Abstract:
Embodiments of the invention show a tablet cover that folds to provide a stand for the tablet. A friction hinge between two sections of the tablet cover provides sufficient friction to maintain the stand at the desired angle. In order to allow the cover to be easily flattened after use, a release mechanism is provided in the friction hinge.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to U.S. Provisional Application Ser. No. 62/077,135, filed Nov. 7, 2014 and entitled “Adjustable Protective Cover for an Input Device,” the contents of which are incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to cases or covers for input devices, and in particular in embodiments to cases or covers that fold to provide a stand for a tablet computer. 
         [0003]    A variety of designs have been developed for such cases. For example, Speculative Product Design US Published Application No. 20120285859 shows a tablet cover with a friction hinge at an edge of the cover. US Published Application No. 20130313142 shows a tablet cover with an intermediate hinge on an arm of the cover. Other examples of a case that folds to form a tablet stand include InCase Designs US Published Application No. 20130075281, Speculative Product Design US Published Application No. 20130241381, and Marware US Published Application No. 20140291174. 
         [0004]    There is a need for a case/stand that is easy for a user to manipulate, and which is sturdy enough to allow typing on a supported tablet without the tablet bouncing back and forth. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    Embodiments of the invention show a device cover that folds to provide a stand for the device (e.g., a tablet computer). A friction hinge between two sections of the cover provides sufficient friction to maintain the stand at the desired angle. In order to allow the cover, with a hinge in the middle, to be easily flattened after use, a release mechanism or detent is provided in the friction hinge. 
         [0006]    In one embodiment, the release mechanism is a non-circular portion on the hinge axle which engages a similar non-circular surface on a hinge sleeve. In one embodiment, the non-circular portions are flat, and engage each other when the first and second top cover sections are at an angle of 150 degrees or greater, or around 170 degrees or greater. 
         [0007]    In one embodiment, the top cover folds 180 degrees around an edge to move from covering the table display to the back of the tablet. The upper portion of the cover then folds down around the friction hinge to create a stand. The lower portion of the cover is up against the bottom surface of the tablet, where a keyboard display may appear on the tablet. There are magnets in this top cover that engage the bottom of the case to hold it firmly in place during typing or touch input. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a diagram illustrating a cover according to an embodiment of the invention, showing it enclosing a tablet. 
           [0009]      FIG. 2  is a diagram illustrating a cover according to an embodiment of the invention, showing it folded to act as a stand. 
           [0010]      FIG. 3  is a diagram illustrating a top cover according to an embodiment of the invention, showing the hinges. 
           [0011]      FIG. 4  is a diagram illustrating an exploded view of a hinge structure according to an embodiment of the invention. 
           [0012]      FIG. 5  is a diagram illustrating a disassembled hinge according to an embodiment of the invention, showing the hinge sleeve and axle. 
           [0013]      FIG. 6  is a diagram illustrating an assembled hinge according to an embodiment of the invention. 
           [0014]      FIG. 7  is a diagram illustrating a partially disassembled hinge according to an embodiment of the invention, showing the flat portions of the hinge sleeve and axle. 
           [0015]      FIG. 8  is a diagram illustrating the partially assembled hinge of  FIG. 7 , showing the hinge partially rotated. 
           [0016]      FIG. 9  is a diagram illustrating a hinge plate according to an embodiment of the invention. 
           [0017]      FIG. 10  is a diagram illustrating a cross-section of the hinge axle according to an embodiment of the invention, showing opposite flat portions. 
           [0018]      FIG. 11A  is a diagram illustrating aspects for a sequence of opening a cover according to an embodiment of the invention and folding it into a stand position. 
           [0019]      FIG. 11B  is a diagram illustrating aspects for a sequence of opening a cover according to an embodiment of the invention and folding it into a stand position. 
           [0020]      FIG. 11C  is a diagram illustrating aspects for a sequence of opening a cover according to an embodiment of the invention and folding it into a stand position. 
           [0021]      FIG. 11D  is a diagram illustrating aspects for a sequence of opening a cover according to an embodiment of the invention and folding it into a stand position. 
           [0022]      FIG. 11E  is a diagram illustrating aspects for a sequence of opening a cover according to an embodiment of the invention and folding it into a stand position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]      FIG. 1  is a diagram illustrating a case according to an embodiment of the invention, showing it enclosing a tablet. The case has a top cover  10 , a bottom cover  12  and a flexible side hinge  14 . The top cover  10  has two top sections  16  and  18  joined along a hinged axis  20 . The top cover sections  16  and  18  are plastic plates covered by an outer fabric or textile. A magnet  22 , shown in phantom, holds the top cover  10  closed against an enclosed tablet. Magnets  24  on top cover section  18 , shown in phantom, provide an upward magnetic force used in the folded, stand position as illustrated in  FIG. 2 . Magnets  22  and  24  are internal to the top cover, and thus shown in phantom. 
         [0024]      FIG. 2  is a diagram illustrating the case of  FIG. 1 , showing it folded to act as a stand. The top cover is shown after it has been rotated 180° around hinge  14  so that section  18  of the top cover is adjacent the underside bottom of the case. The bottom  25  of the case is covered with polyurethane and includes a resin bumper  26  around the edges supporting and enclosing a tablet  28 . Top section  16  is bent around hinge axis  20  to form a stand. Magnets  24  in section  18  are adjacent a corresponding magnetic element  30  in the case bottom  25  to provide a holding force. This holding force helps firmly hold the bottom of the tablet  28  against the stand, providing stability during a typing operation on a soft keyboard which appears at the bottom of the display of tablet  28 . The magnets also allow a user to pick-up the cover and move/reposition it, without the cover releasing from the back of the tablet. 
         [0025]      FIG. 3  is a diagram illustrating the top cover of  FIG. 1 , without the textile cover, showing the hinges. Plastic supports  32  and  34  are shown forming top cover sections  16  and  18 , respectively, without the textile covers. Two metal hinge assemblies  36  and  38  are shown, attached to the plastic supports  32  and  34 . 
         [0026]      FIG. 4  is a diagram illustrating an exploded view of a hinge assembly of  FIG. 3 . Hinge assembly  36  includes structures  40  and  42  in plastic supports  32  and  34  with depressions and holes for accepting the hinge, hinge cover, and fasteners. A hinge  44  is mounted in structures  40  and  42 . Aluminum covers  46  and  48  are mounted over hinge  44 . Screws, not shown, fasten the assembly together through the screw holes. 
         [0027]      FIG. 5  is a diagram illustrating a disassembled hinge according to an embodiment of the invention, showing the hinge sleeve and axle. Hinge  44  includes a metal plate  50  having a sleeve  52  formed by folding an extension of the metal plate. A second metal plate  54  includes a smaller sleeve  56 . An axle  58  is inserted into the sleeves and is fastened to plate  54  using rivets  60  through holes  62  in axle  58  and holes  64  in plate  54 . 
         [0028]      FIG. 6  is a diagram illustrating an assembled hinge according to the embodiment of  FIG. 5 .  FIG. 6  shows the assembled structure with plate  50  joined with plate  54  using axle  58 . Screw holes  66  are shown for fastening the structure to the plastic support shown in  FIG. 4 . Also shown are positioning features  68  for engaging with similar features in the plastic supports. 
         [0029]      FIG. 7  is a diagram illustrating a partially disassembled hinge according to an embodiment of the invention, showing the flat portions of the hinge sleeve and axle.  FIG. 7  shows axle  58  having a flat area  70  along its top, which engages with a flat portion  72  in hinge sleeve  52 . When the flat areas are engaged with each other, the hinge assembly is held in a flat position. As the axle turns, and the flat portion comes in contact with a circular inside portion of sleeve  52 , there is friction which provides the friction hinge force. As the axle is turned back towards the flat portion  72  of sleeve  52 , when it gets within a small number of degrees, such as 10°, it will snap into position to be aligned with flat area  52 , releasing the friction. This provides a release mechanism or detent, and makes it easy to arrange the hinge plates, and thus the two sections of the cover, in a completely flat position. 
         [0030]      FIG. 8  is a diagram illustrating the partially assembled hinge of  FIG. 7 , showing the hinge partially rotated. In the position shown in  FIG. 8 , flat portion  72  of sleeve  52  has rotated away from flat portion  70  of hinge axle  58 , thus providing a friction holding force. 
         [0031]      FIG. 9  is a diagram illustrating the hinge plate with two opposed flat portions.  FIG. 9  shows a hinge plate  80  with a sleeve  82  having a top flat portion  84  with a corresponding, opposite flat portion  86 . These two, opposite flat portions engage flat portions on the top and bottom of the axle, which reinforces the release force and the stability by having applied both the top and bottom simultaneously. 
         [0032]      FIG. 10  is a diagram illustrating a cross-section of the hinge axle according to an embodiment of the invention, showing opposite flat portions. Axle  58  includes a top flat portion  90  and bottom flat portion  92 . These engage the corresponding flat portions  84  and  86  of the hinge sleeve shown in  FIG. 9 . In between flat portions  90  and  92 , the axle is circular, such as in a position  94 , to correspondingly engage with the circular inside portions of the hinge sleeve. 
         [0033]      FIGS. 11A-E  illustrate a sequence of opening a cover according to an embodiment of the invention and folding it into a stand position.  FIG. 11A  shows the top cover  10  with sections  16  and  18  and a side hinge  14  as shown in  FIG. 1 .  FIG. 11B  shows the top cover starting to be folded away from the display  27  of tablet  28 .  FIG. 11C  shows the top cover folded nearly 360° so that is close to the back of the tablet, on the opposite side from display  27 . As illustrated by arrow  100 , the next step is to fold top portion  16  around axis  20 . 
         [0034]      FIG. 11D  shows top cover section  16  folded down at an angle to support the tablet against section  18  of the top cover.  FIG. 11E  shows sections  16  and  18  at a wider angle, allowing the display  27  of the tablet to be angled farther downward, closer to a flat position. 
         [0035]    Various other embodiments are possible within the scope of the appended claims. For example, instead of flat portions on the axle and sleeve, different non-circular shapes could be used, such as a pyramid, saw-tooth, non-circular curve, etc. The hinge axle and the hinge sleeve could have additional non-circular portions for supporting the hinge assembly in a released or detent position at angles other than a flat, 180° angle. For example, two additional flat portions could be added to allow the structure to snap into and be stable at a desired, optimum viewing angle. Alternately, one hinge assembly can have up and down opposite flat structures, while the second hinge assembly can have the flat structures at the desired angle. In another embodiment, more than two detent or release angles are possible. 
         [0036]    The fabric covering the top cover on the outside is ideally a fabric which can stretch and extend as the two sections are bent to form the stand. Conversely, a fabric or material on the inner surface of the top cover can have properties of easily compressing when folded and then returning to its original shape when laid flat again. 
         [0037]    In one embodiment, the axis of the top cover is located somewhere between the middle of the cover and the bottom part of the cover. Having section  16  wider than section  18  allows section  16  to bend down to the support surface and hold the tablet at a variety of angles. Section  18  is wide enough to provide support against at least most of the virtual keyboard on the tablet display. 
         [0038]    In one embodiment, the frictional force is designed to be around 2×3.6++/−0.4 kg/m, to provide sufficient standing force to hold the position of the tablet, while being a small enough force to allow a user to unfold and fold the cover without undue effort.