer may enable a recessed opening to be sealed using an inner wall of the recessed opening, without contact against a component or features of a component in the recessed opening, and may also be flush with a surface of the computer casing. 
         [0011]    Other objects and advantages of the embodiments disclosed herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A more complete understanding of the present disclosure and the advantages thereof may be acquired by referring to the following description, taken in conjunction with the accompanying drawings in which like reference numbers indicate like features and wherein: 
           [0013]      FIGS. 1A-1C  depict perspective views of one embodiment of computer; 
           [0014]      FIGS. 2A-2C  depict views of a laptop having an opening  200  with inner walls recessing some depth from the surface; 
           [0015]      FIGS. 3A-3C  depict perspective views of a door with a portion of a hinge; 
           [0016]      FIGS. 4A and 4B  depict side views of a layer of a resilient material for adhering to a door; 
           [0017]      FIGS. 5A and 5B  depict side views of one embodiment of the layer of material in  FIGS. 4A and 4B  having a chamfered edge; 
           [0018]      FIGS. 6A and 6B  depict views of a portion of one embodiment of a closure mechanism; 
           [0019]      FIG. 7  depicts views of one embodiment of a lock; and 
           [0020]      FIG. 8  depicts an exploded view of one embodiment of a door latching system using a spring latch. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The inventive system, method and apparatus for door latching using a spring latch and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments detailed in the following description. Descriptions of well known starting materials, manufacturing techniques, components and equipment are omitted so as not to unnecessarily obscure the disclosure in detail. Skilled artisans should understand, however, that the detailed description and the specific examples, while disclosing preferred embodiments of the disclosure, are given by way of illustration only and not by way of limitation. Various substitutions, modifications, and additions within the scope of the underlying inventive concept(s) will become apparent to those skilled in the art after reading this disclosure. Skilled artisans can also appreciate that the drawings disclosed herein are not necessarily drawn to scale. 
         [0022]    As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, product, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such process, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive “or” and not to an exclusive “or”. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). 
         [0023]    Additionally, any examples or illustrations given herein are not to be regarded in any way as restrictions on, limits to, or express definitions of, any term or terms with which they are utilized. Instead, these examples or illustrations are to be regarded as being described with respect to a particular embodiment and as illustrative only. Those of ordinary skill in the art will appreciate that any term or terms with which these examples or illustrations are utilized encompass other embodiments as well as implementations and adaptations thereof which may or may not be given therewith or elsewhere in the specification and all such embodiments are intended to be included within the scope of that term or terms. Language designating such non-limiting examples and illustrations includes, but is not limited to: “for example,” “for instance,” “e.g.,” “in one embodiment,” and the like. 
         [0024]    Embodiments described herein may be useful for constructing a rugged computer that can withstand harsh and extreme conditions. Computers, particularly laptop computers, are used by the military, commercial and individuals in situations in which the computer may be dropped, may encounter vibration for periods of time, may be exposed to rain, dust, salt water environments or high humidity environments, and the like. 
         [0025]      FIGS. 1A-1C  depict perspective views of one embodiment of computer  100 . DELL Computers, of Round Rock, Tex. is one example of a vendor of computer  100 . Computer  100  may have a power port, WiFi port, a 1394 port, a PCMCIA slot, a Smart Card Reader slot, one or more USB ports, a media bay to support an optical storage medium (such as a CD-ROM), an RJ45 port, an RJ11 port, a serial communication port, a battery door or other openings  200  around the outside, through which water may ingress into computer  100 . Although a laptop computer is shown, embodiments may be used with desktop computers, servers, handhelds, or other computers  100 . Military standard MIL-STD 810F describes some performance standards regarding temperature, shock/drop, moisture, altitude and others to which computer  100  may be exposed. 
         [0026]      FIGS. 2A-2C  depict views of laptop  100  having opening  200  with inner walls  210  recessing some depth from surface  102 . The overall dimensions of computer  100  may determine the maximum size of opening  200 . For example, a thinner computer  100  may restrict the height of opening  200 , or the presence of nearby ports, shock dampeners  103  or vents  104  may determine the maximum width of opening  200  or the width of the surface around opening  200 . U.S. Pat. No. 7,965,500 entitled “System, Method and Apparatus for Using Overmolded Dampeners to Absorb Shock and Vibration,” which is hereby incorporated by reference, describes embodiments of shock dampeners  103  that may be positioned on computer  100  which may limit the maximum width of opening  200  or the surface area around opening  200 . 
         [0027]    In some embodiments, the area around opening  200  is too small for a gasket or o-ring. If the area surrounding the opening is narrow, the height and width or diameter of a gasket must also be small, which increases the risk that the gasket may roll or tear when closing door  120  over the opening. If a gasket is too thick, the gasket may add undesirable weight or door  120  for providing access to the opening may protrude an undesirable amount so that door  120  is no longer flush with the side of the computer. 
         [0028]    As shown in  FIGS. 2A-2C , a component such as DVD  104 , AV-WiFi area  105 , VGA area  106 , or the like may be positioned in recessed opening  200  in laptop  100 . The dimensions of a component installed in recessed opening  200  may determine the minimum width of opening  200 . In some embodiments, a component may have buttons  107 , switches  108 , slots  109  or ports  101  such that it is undesirable to apply pressure to the component surface. In some embodiments, the shape or size of a component may be such that the face of the component is recessed some distance from surface  102  of laptop  100 , thereby forming inner walls  210 . 
         [0029]      FIGS. 3A-3C  depict perspective views of door  120  with portions of hinge  143 . In some embodiments, such as depicted in  FIGS. 3A and 3B , door  120  may have hinge having pins  32  manufactured separately and then connected to door  120 . In some embodiments, such as  FIG. 3C , pins  32  may be integral to door  120 . Door  120  may also include locking elements  157  for engagement by a latch, and opening  122 , which may provide access for a lock, discussed below. Door  120  may be manufactured from any lightweight rigid material. In some embodiments, door  120  may be manufactured from a zinc alloy or a magnesium alloy such that door  120  is rigid but adds very little to the overall weight of computer  100 . Door  120  may include protrusions  121  to assist with positioning or alignment of layer  150 , discussed below. 
         [0030]      FIGS. 4A and 4B  depict side views of layer  150  of a resilient material for adhering to door  120 . Layer  150  may be manufactured from any resilient material that allows layer  150  to seal against inner surface  210  of opening  200 . In one embodiment, a resilient material comprises natural butyl rubber (NBR). In some embodiments, layer  150  may be manufactured from Dynaflex G 7 930-9001-02 TPE, hardness 30 Shore A. In some embodiments, layer  150  may be manufactured from Versa Flex CL2003X Ultra-Soft TPE, hardness 30 Shore 00. In some embodiments, layer  150  having a thickness of 0.10 inches may inhibit ingress of water or other liquids in computer  100 . 
         [0031]    Layer  150  may be thermally, mechanically or chemically adhered to door  120 . In some embodiments, layer  150  having an adhesive backing may be adhered to door  120 . In some embodiments, adhesive used to mate layer  150  to door  120  may be 3M 467®. 3M 467 is manufactured by The 3M Company, St. Paul, Minn. When door  120  is in a closed configuration, layer  150  may form a seal against inner walls  210  inside opening  200  to inhibit water or other liquids from seeping, flowing, or otherwise entering computer  100  through opening  200 . In some embodiments, contact between layer  150  and inner surface  210  of opening  200  may create a seal to inhibit ingress of liquids into computer  100 . 
         [0032]    In some embodiments, layer  150  may include chamfered edge  152  to provide a seal against inner surface  210 . Chamfered edge  152  may refer to a continuous edge around the perimeter of layer  150  or may refer to the combined edges of two or more sides of layer  150 . In some embodiments, layer  150  may have chamfered edge  152  extending around four sides with radiused corners. In some embodiments, chamfered edge  152  may be formed such that, when door  120  is closing, chamfered edge  152  contacts inner wall  210  to cause chamfered edge  152  to deflect by some angle, which may be referred to as a lag angle.  FIGS. 5A and 5B  depict side views of one embodiment of layer  150  having chamfered edges  152 . In  FIG. 5A , chamfered edge  152  is shown in an undeflected state. In  FIG. 5B , layer  150  is shown with chamfered edge  152  in a deflected state with an associated angle θ (theta). The chamfer angle of chamfered edge  152  and the material used to form layer  150  may determine the angle θ (theta) to which chamfered edge  152  may deflect. 
         [0033]    If the chamfer angle of chamfered edge  152  is too small, layer  150  may not form a proper seal and liquid may bypass layer  150 . If the chamfer angle of chamfered edge  152  is too large, layer  150  may overcompress. Overcompression may result in excess material such that layer  150  does not seal properly or door  120  may be unable to close such that liquid may bypass layer  150 . Over time, overcompression may lead to tearing, cracking, deformation, or some other material failure of layer  150 , which may allow liquid to bypass layer  150  and enter computer casing  20 . In some embodiments, the chamfer angle may be between 40 and 50 degrees. 
         [0034]    Layer  150  may provide other advantages as well. An advantage of layer  150  having chamfered edge  152  may occur when chamfered edge  152  contacts inner surface  210  of opening  200 . In some embodiments, the chamfer angle of chamfered edge  152  may be selected such that a desired resistive friction force is generated during closure of door  120 . The friction force may resist closure of door  120  such that closure of door  120  is assured only when a desired force is applied. If a user of computer  100  is wearing gloves, or visibility is poor, or the computer is in a noisy environment, a tactile sensation provided by door  120  may be a reliable indicator when door  120  is closed to inhibit ingress of liquid. 
         [0035]    Another advantage of layer  150  may be the minimal thickness required to form a good seal. In some embodiments, layer  150  configured to inhibit water ingress based on a 40 psi/4 inches per hour standard may be between 0.2 mm and 0.4 mm thick. The minimal thickness and/or lack of a groove to retain layer  150  may result in lower overall weight of door  120 , and less manufacturing complexity and cost. For example, layer  150  may have openings  151  at various locations to accommodate features  121  of door  120 . Positioning openings  151  on features  121  may be easier than positioning an o-ring in a groove or a gasket on an edge. 
         [0036]      FIG. 6  depicts a perspective view of a portion of one embodiment of closure mechanism  160 . Closure mechanism  160  positioned on computer  100  may connect to door  120  to ensure a seal between layer  150  and inner surface  210  remains intact even in extreme conditions. In some embodiments, closure mechanism  160  may ensure water with a pressure of 40 psi and a flow rate of 4 inches per hour does not enter computer  100 . 
         [0037]    Closure mechanism  160  may include bar  162  having latches  164 . In some embodiments, bar  162  may be operable to travel in a first direction as indicated by arrow  165 A and a second direction opposite the first direction as indicated by arrow  165 B (i.e., bidirectional movement). A spring may apply a force to bar  162  to bias bar  162  in the first direction. Biasing bar  162  in the first direction may provide for automatic locking of closure mechanism  160 . In some embodiments, closure mechanism  160  may include a thumb slide  168 . 
         [0038]    In some embodiments, closure mechanism  160  may automatically engage door  120  to inhibit ingress of water or other liquids. In some embodiments, bar  162  of closure mechanism  160  may move in response to contact with locking element  157  of door  120  such that latch  164  automatically engages locking element  157 . In one embodiment, closing door  120  may cause contact between latch  164  and locking element  157 . Contact between latch  164  and locking element  157  may bias or otherwise cause latch  164  to move in second direction  165 B. As door  120  closes, latch  164  may pass by locking element  157  such that locking element  157  no longer biases latch  164  in the second direction and latch  164  is free to move in the first direction. Latch  164  moving in the first direction may engage locking element  157 . As door  120  closes, layer  150  may form a seal against inner surface  210  such that when latch  164  engages locking element  157 , layer  150  inhibits ingress of water through opening  200 . 
         [0039]      FIG. 6B  depicts a close up view of a portion of closure mechanism  160 . Latch  164  may have first surface  164 A and second surface  164 B to enable automatic latching of door  120 . In one embodiment, as door  120  is closing, first surface  164 A of latch  164  contacts a surface of locking element  157 . As latch  164  passes by locking element  157 , latch  164  may move in the second direction, causing bar  162  to move in the second direction as well. As door  120  is closed further, bar  162  and latch  164  may be biased in the second direction such that latch  164  is able to pass by locking element  157 . As latch  164  passes by locking element  157 , first surface  164 A of latch  164  may no longer contact a first surface of locking element  157  and latch  164  may be free to move in the first direction. As latch  164  moves past locking element  157 , latch  164  may move in the first direction to engage locking element  157 . In some embodiment, first surface  164 A of latch  164  may engage a similar shaped or textured surface of locking element  157 . 
         [0040]      FIG. 7  depicts views of one embodiment of lock  169 . Lock  169  may prevent latch  164  from disengaging from locking element  157  to ensure door  120  remains closed. In some embodiments, a person may move lock  169  by moving contact point  177  on the outside of door  120  to bias protrusion  174  extending through opening  122  to the inside of door  120 . 
         [0041]      FIG. 8  depicts an exploded view of a door latching system, which may include door  120  connected by hinge  143  and pins  32  to a portion  800  of computer  100 , layer  150  having chamfered edge  152  for contact with inner walls  210  of openings  200  in computer  100 , and closure mechanism  160  having latches  164  for engaging locking elements  157  on door  120 . In some embodiments, a door latching mechanism may include spring  166 . Spring  166  may provide a spring force to bar  162  sufficient to bias bar  162  in the first direction. Spring  166  may be a compression, tension, or torsion spring. The spring constant, wire diameter, mean coil diameter, number of coils, initial tension, and maximum deflection for spring  166  may be selected to ensure door  120  remains closed and water at a pressure standard of 40 psi and a flow standard of 4 inches per hour is inhibited from entering opening  200 . In one embodiment, spring  166  may be a tension spring with a spring constant between 3.5 lbs/inch and 4.0 lbs/inch. The friction force between second surface  164 B of latch  164  and second surface  157 B of locking element  157  or the force exerted by spring  166  on bar  162  may ensure latch  164  remains engaged to locking element  157 . When latch  164  is engaged with locking element  157 , door  120  may be inhibited from opening and the seal between layer  150  and inner surface  210  may be maintained. In some embodiments, a seal between layer  150  and inner surface  210  that inhibits liquid ingress up to 40 psi at 4 inches per hour may be maintained by door  120  having latch  164  engaging locking element  157 . 
         [0042]    In order for door  120  to be opened, closure mechanism  160  may include a release mechanism. In one embodiment, a release mechanism may involve biasing bar  162  in the second direction such that latch  164  disengages from second surface  157 B of locking element  157 . Biasing bar  162  in the second direction may involve overcoming the spring force generated by spring  166 . Biasing bar  162  in the second direction may involve pulling on a component, pushing on a component, or rotating a component to overcome the spring force generated by spring  166 . For example, closure mechanism  160  may include thumb slide  168  connected to bar  162 . A user may slide thumb slide  168  in the second direction to bias bar  162  such that latch  164  disengages from locking element  157 . 
         [0043]    A release mechanism may assist with opening door  120  in addition to disengaging latch  164  from locking element  157 . In one embodiment, biasing bar  162  in a second direction may cause contact between latch  164  and a second portion of locking element  157  to bias door  120  away from locking element  157 . 
         [0044]    Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
A computer casing may have an opening that requires sealing against water ingress. A system for preventing ingress of liquid into the opening may include a door rotatably connected to the computer casing, a layer of material adhered to the door and having a chamfered edge, a bar movably connected to the computer casing and operable for travel in a first direction or a second direction opposite the first direction and a spring having a first end connected to the bar and a second end connected to the computer casing for biasing the bar in the first direction of travel. Closing the door causes the layer of material to contact a recessed surface of the opening and deflect the chamfered edge to form a seal in the recessed opening. Moving the bar in the first direction retains the door relative to the computer to maintain the seal formed by the layer of material.