Abstract:
Systems and methods for assembling a mobile cellular device do not require screws or adhesives, allowing for more efficient and less wasteful rework of the device when needed. In an embodiment, one or more fixed lock elements are attached to one a screen assembly of the device (or the device housing) and a locking shaft is retained in the housing (or the screen assembly). The locking shaft includes blocking sections that block passage of the lock elements, and non-blocking sections that permit passage of at least part of each lock element. In this way, when the screen assembly is mated to the housing, each lock element aligns with and at least partially passes over one of the non-blocking sections, such that when the locking shaft is slid axially, the lock elements align with and are retained by the blocking sections.

Description:
TECHNICAL FIELD 
     The present disclosure is related generally to mobile device structure and construction, and, more particularly, to a system and method for securing one part of such a device to another. 
     BACKGROUND 
     Mobile device construction typically employs one or both of screws and adhesives to lock major structures together, e.g., housings, printed circuit boards (PCBs), and display assemblies. When reworking assemblies in which adhesives have been used, it is generally necessary to apply heat or chemicals to breakdown the adhesives in order to pry the assemblies apart. 
     In assemblies in which screws have been used to hold parts together, these parts may be disassembled once or twice generally before further manipulation results in stripped thread bosses. As with adhered assemblies, the reworking of screwed assemblies requires tools. In addition screws typically need to be covered after assembly so that they are not visible or accessible to the end consumer. 
     The present disclosure is directed to a system that can eliminate certain shortcomings of present systems. However, any such benefit is not a limitation on the scope of the disclosed principles, or of the attached claims, except to the extent expressly noted in the claims. Additionally, the discussion of technology in this Background section is reflective of the inventors&#39; own observations, considerations, and thoughts, and is in no way intended to accurately catalog or comprehensively summarize any prior art reference or practice. As such, the inventors expressly disclaim this Background section as admitted or assumed prior art. Moreover, the identification herein of desirable courses of action reflects the inventors&#39; own observations and ideas, and should not be assumed to indicate an art-recognized desirability. 
     SUMMARY 
     In an embodiment of the disclosed principles, a mobile cellular device is provided having a housing and a screen assembly. One or more locking bars are affixed to one of the housing and the screen assembly, and a locking shaft is retained in the other of the housing and the screen assembly. The locking rod includes one or more large diameter sections and one or more smaller diameter sections, such that when the screen assembly is mated to the housing, the one or more locking bars align with and pass over respective one or more smaller diameter sections. When the locking rod is slid axially, the one or more locking bars align with and are retained respective one or more large diameter sections. 
     In another embodiment, the mobile cellular device includes one or more locks affixed to one of the housing and the screen assembly and a locking shaft retained in the other of the housing and the screen assembly. The locking shaft includes one or more blocking sections that block passage of respective ones of the locks, and one or more non-blocking sections that permit passage of at least a portion of respective ones of the locks. In this way, when the screen assembly is mated to the housing, each of the locks aligns with and at least partially passes over a respective one of the non-blocking sections, and when the locking shaft is slid axially, the locks align with and are retained by respective ones of the blocking sections. 
     In a method of assembling a mobile cellular device in accordance with yet another embodiment of the disclosed principles, a resilient gasket is placed between the top half and the bottom half of the device, and a compressive force is applied, compressing the top half and a bottom half together. This compresses the resilient gasket and allows a sliding a rod within the bottom to be slid into an interference fit relative to a protrusion extending from the top half. Releasing the compressive force causes the resilient gasket to at least partially rebound and traps the rod and protrusion together. 
     Other features and embodiments of the disclosed principles will be appreciated from the detailed description herein, including the figures. It will be appreciated that this document describes example embodiments and does not limit the claims to such embodiments. Rather those of skill in the art will appreciate that embodiments and features other than those shown may be used without departing from the scope of the disclosed principles. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       While the appended claims set forth the features of the present techniques with particularity, these techniques, together with their objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a side view of a two part device within which embodiments of the disclosed principles may be implemented; 
         FIG. 2  is a front view of a two part device within which embodiments of the disclosed principles may be implemented; 
         FIG. 3  is a partial cross-sectional end view of a device including a locking system in accordance with an embodiment of the disclosed principles; 
         FIG. 4  is a partial cross-sectional side view of a device including a locking system in accordance with an embodiment of the disclosed principles, wherein locking features are aligned; 
         FIG. 5  is a partial cross-sectional side view of a device including a locking system in accordance with an embodiment of the disclosed principles, wherein locking features are aligned and the device halves are compressed together; and 
         FIG. 6  is a partial cross-sectional side view of a device including a locking system in accordance with an embodiment of the disclosed principles, wherein the device halves are compressed together and the locking rod has been slid into a locking position. 
     
    
    
     DETAILED DESCRIPTION 
     As noted above, mobile device construction typically employs screws and adhesives to lock major structures together, e.g., housings, printed circuit boards (PCBs), and display assemblies. When reworking these assemblies where adhesives have been used, heat or chemicals are generally applied to breakdown the adhesives in order to pry the assemblies apart. This process may damage device displays and lenses, as well as cosmetic surfaces. 
     In assemblies wherein screws have been used to hold parts together, these parts may be disassembled once or twice generally before further working strips or compromises screw hole threads in attachment bosses. Moreover, as with adhered assemblies, the reworking of screwed assemblies requires tools and may result in damage to various parts of the device. 
     When damage occurs using either technology, costs are often incurred for replacing or scrapping the affected parts. Moreover, even if rework is performed without damaging any parts of the device, the use of screws and adhesives generally precludes any entity outside of an assembly plant from making changes or additions to the device. Thus, for example, later customization steps, sometimes referred to herein as “postponable steps,” are difficult to perform other than at the place and time of device assembly. 
     To at least partly ameliorate one or more of the issues noted above, an embodiment of the disclosed principles employs a latching rod attachment system to attach an “internals” assembly (e.g., the main display assembly bonded to PCBs, batteries, carriers with cameras and so on) to the device shell or housing. The internals assembly in accordance with this embodiment includes either a sliding lock rod or one or more mating latches, and the device shell includes the other of these two features so as to provide an interlocking attachment via interaction of the sliding lock rod and the mating latches. 
     A resilient gasket or other compressible structure is located at the periphery of the internals assembly, between the internals assembly and the device shell in an embodiment. This gasket seals the internal cavity of the device and also enables assembly and retention as explained more fully below, without adhesives or threaded fasteners such as screws. 
     For assembly, the combined but not yet latched device, including the internals assembly and the device shell, is pressed together, compressing the resilient gasket. This step may be accomplished via a press or other fixture or may be manually executed. The compression of the internals assembly into the shell pushes the locking rod past the mating locking features, and while the device is still compressed, the locking rod is slid into an interference position relative to the mating locking features. In an embodiment, the locking rod includes a permanent magnet at one or both ends thereof, and one or more magnets outside the device are slid along the device to move the locking rod into the interference position. 
     In a further embodiment, the locking rod includes one or more posts, and the external magnets are rotated to rotate the locking rod so that the posts lock into additional interlocking features. At this point in the assembly process, the compression force on the device is released, allowing the internals assembly to move slightly away from the device housing under the force of the gasket, setting the interlocking features. With the locking rod and mating latches engaged, the mobile device is fully secured without requiring the use of adhesives or threaded fasteners to retain the major subassemblies. 
     For the purpose of rework, the assembled device may be re-compressed, e.g., in the same or different fixture, and the magnets rotated and slid in the opposite directions and sequence from their original movements in order to unlock the device. At this point, the entire assembly can be separated easily into its subassemblies with no need to unscrew fasteners or remove adhesives. This allows for convenient and safe rework, e.g., if an assembly error has occurred. 
     For example, the device may need to be reworked if the wrong color housing was used, if a device housing has been found to be scratched, or if any other situation occurs in which the assembled device needs to be taken apart for modification. Using embodiments of the disclosed principles to assemble the device and retain its subassemblies, there is much less risk of damaging any component, including the expensive lens assembly, during any needed disassembly and reassembly. 
     With this overview in mind, and turning now to a more detailed discussion in conjunction with the attached figures,  FIG. 1  is a perspective view of a generic device design. In particular, the illustrated device  100  includes an upper half  101  and a lower half  103  joined at a parting line  105 . It will be appreciated that one half may utilize an inset on the face thereof while the other half may utilized a raised peripheral lip in order to align the subassemblies and prevent lateral movement of either portion relative to the other in the assembled device. 
     In a typical construction, the halves  101 ,  103  would be retained by screws or adhesive. Although not visible in the illustrated view, it will be appreciated that the lower half  103  is essentially a shell or bucket that surrounds components that are part of the top half  101 . The top half  101  includes primarily a display and associated components (not shown) such as batteries, circuitry, PCBs, framing and structural components. 
       FIG. 2  shows a front schematic view of the device  100  of  FIG. 1 . In this view, the external surface of the top half  101  can be seen. A display screen  200  is shown on the front surface. Although the illustrated screen  200  covers essentially all of the outward-facing external surface of the top half  101 , it is contemplated that a smaller portion of the surface may instead be covered and that other features may be present on the illustrated surface. Such other features may include speakers, button and so on. 
     During rework of the device  100 , it would typically be necessary to separate the upper half  101  of the device  100  from the lower half  103  of the device  100  in order to replace one or the other or to replace or repair an internal component. As such, if the halves  101 ,  103  are held together by an adhesive or by threaded fasteners, then these must be removed or unscrewed to allow access. 
     However, in an embodiment of the disclosed principles, a device such as device  100  of  FIG. 1  is held together in its assembled configuration without the use of either adhesives or threaded fasteners. The disclosed fastening system, an embodiment of which is shown in axial cross-section in  FIG. 3 , includes two portions that interlock to retain the device  100  in the assembled configuration. The schematic illustration of  FIG. 3  shows these two portions without the surrounding device components for clarity. 
     The first portion of the locking system  300  comprises one or more locking bars  301 , which may be attached to a locking bar rail  307  or may be directly attached to a device half such as the top half  101 . The second portion of the locking system  300  comprises a locking rod  309  secured to the other half of the device  100  such that it may slide along its axis and turn about its axis relative to the associated device half, but cannot move substantially in any other directions. The locking rod  309  has an outer surface  303  and includes one or more waisted sections  305 . In an embodiment, the locking rod  309  also includes a permanent magnet, e.g., on one rod end or the other (not shown in  FIG. 3 ). 
     In an embodiment of the disclosed principles, a “ski boot” type latch is employed to secure the opposite edge of each half  101 ,  103 . This latch includes one or more tabs  313  and one or more corresponding catches or slots  315  on the opposite half  103 . It will be appreciated that the illustrated features in  FIG. 3  are not drawn to scale, and may be much smaller or larger than shown, relative to the dimensions of other parts such as the top and bottom device halves  101 ,  103 . 
     A side view of the locking rod  309  and the locking bars  301  is shown in  FIG. 4 . In this view, the permanent magnet  401  mentioned above can be seen. In addition, a rod end latch  403  is shown. This feature is configured to snap upward and retain the locking rod  309  in the locked state once this state is reached as will be discussed more fully below. 
     When the tabs  313  of the latch system are engaged in the corresponding openings  315  on the opposite half  103 , the one or more locking bars  301  are vertically aligned with the one or more waisted sections  305  of the locking rod  309 . In this way, when the device  100  is closed by swinging the two halves  101 ,  103  together, the one or more locking bars  301  pass over the one or more waisted sections  305  of the locking rod  309 , allowing the halves  101 ,  103  to meet as shown in  FIG. 5 . 
     In this configuration, the one or more locking bars  301  prevent the locking rod  309  from sliding along its axis due to interference with the larger diameter sections adjacent each waisted section  305 ,  313 . However, if the device halves  101 ,  103  are now compressed further together, the lower portions of the one or more locking bars  301  drop below the diameter of the larger diameter sections  305  of the locking rod  309 . 
     At this point, the locking rod  309  can be slid along its axis by an applied force, e.g., via an external magnet interacting with the magnet  401  on the locking rod  309 . This configuration is shown in the illustration of  FIG. 6 . As can be seen, the locking rod  309  has moved to the left in the illustrated perspective, causing the larger diameter sections  305  of the locking rod  309  to interact with the inwardly bent ends of locking bars  301 . 
     When the compression force on the device  100  is released, the two halves  101 ,  103  are locked together via the interference of the locking bars  301  and the larger diameter sections  303  of the locking rod  309  as shown in  FIG. 5 . In an embodiment, an elastomeric gasket  317  ( FIG. 3 ) is situated between the halves  101 ,  103  prior to assembly. This gasket  317  provides a rebounding force, against which the two halves  101 ,  103  are compressed and via which the components are held in the locked position when the compression force is released. It will be appreciated that other rebounding mechanisms such as springs may be used without departing from the disclosed principles. 
     Because the force used to move the rod  309  into the locked position is supplied magnetically rather than by direct contact, the moving and interfering parts are low friction parts in an embodiment of the disclosed principles. The low friction characteristic may be a result of the use of low friction materials, or may be accomplished by highly polishing metal surfaces. The sources of friction to be minimized in this embodiment include primarily friction due to tolerance and rod-to-feature alignment. 
     Thus, in a further embodiment, oversized through features are used that tighten on the release of compression. To ameliorate slight misalignment of features, and hence binding, lead in surfaces may be used as well. Further, although the disclosed embodiments to this point utilize a locking rod, it will be appreciated that other structures are apparent from this disclosure. For example, two rods may be used, with one located on each side of the device  100 . 
     Although the illustrated locking system uses a sliding rod that is maintained in the locked position by a lifting latch, it will be appreciated that other means for maintaining the position of the rod may be used. For example, in an embodiment, the locking rod  309  includes one or more studs or outcrops that lock into the device structure and prevent the rod from sliding. In a further embodiment, the studs or outcrops are locked into the device structure via a partial rotation of the rod  309 . 
     In another embodiment, a rail lock is used in lieu of or in addition to a rod lock. This embodiment is similar to the locking rod system, except that the rod, which may be on either half, is replaced with a rail. The rail is free to slide axially during assembly but may not rotate. The rail will also typically require less device volume for use. Herein, the term locking shaft refers to an elongated structure that is either a rod or a rail. 
     Although the embodiments described thus far utilize magnetic force to actuate the locking rod or rail, it will be appreciated that it is not required to have a permanent magnet on the rod or rail for all embodiments. Indeed, in environments where a permanent magnet would otherwise cause problems such, as by saturating of the magnetic field to other metal parts in the phone, the rod magnet may be omitted. In this embodiment, the rod or rail is made of or includes a material that is not magnetized but is simply magnetically responsive. For example, the rod or rail may be or contain iron or other magnetically responsive substance. In an embodiment, the actuation field is set so as to not permanently cause substantial magnetization in the rod or rail. The term “lock” may be used herein to encompass a structure that is either a locking bar that locks to a locking shaft (rail or rod) or another structure (e.g., a stud, rail, inverted top hat, etc.) that locks to the locking shaft (rod or rail). 
     As noted above, a compression fixture having a magnet for actuation may be used. In this embodiment, the magnet may be either a permanent magnet or an electromagnet (or, if desired, an electropermanent magnet). Of these, an electromagnet would allow for use of the same fixture to both lock and unlock the rod, since the polarity could be easily reversed. 
     While there are other application scenarios for the illustrated locking system and process, this document will not attempt to catalog all such uses. Those of skill in the art will appreciate that there are many possible embodiments to which the principles of the present disclosure may be applied. The embodiments described herein with respect to the drawing figures are meant to be illustrative only and should not be taken as limiting the scope of the claims. Therefore, the techniques as described herein contemplate all such embodiments as may come within the scope of the following claims and equivalents thereof.