Patent Publication Number: US-2011068587-A1

Title: Integrated latch

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The described embodiments generally pertain to mechanical fastener that is used to join two (or more) objects or surfaces together while allowing for the regular or eventual separation of the objects or surfaces. In particular, the mechanical fastener is a compact integrated latch system well suited for use in small hand held electronic devices. 
     2. Description of the Related Art 
     Many portable electronic devices include enclosures used to contain sensitive electronic components that must be protected from the outside environment. If these enclosures are accessible to a user, then some form of a protection, such as a lid or other such covering, can be used to protect the contents of the enclosure from the outside environment. However, the lid must be able to be removed or at least displaced in order to provide the user with suitable access to the enclosure in order to service any components included therein. For example, if the portable electronic device is powered by replaceable batteries that must be replaced when needed, then the portable electronic device can include an enclosure that can take the form of a battery compartment into which the batteries can be placed. The battery compartment will generally include a lid that can be temporarily removed or set aside in order to provide a user with access to the battery compartment in order to replace any batteries as needed. Generally, the lid is latched into place using a conventional latch system such as that shown in  FIG. 1 . 
       FIG. 1  shows conventional latch system  100 . Conventional latch system includes keeper  102 , latch  104  and lid  106  attached to housing  108  at pivot point P. In a latched state (where lid  106  is in a closed position relative to housing  108 ), keeper  102  is forced up against latch  104  by restoring force F r . In order to provide sufficient torque τ on keeper  102  to maintain lid  106  in a closed state, restoring force F r  is provided some distance/from keeper  102  (i.e., τ=F 1 ×l). For example, if lid  106  is formed of a deformable material, then lid  106  can be considered to include a number of springs distributed along its length that can be approximated as a torsion spring T located at pivot point P with an effective torsion spring coefficient κ eff . In this way, in order to close lid  106 , a closing force must be applied to lid  106  that is resisted by torsion spring T (increasing the potential energy U stored in torsion spring T) until keeper  102  is retained, or latched into place by latch  104 . The potential energy U stored in torsion spring T by the force applied to close lid  106  can be expressed as equation (1): 
     
       
         
           
             
               
                 
                   U 
                   = 
                   
                     
                       2 
                       2 
                     
                      
                     κ 
                      
                     
                         
                     
                      
                     
                       θ 
                       2 
                     
                   
                 
               
               
                 
                   equation 
                    
                   
                       
                   
                    
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
     
     where κ is torsion spring constant and θ is angle of twist from equilibrium required to maintain lid  104  in the closed state. In this way, restoring force F r  (and the overall latching characteristics of latch system  100 ) can be seen to be tightly coupled to the material nature and the geometry of lid  106 . It is this tight coupling of the characteristics of latch system  100  and the geometry and material of housing  108  that can limit a product designer&#39;s ability to provide a finished product with a design that is both aesthetically pleasing and functionally efficient. 
     Although latch designs generally work well, in many instances it would be desirable to provide an integrated latch system having characteristics that do not unduly burden a product design and that is at least compact in nature and aesthetically pleasing in both the latched and unlatched state. 
     SUMMARY OF THE INVENTION 
     An integrated latch system is described. The integrated latch system including at least a latch, a keeper, and a discrete actuator. In a closed state, the actuator is in direct contact with the keeper and applies a first force to the keeper, the latch applies a second force to the keeper, the first and the second force cooperating to engage the latch and the keeper. In transitioning from the closed state to the open state, a releasing force is applied to the latch, the latch moving at least a predetermined distance in response to the releasing force thereby causing the latch and the keeper to disengage. The actuator applies an ejection force onto the keeper and the keeper moves to an open position in response to the ejection force. 
     In one embodiment, a method of selectively securing access to a recess in a housing by opening and closing a cover. The method can be carried out by performing at least the following operations. Providing a latch system, the latch system including at least a latch, a keeper coupled to the covering, and a discrete actuator in direct physical contact with the keeper. The latch and the actuator cooperate to maintain the latch system in a closed state and cooperate to transition the latch system to an open state. 
     A computer is disclosed. The computer includes at least a housing forming an enclosure suitably configured to accommodate computer components, a cover pivotably attached to the housing in proximity to the enclosure, wherein in an open state, the cover allows a user access to the enclosure and wherein in a closed state, the cover prevents user access to the enclosure, and an integrated latch system operable coupled to the housing and the cover that allows the user to open and close the cover. The integrated latch system includes a latch, a keeper coupled to the cover, and a discrete actuator. In a closed state, the actuator is in direct contact with the keeper and applies a first force to the keeper, the latch applies a second force to the keeper, the first and the second force cooperate to engage the latch and the keeper. In transitioning from the closed state to the open state, a releasing force is applied to the latch, the latch moving at least a predetermined distance in response to the releasing force thereby causing the latch and the keeper to disengage, the actuator applying an ejection force onto the keeper, and the keeper moving to an open position in response to the ejection force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The described embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
         FIG. 1  shows a conventional latch system. 
         FIG. 2  shows a state diagram of a latch system in accordance with the described embodiments. 
         FIG. 3A  shows an integrated latch system in accordance with the described embodiments in a closed state. 
         FIG. 3B  shows the integrated latch system of  FIG. 3A  in an unlatched, closed state. 
         FIG. 4  shows the integrated latch system of  FIG. 3B  in an unlatch and open state. 
         FIG. 5  shows a side and top view of the integrated latch system of  FIG. 4 . 
         FIG. 6  shows a flowchart detailing a process in accordance with the described embodiments. 
         FIGS. 7-9  show various specific embodiments of the integrated latch system. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to selected embodiments an example of which is illustrated in the accompanying drawings. While this application describes several embodiments, it will be understood that it is not intended that there be a preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the appended claims. 
     A number of embodiments of an integrated, low profile latch system are discussed. Generally speaking, as shown by state diagram  200  in  FIG. 2 , the latch system can be in a closed state or an open state at the discretion of a user. In the closed state ( 202 ), a discrete actuator co-operates with a latch that directly engages a keeper. The discrete actuator directly applying a retention force to the keeper in the closed state, the keeper being engaged with the latch. The latch applying a restraining force on the keeper that overcomes the retention force to maintain the latch system in the closed state. In transitioning to the open state from the closed state, a releasing force can be applied to the latch ( 204 ), if the releasing force is sufficient to overcome the retention force ( 206 ), the keeper disengages from the latch and the system transitions to the open state ( 208 ), otherwise, the latch system remains in the closed state. In the open state, the (dis-engaged) keeper is acted upon by an ejection force provided by the discrete actuator. The ejection force compelling the keeper to transition to an open position consistent with the open state of the latch system. In transitioning to the closed state from the open state, a closing force is applied to the keeper ( 210 ). If the closing force is sufficient to overcome a minimum energy threshold of the discrete actuator ( 212 ), then the latch system transitions to the closed state, otherwise it remains in the open state. 
     In more specific embodiments, an integrated latch system is described. The integrated latch system can be compact in size and present a substantially uniform appearance to a user in both a latched (closed) and an unlatched (open) state. The integrated latch system can have well defined latching characteristics independent of the material properties or the design of the housing. The integrated latch system can include at least a keeper assembly in direct contact with a discrete actuator. The keeper assembly can include a keeper and a lid, or cover, used to conceal a recess in the housing. The recess can be used to temporarily retain components such as a battery. In a latched state, the lid can cover the recess. The discrete actuator can apply a well defined retention force directly on the keeper. The keeper, in turn, can directly engage the latching mechanism that, in turn, can apply a restraining force to the keeper. The restraining force can constrain the keeper from moving in relation to the latching mechanism and the housing. In order to transition to the unlatched state and uncover the recess, a releasing force that overcomes the restraining force can be applied to the latching mechanism. The releasing force can cause the latching mechanism to dis-engage the keeper. In one embodiment the releasing force causes the latching mechanism to translate in the direction of the applied releasing force at least a pre-defined distance. The pre-defined distance being at least sufficient to cause the latching mechanism and the keeper to physically dis-engage. The actuator can apply an ejection force to the dis-engaged keeper that can compel the keeper to move to an open position in relation to latching mechanism and the housing. 
     Embodiments of the invention are discussed below with reference to  FIGS. 3-9 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes as the invention extends beyond these limited embodiments. 
       FIG. 3A  shows integrated latch system  300  in accordance with the described embodiments. When latch system  300  is in the latched state, lid  302  can be secured to housing  304  thereby covering recess  306 . Latch system  300  generally includes keeper  308  and lid  302 . In the described embodiment, keeper  308  and lid  302  are integrally formed. Keeper  308  can be in direct contact with actuator  310 . Actuator  310  can provide retention force F 1  directly to keeper  308 . Retention force F 1  can be provided by any number of different force producing mechanisms. In one embodiment retention force F 1  can be provided by a spring mechanism, such as a compression spring. In other embodiment, retention force F 1  can be provided by an electromechanical mechanism. In any case, retention force F 1  can be provided in any manner deemed appropriate and suitable for the product at hand. In a latched state, keeper  308  and latch  312  can be engaged. In the described embodiment, keeper  308  can be in direct physical contact with latch  312 . Latch  312  can exert restraining force F 2  on keeper  308 . In a stable, closed configuration restraining force F 2  can overcome retention force F 1  such that the keeper remains engaged with latch  312 . In this way, lid  302  can remain in a closed position preventing access to recess  304 . 
     Latch  312  can be received by latch receiving area  314  that can be formed as part of housing  304 . Latch  312  and latch receiving area  314  can be cooperatively positioned and sized so that when lid  302  is closed, both latch  312  and latch receiving area  314  can engage with one another thus securing lid  302  to housing  304 . As shown, latch  312  can protrude from a top portion of housing  304  and latch receiving area  314  can be located in a portion of housing  304  suitable for receiving latch  312  when latch  312  is horizontally translated at least distance “d” to disengage keeper  308 . Latch  312  and latch receiving area  314  can be widely varied. For example, latch  312  may be movably affixed to housing  304 . In this way, as shown in  FIG. 3B , a user can indirectly open lid  302  by applying releasing force F 2  that can cause latch  312  to translate approximately distance “d” into latch receiving area  314 . In the described embodiment, latch system  300  can be configured such that latch  312  and keeper  308  can disengage only when latch  312  moves at least distance “d” into receiving area  314 . Once keeper and latch  312  disengage, actuator  310  can exert ejecting force F 3  on keeper  308 . Ejecting force F 3  can compel keeper  308  to move in relation to latch  312  and housing  304  to open position as shown in  FIG. 4 . In this way, lid  302  can move and uncover recess  306 . As shown in  FIG. 5  (with lid  302  removed for clarity), actuator  310  and latch  312  can form what appears to be from a top view a substantially uniform extension of housing  304  once keeper  308  and latch  312  disengage. In this way, the substantially uniform appearance can enhance the aesthetic look and feel of housing  304  since a user&#39;s eye is not attracted to nor distracted by latch system  300 . 
     As discussed above, actuator  310  can take many forms. In some embodiments, a spring mechanism along the lines of a compression spring can be incorporated in or coupled with actuator  310 . In so doing, when a user wishes to close lid  302 , the user applies a closing force F close  to lid  302  that, in turn, forces keeper  308  to move actuator  310  distance “x”. In this way, potential energy (U) can then stored in the compression spring of actuator  310  according to equation (2) 
         U= 1/2 kx   2   eq (2)
         where k: is spring coefficient of the compression spring,
           x: is the displacement of actuator.
 
Potential energy U can be imparted to lid  302  when keeper  308  and latch  312  are subsequently disengaged.
   
               

     Clearly, operating characteristics of latch system  300  are only dependent upon the properties of actuator  310 , namely, the spring coefficient k. In contrast, conventional latch system  100  exhibits behavior that is dependent on both the material used to form the lid (k eff ) and the design of the housing (the allowable θ). By providing a discrete actuator having its own characteristics that can be established with little or no consideration of the material used to fabricate housing  302 , there can be little or no coupling between the properties of latch system  300  and that of housing  304 . In this way, the product designer is given substantially greater latitude in the industrial design aspects of any products that utilize latch system  300 . 
       FIG. 6  shows a flowchart detailing process  600  for controlling a state of an integrated latch system in accordance with the described embodiments. Process  600  can be carried out by performing at least the following operations. In a closed state at  602 , directly applying a first force to a keeper by a discrete actuator, the keeper being in direct contact with and restrained by a latch. The latch applying a second force on the keeper that overcomes the first force directly applied by the actuator. In order to transition from the closed state to an open state, applying a releasing force to the latch at  604 . If, at  606 , it is determined that the releasing force does not overcome the first force, then the integrated latch system remains in the closed state, otherwise the integrated latch system transitions to the open state by the keeper disengaging from the latch at  608  and moving under an ejection force provided by the discrete actuator to an open position relative to the actuator and the latch at  610 . In transitioning to the closed state from the open state, applying a closing force to the keeper at  612 . If it is determined at  614  that the closing force imparts more than a first threshold of potential energy to the discrete actuator, then at  616  the latch system transitions to the closed state, otherwise it remains in the open state. 
       FIGS. 7-9  illustrates various views, both internal and external, of representative integrated latch system in accordance with the described embodiments.  FIGS. 7 and 8  show perspective views of latch system  700  in an open state and a closed state, respectively. Latch system  700  can include latch  702 , keeper  704 , latch receiving area  706  formed from housing  708 . As shown in  FIG. 7 , latch  702  can engage keeper  704  in a latched state. Latch receiving area  706  being co-operatively formed with housing  708  can allow latch  702  to translate a distance “d” sufficient to allow keeper  704  and latch  702  to disengage in transitioning to an unlatched state as shown in  FIG. 8 . It should be noted that as viewed from the top, latch system  700  in  FIG. 8  appears to be uniform in nature. For example, reference line  802  would appear to an observer to be substantially unbroken from point A to point B and therefore would substantially blend in with housing  708  if the particular product design determined that to be desirable. 
       FIG. 9  shows integrated latch system  900  suitable for latching/unlatching a door found on, for example, a computer. In a closed, or latched state, spring based actuator also referred to as ejector  902  applies retention force on keeper  904 . Keeper  904  being integrally formed with door  906 . Latch  908  applies restraining force directly onto keeper  904 . In order to transition to an open state, a releasing force is applied to latch  908  that can overcome the restraining force causing latch  908  to laterally translate toward and into enclosure  910  at least a distance d. The distance d being sufficient to at least disengage latch  908  and keeper  904 . Enclosure  910  being configured to accommodate at least latch  908  and ejector  902 . Latch  908  and keeper  904  disengage and ejector  902  applies an ejecting force directly onto keeper  904 . The ejecting force causing keeper  904  and door  906  to move to an open position relative to housing  912 . In order to transition from the open state to the closed state, a closing force is applied to keeper  904  (or door  906 ) causing the potential energy of the spring associated with ejector  902  to increase. If the increase in potential energy is greater than a first threshold, then latch system  900  transitions to the closed state, otherwise latch system  900  remains in the open state. 
     While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents, which fall within the scope of this invention. For example, although the invention is primarily directed at a recess found in portable electronic devices, the invention can be well suited for other applications.