PATENT DOCUMENT

Publication Number: US-11079807-B1
Application Number: US-201816053693-A
Country: US
Kind Code: B1

Title: Friction roller hinge for electronic devices and method for making roller and spacer elements

Abstract:
A hinge assembly is disclosed. The hinge assembly may include roller elements and spacer elements positioned between adjacent roller elements. The hinge assembly couples with two housing parts, and allows movement of the housing parts with respect to one another. The roller elements synchronously rotate along surfaces of the spacer elements during rotation of one of the housing parts. Also, in order to maintain engagement between the roller elements and the spacer elements, a strap may extend through openings of the roller elements and the spacer elements. Further, the strap may provide the hinge assembly with a desired stiffness. For example, when the first housing part ceases rotational movement, the strap may cause the first housing part to maintain its position relative to the second housing part. Also, the hinge assembly may include a tensioning element coupled to the strap in order to provide tension to the strap.

Claims:
What is claimed is: 
     
       1. A laptop computing device, comprising:
 a base portion that carries an input mechanism; 
 a display housing that carries a display that is controlled by the input mechanism, wherein the display housing is rotatable from an open position to a closed position with respect to the base portion; 
 a hinge assembly coupled to the display housing and the base portion, the hinge assembly comprising:
 a first cylindrical roller element comprising a first opening, 
 a second cylindrical roller element comprising a second opening, and 
 a spacer element comprising:
 a first concave surface engaged with the first roller cylindrical element, 
 a second concave surface engaged with the second cylindrical roller element, 
 a first protrusion extending from the first concave surface and located in the first opening, and 
 a second protrusion extending from the second concave surface and located in the second opening; and 
 
 a strap coupled to the display housing and the base portion and extending through the first roller element, the second roller element, and the spacer element, the strap providing a stiffness such that a transition from the open position to the closed position causes synchronous motion of the first roller element, the second roller element, and the spacer element. 
 
 
     
     
       2. The laptop computing device of  claim 1 , wherein the hinge assembly provides a mechanical stop defined by the strap being pinched between i) the first cylindrical roller element and the spacer element, and ii) the second cylindrical roller element and the spacer element. 
     
     
       3. The laptop computing device of  claim 2 , further comprising:
 a third cylindrical roller element; and 
 a second spacer element between the second cylindrical roller element and the third cylindrical roller element, wherein the mechanical stop includes the spacer element in contact with the second spacer element. 
 
     
     
       4. The laptop computing device of  claim 1 , wherein:
 the first opening defines a first internal surface, 
 the second opening defines a second internal surface, and 
 the hinge assembly provides a mechanical stop defined by the first protrusion being engaged with the first internal surface and the second protrusion being engaged with the second internal surface. 
 
     
     
       5. The laptop computing device of  claim 1 , wherein in the closed position, the display housing and the base portion combine to define a circular opening. 
     
     
       6. The laptop computing device of  claim 1 , wherein:
 the input mechanism comprises a keyboard, and 
 the display housing is rotatable from an open position defined by the keyboard uncovered by the display housing to the closed position defined by the input mechanism covered by the display housing. 
 
     
     
       7. The laptop computing device of  claim 1 , further comprising an end piece positioned in the base portion and coupled the strap, wherein the strap includes fibers aligned in a first direction and wherein the end piece includes fibers aligned in a second direction perpendicular to the first direction. 
     
     
       8. The laptop computing device of  claim 6 , further comprising a second strap and a third strap, the second strap and the third strap extending through the first roller element, the second roller element, and the spacer element, wherein:
 the strap defines a first strap, 
 the second strap counterbalances the display housing, and 
 the third strap comprises a flexible circuit that electrically couples the display with a processor carried by the base portion. 
 
     
     
       9. A system, comprising:
 a first housing part; 
 a second housing part that defines an internal volume; 
 a hinge assembly that rotatably couples the first housing part with the second housing part, the hinge assembly comprising:
 a first cylindrical roller element, 
 a second cylindrical roller element, and 
 a spacer element positioned between, and providing a frictional engagement with, the first cylindrical roller element and the second cylindrical roller element, wherein movement of the first housing part with respect to the second housing part causes a synchronous movement of the first cylindrical roller element, the second cylindrical roller element, and the spacer element; and 
 a strap extending through the first roller element, spacer element, and the second roller element; and 
 
 an adjustable tension system coupled to the strap and fully enclosed within the internal volume, the adjustable tension system comprising:
 a strap retention element coupled, and providing a force to, the strap, the force causing the synchronous movement; and 
 a fastener coupled with strap retention element and configured to adjust the force. 
 
 
     
     
       10. The system of  claim 9 , wherein the strap maintains the frictional engagement between the spacer element and the first cylindrical roller element and the second roller cylindrical element during the rotational movement. 
     
     
       11. The system of  claim 9 , wherein the strap comprises:
 a glass fiber; and 
 a flexible material coupled with the glass fiber, wherein when a pulling force is applied to the flexible material, the flexible material stretches and elongates. 
 
     
     
       12. The system of  claim 9 , wherein the first roller cylindrical element comprises an opening through which the strap passes, the opening defined by a flat surface and a curved surface. 
     
     
       13. The system of  claim 9 , wherein the strap allows the hinge assembly to bend in a first direction but limits the hinge assembly to a predetermined angle in a second direction opposite the first direction. 
     
     
       14. A system comprising:
 a first housing part defined by first dimension extending from a first end and a second end opposite the first end; 
 a second housing part rotatably coupled to the first housing part by a first hinge assembly, the first hinge assembly comprising:
 a first cylindrical roller element comprising a first opening, 
 a second cylindrical roller element comprising a first opening, 
 a spacer element comprising:
 a first concave surface frictionally engaged with the first roller cylindrical element, 
 a second concave surface frictionally engaged with the second cylindrical roller element, wherein each of the first cylindrical roller element, the second cylindrical roller element, and the spacer element are defined by a second dimension that extends from the first end to the second end; 
 a first protrusion extending from the first concave surface and positioned in the first opening, and 
 a second protrusion extending from the second concave surface and positioned in the second opening; 
 
 
 a third housing part; and 
 a second hinge assembly coupled to the second housing part and the third housing part, the second hinge assembly allowing rotational movement between the second housing part and the third housing part. 
 
     
     
       15. The system of  claim 14 , wherein the first cylindrical roller element and the second cylindrical roller element provide a synchronous rotational movement from a closed position defined by the first housing part being positioned over the second housing part to an open position defined by the first housing part being rotated away from the second housing part. 
     
     
       16. The system of  claim 14 , wherein the first housing part includes a concave portion that receives the first cylindrical roller element. 
     
     
       17. The system of  claim 14 , wherein the first hinge assembly allows for rotation of the first housing part relative to the second housing part subsequent to the second hinge assembly allowing the second housing part to separate from the third housing part by a predetermined angle, and wherein the first hinge assembly prevents the rotation of the first housing part relative to the second housing part prior to the second housing part separating from the third housing part by the predetermined angle. 
     
     
       18. The system of  claim 14 , wherein the first dimension equals the second dimension. 
     
     
       19. The system of  claim 14 , wherein the first cylindrical roller element comprises at least one convex surface and at least one flat surface. 
     
     
       20. The system of  claim 14 , further comprising:
 a display carried by the first housing part; and 
 a keyboard carried by the second housing part. 
 
     
     
       21. The system of  claim 1 , wherein:
 the first housing part defines a first rectangular housing part, 
 the second housing part defines a second rectangular housing part, and 
 in the closed position the first rectangular housing part is parallel with respect to the second rectangular housing part.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application claims the benefit of U.S. Provisional Application No. 62/541,073, entitled “FRICTION ROLLER HINGE FOR ELECTRONIC DEVICES,” filed Aug. 3, 2017, the content of which is incorporated herein by reference in its entirety for all purposes. 
    
    
     FIELD 
     The following description relates to hinges and hinge assemblies. In particular, the following description relates to hinge assemblies having multiple parts frictional engaged with one another. 
     BACKGROUND 
     Electronic devices, including portable electronic devices, may include two housing parts that are coupled together by a hinge. The hinge allows the housing parts to rotate with respect to each other, thereby allowing the electronic device to open so that a user can interact with the electronic device, or to close and provide a compact system. 
     However, traditional hinges have several drawbacks. For example, some hinges include a torsion bar designed to twist when the electronic device is opened. Over time, the torsion bar can wear down due to stress from several cycles of opening and closing the electronic device. Also, the hinge may be substantially positioned in one or both of the housing parts. As a result, the space provided by the housing part(s) is limited due to space occupied by the hinge. This can lead to fewer or less powerful operational components installed in the electronic device. 
     SUMMARY 
     In one aspect, a laptop computing device is described. The laptop computing device may include a display housing that carries a display. The laptop computing device may further include a base portion that carries an input mechanism that controls the display. The laptop computing device may further include a hinge assembly coupled to the display housing and the base portion. The hinge assembly may allow a closed position defined by the display housing being positioned over the base portion. The hinge assembly may include a first roller element. The hinge assembly may further include a second roller element. The hinge assembly may further include a spacer element positioned between the first roller element and the second roller element. The hinge assembly may further include a strap coupled to the display housing and the base portion and extending through the first roller element, the second roller element, and the spacer element. The strap may provide a stiffness such that a transition from the open position to the closed position causes synchronous motion of the first roller element, the second roller element, and the spacer element. 
     In another aspect, a system is described. The system may include a first housing part. The system may further include a second housing part. The system may further include a hinge assembly that rotatably couples the first housing part with the second housing part. The hinge assembly may include a first roller element. The hinge assembly may further include a second roller element. The hinge assembly may further include a spacer element positioned between, and providing a frictional engagement with, the first roller element and the second roller element. In some embodiments, rotational movement of the first housing part with respect to the second housing part causes a synchronous movement of the first roller element, the second roller element, and the spacer element. 
     In another aspect, a system is described. The system may include a first housing part having a first end and a second end opposite the first end. The system may further include a second housing part rotatably coupled to the first housing part by a hinge assembly. The hinge assembly may include a first roller element. The hinge assembly may further include a second roller element. The hinge assembly may further include a spacer element frictionally engaged with the first roller element and the second roller element. In some embodiments, the first roller element, the second roller element, and the spacer element include a dimension that extends from the first end to the second end. 
     In another aspect, a portable computing device is described. The portable computing device may include a hinge assembly connected to a base portion and a display housing. The hinge assembly may allow movement of the display housing relative to the base portion to define an open position and a closed position different from the open position. The hinge assembly may include a first roller element that includes a first cavity. The hinge assembly may further include a second roller element that includes a second cavity. The hinge assembly may further include a spacer element that engages the first roller element and the second roller element. The spacer element may include a first protrusion positioned in the first cavity and a second protrusion positioned in the second cavity. Also, in some instances, an engagement of the first protrusion and the second protrusion within the first cavity and the second cavity, respectively, limits the movement of the display housing with respect to the base portion to define the open position and the closed position. 
     In another aspect, a portable computing device is described. The portable computing device may include a hinge assembly connected to a base portion and a display housing. The hinge assembly may allow movement of the display housing relative to the base portion to define an open position and a closed position different from the open position. The hinge assembly may include a first roller element that includes a first through hole having a first convex surface. The hinge assembly may further include a second roller element that includes a second through hole having a second convex surface. The hinge assembly may further include a spacer element that includes a third through hole. The spacer element may engage the first roller element and the second roller element. The hinge assembly may further include a strap coupled to the base portion and the display housing. The strap may pass through the first through hole, the second through hole, and the third through hole. In some instances, in the closed position, the strap engages the first convex surface and the second convex surface. 
     In another aspect, a method for assembling a hinge assembly of a portable computing device is described. The portable computing device may include a base portion and a display housing. The method may include providing a roller element that defines a cylindrical body. The roller element may include a through hole having a convex surface. Also, the roller element may further include a cavity. The method may further include providing a spacer element that includes a second through hole. The spacer element may include a protrusion. The method may further include positioning the protrusion in the cavity. The method may further include extending a strap through the through hole and the second through hole. In some instances, an engagement of protrusion and the roller element within the cavity limits rotational movement of the display housing with respect to the base portion. Also, in some instances, the strap engages the convex surface when the display housing is positioned over the base portion. 
     Other systems, methods, features and advantages of the embodiments will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the embodiments, and be protected by the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  illustrates an isometric view of an embodiment of a system having a first housing part and a second housing part coupled to a hinge assembly, in accordance with some described embodiments; 
         FIG. 2  illustrates an isometric view of the system shown in  FIG. 1 , with the system transitioned to a closed position; 
         FIG. 3  illustrates a side view of the system shown in  FIGS. 1 and 2 , showing the first housing part in contact with the second housing part; 
         FIG. 4  illustrates an isometric view of the hinge assembly; 
         FIG. 5  illustrates a cross sectional view of the hinge assembly shown in  FIG. 4 , taken along line A-A, showing the strap extending through the roller elements and the spacer elements; 
         FIG. 6  illustrates a partial cross sectional view of the system in the open position, showing several additional structural features of the hinge assembly; 
         FIG. 7  illustrates a partial cross sectional view of the system shown in  FIG. 6 , showing the system transitioning from the open position to a partially closed position; 
         FIG. 8  illustrates an enlarged side view of the system shown in  FIG. 7 , showing the system transitioning from the partially closed position to the closed position; 
         FIG. 9  illustrates an enlarged cross sectional view of the system and the hinge assembly in the closed position, showing various interactions between the strap, the roller elements, and the spacer elements; 
         FIG. 10  illustrates a plan view of an alternate embodiment of a strap, in accordance with some described embodiments; 
         FIG. 11  illustrates a plan view of the strap shown in  FIG. 10 , showing the strap pulled in tension; 
         FIG. 12  illustrates an isometric view of an alternate embodiment of a strap connected to a tensioning element by a composite material; 
         FIG. 13  illustrates a plan view of the strap shown in  FIG. 12 , showing a fastener capable of coupled with the tensioning element; 
         FIG. 14  illustrates an isometric view of an alternate embodiment of a system, in accordance with some described embodiments; 
         FIG. 15  illustrates a side view of the system shown in  FIG. 14 ; 
         FIG. 16  illustrates an isometric view of a roller element and a spacer element of an alternate embodiment of a hinge assembly, in accordance with some described embodiments; 
         FIG. 17  illustrates a cross sectional view of a hinge assembly, showing multiple roller elements coupled with multiple spacer elements having protrusions positioned in the openings of the roller elements; 
         FIG. 18  illustrates an enlarged partial cross sectional view of an alternate embodiment of a system that includes the hinge assembly shown in  FIG. 17 , in accordance with some described embodiments; 
         FIG. 19  illustrates an enlarged partial cross sectional view of the system shown in  FIG. 18 , showing the hinge assembly transitioned from the partially closed position to a closed position; 
         FIG. 20  illustrates an enlarged cross sectional view of an alternate embodiment of a system having a hinge assembly that includes spacer elements designed to contact one another, in accordance with some described embodiments; 
         FIG. 21  illustrates an enlarged cross sectional view of the system shown in  FIG. 20 , further showing the system in a closed position and several adjacent spacer elements in contact with one another; 
         FIG. 22  illustrates an enlarged side view of an alternate embodiment of a system having a hinge assembly that includes spacer elements with magnetic elements, in accordance with some described embodiments; 
         FIG. 23  illustrates an enlarged side view of the system shown in  FIG. 22 , further showing the system in a closed position and several adjacent spacer elements magnetically coupled with one another by way of magnetic elements; 
         FIG. 24  illustrates an enlarged side view of the system shown in  FIGS. 22 and 23 , showing a first set of adjacent spacer elements magnetically coupled with one another to retain the system in a partially closed position; 
         FIG. 25  illustrates an enlarged side view of the system shown in  FIG. 24 , showing a second set of adjacent spacer elements magnetically coupled with one another to retain the system in a partially closed position; 
         FIG. 26  illustrates a side view of an alternate embodiment of a system having a hinge assembly with extended spacer elements, in accordance with some described embodiments; 
         FIG. 27  illustrates a side view of the system shown in  FIG. 26 , showing the system in the closed position; 
         FIG. 28  illustrates a side view of an embodiment of a strap formed from multiple materials designed to limit movement of the strap, in accordance with some described embodiments; 
         FIG. 29  illustrates an isometric view of an embodiment of a hinge assembly, showing straps positioned between segmented roller elements and spacer elements; 
         FIG. 30  illustrates an isometric view of an embodiment of a strap with an end piece coupled to the strap, in accordance with some described embodiments; 
         FIG. 31  illustrates a cross sectional view of the strap shown in  FIG. 30 , taken along line B-B, showing varies layers of a composite that forms the end piece and the strap; 
         FIG. 32  illustrates a plan view of a system, showing several straps anchored into the system, in accordance with some described embodiments; 
         FIG. 33  illustrates an isometric view of an alternate embodiment of a system having a hinge assembly coupled to a first housing part and a second housing part, with the system in an open position, in accordance with some described embodiments; 
         FIG. 34  illustrates an isometric view of the system shown in  FIG. 33 , with the system transitioned to a closed position; 
         FIG. 35  illustrates an isometric view of a segment of the hinge assembly; 
         FIG. 36  illustrates a cross sectional view of the system shown in  FIG. 35 , showing relative movement of the first housing part with respect to the second housing part; 
         FIG. 37  illustrates an isometric view of an alternate embodiment of a system having a hinge assembly coupled to a first housing part and a second housing part, with the system in an open position, in accordance with some described embodiments; 
         FIG. 38  illustrates an isometric view of the system shown in  FIG. 37 , with the system transitioned to a closed position; 
         FIG. 39  illustrates an isometric view of the system shown in  FIGS. 37 and 38 , with portions of the first housing part and the second housing part removed to show additional features of the hinge assembly; 
         FIG. 40  illustrates a cross sectional view of the system shown in  FIGS. 37-39 , with the system in the closed position; 
         FIG. 41  illustrates a cross sectional view of an alternate embodiment of a system in a closed position, showing the system having a hinge assembly with a strap extending along an outer region of the hinge assembly; 
         FIG. 42  illustrates a cross sectional view of an alternate embodiment of a system in a closed position, showing the system having a hinge assembly with a strap extending along an inner region of the hinge assembly; 
         FIG. 43  illustrates an exploded view of an embodiment of a hinge assembly, in accordance with some described embodiments; 
         FIG. 44  illustrates an isometric view of an alternate embodiment of a hinge assembly, showing the hinge assembly having segmented spacer elements, in accordance with some described embodiments; 
         FIG. 45  illustrates a cross sectional view of the hinge assembly shown in  FIG. 44 , showing the middle spacer segments having protruding features that extending into cavities of the roller elements, in accordance with some described embodiments; 
         FIG. 46  illustrates a side view of a roller element and a spacer element, showing a comparison between a radius of the roller element and a radius of curvature of the spacer element, in accordance with some described embodiments; 
         FIG. 47  illustrates a side view of an embodiment of a hinge assembly that includes several roller elements and the spacer element, showing a relationship between roller elements and spacer elements, in accordance with some described embodiments; 
         FIG. 48  illustrates a partial cross sectional view of an embodiment of a roller element, showing features of a through hole in the roller element, in accordance with some described embodiments; 
         FIG. 49  illustrates a cross sectional view of an embodiment of a system that includes a hinge assembly with a strap limiting movement of the roller elements and the spacer elements, in accordance with some described embodiments. 
         FIG. 50  illustrates a side view of an embodiment of a hinge assembly that includes a spacer element and roller elements, with the spacer element having a pin designed to limit movement of the roller elements, in accordance with some described embodiments; 
         FIG. 51  illustrates a side view of an embodiment of a hinge assembly that includes a spacer element and roller elements, with the spacer element having protruding features designed to limit movement of the roller elements, in accordance with some described embodiments; 
         FIG. 52  illustrates a side view of an embodiment of a hinge assembly that includes a spacer element and roller elements, with the spacer element having an enhanced protruding features designed to limit movement of the roller elements, in accordance with some described embodiments; 
         FIG. 53  illustrates a side view of an embodiment of a system in an open position, showing a dovetail configuration of a spacer element limiting movement of roller elements in the open position, in accordance with some described embodiments; 
         FIG. 54  illustrates a side view of the system shown in  FIG. 53 , showing the system transition from the open position to a closed position; 
         FIG. 55  illustrates a side view of an embodiment of a hinge assembly, showing a spacer element having a protruding feature that is off-center on a concave surface of the spacer element, in accordance with some described embodiments; 
         FIG. 56  illustrates a side view of an embodiment of a hinge assembly, showing the spacer element having multiple protruding features that are off-center on concave surfaces of the spacer element, in accordance with some described embodiments; 
         FIG. 57  illustrates an isometric view of a modular spacer element used with a hinge assembly, in accordance with some described embodiments; 
         FIG. 58  illustrates an isometric view of an embodiment of a system that includes a hinge assembly with modular spacer elements, in accordance with some described embodiments; 
         FIG. 59  illustrates a cross sectional view of an embodiment of a system that includes a hinge assembly and a strap, showing the system transition from an open position to an open position, in accordance with some described embodiments; 
         FIG. 60  illustrates a graph of effective length of a strap versus angle; 
         FIG. 61  illustrates a cross sectional view of an embodiment of a system in a closed position, showing the system with a strap that is offset from respective centers of rolling elements and spacer elements that form a hinge assembly, in accordance with some described embodiments; 
         FIG. 62  illustrates a cross sectional view of the system shown in  FIG. 61 , showing the system in an open position and the strap engaging the stop mechanism; 
         FIG. 63  illustrates an isometric view of an alternate embodiment of a system having recesses designed to accommodate a hinge assembly, in accordance with some described embodiments; 
         FIG. 64  illustrates a partial cross sectional view of the system shown in  FIG. 63 , showing the system in an open position; 
         FIG. 65  illustrates a partial cross sectional view of the system shown in  FIG. 63 , showing the system in a closed position; 
         FIG. 66  illustrates a plan view of an alternate embodiment of a strap that includes several blocks, in accordance with some described embodiments; 
         FIG. 67  illustrates a cross sectional view of the strap shown in  FIG. 66 , showing the strap in a bent configuration; 
         FIG. 68  illustrates a cross sectional view of the strap shown in  FIG. 66 , showing the strap in a flat configuration; 
         FIG. 69  illustrates a cross sectional view of an embodiment of a roller element, showing the roller undergoing a cutting operation by a tool, in accordance with some described embodiments; 
         FIG. 70  illustrates a cross sectional view of the roller shown in  FIG. 69 , showing the roller element further undergoing the cutting operation; 
         FIG. 71  illustrates a cross sectional view of the roller element shown in  FIG. 70 , showing the roller element subsequent to the cutting operation; 
         FIG. 72  illustrates an isometric view of an embodiment of a roller element, showing an insert designed for integration with the roller element, in accordance with some described embodiments; 
         FIG. 73  illustrates a cross sectional view of the roller element shown in  FIG. 72 , showing the insert positioned in the roller element; 
         FIG. 74  illustrates a cross sectional view of an embodiment of a roller element, showing the roller element having an insert that defines an opening for a strap, in accordance with some described embodiments; 
         FIG. 75  illustrates a cross sectional view of an embodiment of a roller element, showing the roller element that includes a molded insert that defines a single surface for a strap, in accordance with some described embodiments; 
         FIG. 76  illustrates an isometric view of an embodiment of a roller element, showing the roller element formed by coupling two structures together along their respective longitudinal axes, in accordance with some described embodiments; 
         FIG. 77  illustrates an isometric view of an embodiment of a roller element, showing the roller element formed by coupling a structure into an opening of another structure, in accordance with some described embodiments; 
         FIG. 78  illustrates an exploded view of an embodiment of a roller element, showing the roller element prior to an assembly operation, in accordance with some described embodiments; 
         FIG. 79  illustrates an isometric view of the roller element shown in  FIG. 78 , showing the roller element subsequent to an assembly operation; 
         FIG. 80  illustrates an isometric view of an embodiment of a spacer element, showing the spacer element formed by coupling two structures together along their respective longitudinal axes, in accordance with some described embodiments; 
         FIG. 81  illustrates an isometric view of an embodiment of a spacer element, showing the spacer element formed by coupling two structures together along different axes, in accordance with some described embodiments; 
         FIG. 82  illustrates an isometric view of an embodiment of a spacer element, showing an insert designed for integration with the spacer element, in accordance with some described embodiments; 
         FIG. 83  illustrates an isometric view of an alternate embodiment of a system, showing a cover that extends over a hinge assembly, in accordance with some described embodiments; 
         FIG. 84  illustrates an isometric view of an alternate embodiment of a system, showing a cover and several rails of a hinge assembly designed to maintain the cover, in accordance with some described embodiments; 
         FIG. 85  illustrates a side view of the system shown in  FIG. 84 , showing the cover  3781  passing through the rails; 
         FIG. 86  illustrates an isometric view of an alternate embodiment of a system of a system, showing several plates that cover the hinge assembly, in accordance with some described embodiments; 
         FIG. 87  illustrates a side view of the system shown in  FIG. 86 , showing the plates covering the hinge assembly; 
         FIG. 88  illustrates a side view of a hinge assembly, showing a cover that wraps around a roller element and passes through consecutive spacer elements, in accordance with some described embodiments; 
         FIG. 89  illustrates an alternate embodiment of a having a hinge assembly coupled to a housing part and a stand, in accordance with some described embodiments; 
         FIG. 90  illustrates an alternate embodiment of a system having a hinge assembly coupled to a first housing part and a second housing part, with the hinge assembly having a single roller element, in accordance with some described embodiments; 
         FIG. 91  illustrates an alternate embodiment of a system having a hinge assembly coupled to a housing part and a stand, in accordance with some described embodiments; 
         FIG. 92  illustrates an isometric view of an embodiment of a system having multiple hinge assemblies, in accordance with some described embodiments; 
         FIG. 93  illustrates a side view of the system shown in  FIG. 92 , showing the system in a closed position; 
         FIG. 94  illustrates a side view of the system shown in  FIGS. 92 and 93 , showing the system in an open position; 
         FIG. 95  illustrates a side view of the system shown in  FIG. 94 , further showing the second housing part positioned at a predetermined angle with respect to the third housing part; 
         FIG. 96  illustrates an isometric view of an embodiment of an electronic device, in accordance with some described embodiments; 
         FIG. 97  illustrates an isometric view of an embodiment of an electronic device, in accordance with some described embodiments; 
         FIG. 98  illustrates a side view of the electronic device shown in  FIG. 97 , showing the electronic device in a closed position; 
         FIG. 99  illustrates a side view of an alternative embodiment of an electronic device, showing the electronic device in a closed position; 
         FIG. 100  illustrates an isometric view of an alternate embodiment of an electronic device, showing components of the hinge assembly having chamfered regions, in accordance with some described embodiments; 
         FIG. 101  illustrates a side view of the electronic device shown in  FIG. 100 , showing the electronic device in a closed position; 
         FIG. 102  illustrates an isometric view of an alternate embodiment of an electronic device, showing a hinge assembly that includes a roller element integrated with a display housing and a spacer element integrated with a base portion, in accordance with some described embodiments; 
         FIG. 103  illustrates an exploded view of the hinge assembly of the electronic device shown in  FIG. 102 ; 
         FIG. 104  illustrates a side view of the electronic device shown in  FIG. 102 ; 
         FIG. 105  illustrates a block diagram of an electronic device, in accordance with some described embodiments; and 
         FIG. 106  illustrates a flowchart showing a method for assembling a hinge assembly of a portable computing device, in accordance with some described embodiments. 
     
    
    
     Those skilled in the art will appreciate and understand that, according to common practice, various features of the drawings discussed below are not necessarily drawn to scale, and that dimensions of various features and elements of the drawings may be expanded or reduced to more clearly illustrate the embodiments of the present invention described herein. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one 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 described embodiments as defined by the appended claims. 
     In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. 
     The following disclosure relates to hinge assemblies designed to couple together one or more parts of a system. A system described herein may include electronic devices (such as laptop computing devices and desktop computing devices) or accessory devices (such as folios and covers). The hinge assembly may include multiple roller elements having a generally cylindrical shape. The hinge assembly may further include multiple spacer elements, with a spacer element positioned between adjacent roller elements. During movement of one part relative to another part, the roller elements rotate or roll along a surface of the spacer elements. Further, in addition to the rotation of the roller elements, the roller elements and the spacer elements can act in concert and provide synchronized movement. In other words, when one of the parts is moved, the roller elements and the spacer elements move together at the same time, while the roller elements rotate along surfaces of the spacer elements. 
     A hinge assembly that uses a combination of roller elements and spacer elements offers several advantages over traditional hinge assemblies. For example, traditional hinge assemblies that use a torsion bar impart rotational stresses on the torsion bar, as one end of the torsional bar rotates with respect to another end of the torsion bar (causing a twisting of the torsion bar). However, hinge assemblies described herein allow the entire cylindrical body of the roller elements to rotate along the spacer elements without twisting. As a result, rotational stresses are not imparted on the roller elements. Moreover, the rotational movement of the roller elements is inversely proportional to the number of roller element. In this regard, a hinge assembly with a relatively high number of roller elements includes a relatively small amount of rotational movement per roller elements. As a result, less movement of the roller elements may lead to less wear on the roller elements and/or the spacer elements over time. 
     Contrary to traditional hinge assemblies in which a substantially majority of the structural elements is stored in one (or both) of the parts, the hinge assemblies described herein are positioned substantially outside, or external to, the parts. For example, both the roller elements and the spacer elements are externally positioned with respect to the parts. In this regard, additional internal volume or space within the parts is available for other components. 
     In order to maintain engagement between the roller elements and the spacer elements, the hinge assembly may include a strap (or straps) passing through each of the roller elements and the spacer elements. The strap may influence the frictional engagement between roller elements and the spacer elements. The frictional force, F f , between a roller element engaged with a spacer element can be derived by:
 
 F   f   =μN  
 
where μ is the coefficient of friction of the surface of the roller element and the surface of the spacer element, and N is the normal or perpendicular force that pushes the elements together. The normal force, N, may be a function of the weight of the roller element, when positioned over the spacer elements, as well the force the strap applies to maintain the engagement between the roller element and the spacer element. The frictional engagement can affect not only the ability for the roller elements to roll along the spacer elements, but also the ability of the hinge assembly to remain in a fixed position, and in turn, maintain the parts (coupled to the hinge assembly) in a fixed position. In this regard, the hinge assembly may include a tensioning element coupled to one end of the strap. The tensioning element may provide a pulling force on the strap, which in turn, influences the degree by which the roller elements engage the spacer elements. The tensioning element may include a constant tensioning element or an adjustable tensioning element, with the latter having the ability altered the normal force N desired.
 
     Further, the strap may act as a stiffening element, or stiffener, for the hinge assembly, allowing the hinge assembly to maintain a fixed position of the parts of the system. For example, when one of the parts is moved relative to another part from one position to another position, the stiffness of the strap allows the hinge assembly to maintain the part in the other position. Further, when one part moves relative to the another part, the strap may be used to counterbalance, or offset, the force (provided by the weight) of the moved part, and the moved part can remain fixed position in a desired position after the part ceases movement. 
     In some instances, hinge assemblies described herein may include multiple straps. The multiple straps can be used to increase the overall stiffness of the hinge assembly. Alternatively, each strap may provide a specific function. For example, one strap may keep the roller elements in a desired frictional engagement, while another strap provides stiffness. Further, additional strap may include a flexible circuit designed to route electrical signals between operational components of the system. Accordingly, in some instances, one housing part connected to the hinge assembly may include a display assembly, while another housing part connected to the hinge assembly may include a processor circuit. The strap used as a flexible circuit may electrically connect to the display assembly to the processor circuit to place the display assembly and the processor circuit in electrical communication with each other. 
     These and other embodiments are discussed below with reference to  FIGS. 1-106 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  illustrates an isometric view of an embodiment of a system  100  having a first housing part  102   a  and a second housing part  102   b  coupled to a hinge assembly  104 , in accordance with some described embodiments. The hinge assembly  104  is designed to allow relative movement of the first housing part  102   a  with respect to the second housing part  102   b , and vice versa. The hinge assembly  104  may include several roller elements (not labeled) along with several spacer elements (not labeled), with a spacer element positioned between adjacent roller elements. As shown, the system  100  is an open position, with the first housing part  102   a  rotated away from the second housing part  102   b , but can transition to other positions. These features will be shown and described below. 
     Although not shown, in some embodiments, at least one of the first housing part  102   a  and the second housing part  102   b  carries a display assembly designed to present visual information in the form of text and images (video or still images). Further, although not shown, in some embodiments, at least one of the first housing part  102   a  and the second housing part  102   b  carries an input mechanism (or multiple input mechanisms) including keyboard assembly and a touch pad, each of which is capable of providing a command or input to a processor circuit (not shown) within at least one of the first housing part  102   a  and the second housing part  102   b , with the input or command being used to control the display assembly. Also, the system  100  is designed such that the hinge assembly  104  lies outside, or at least substantially outside, the first housing part  102   a  and the second housing part  102   b . In this manner, when the first housing part  102   a  and/or the second housing part  102   b  carry the above-referenced components, the first housing part  102   a  and the second housing part  102   b  can include additional space or internal volume that would otherwise be occupied by the hinge assembly  104 . 
       FIG. 2  illustrates an isometric view of the system  100  shown in  FIG. 1 , with the system  100  transitioned to a closed position. The hinge assembly  104  allows the first housing part  102   a  to rotate or pivot over the second housing part  102   b . As shown, in the closed position, the first housing part  102   a  covers, or at least substantially, covers the second housing part  102   b . Referring again to  FIG. 1 , the “open position” may refer to the first housing part  102   a  being folded away from the second housing part  102   b  such that first housing part  102   a  is positioned 180 degrees, or at least approximately 180 degrees, away from the second housing part  102   b . Also, phrases such as “partially open position” and “partially closed position” may be used throughout this detailed description to refer to a position or positions in which the first housing part  102   a  and the second housing part  102   b  are in a position (relative to each other) between the open position and the closed position. Accordingly, the hinge assembly  104  provides the system  100  with flexibility and allows for several different positions. 
       FIG. 3  illustrates a side view of the system  100  shown in  FIGS. 1 and 2 , showing the first housing part  102   a  in contact with the second housing part  102   b . As shown, the hinge assembly  104  allows at least partial contact between the first housing part  102   a  and the second housing part  102   b . For example, the hinge assembly  104  may allow movement of the first housing part  102   a  relative to the second housing part  102   b  such that a first edge  106   a  of the first housing part  102   a  can contact a first edge  108   a  of the second housing part  102   b . Although not shown, the hinge assembly  104  may allow movement of the first housing part  102   a  relative to the second housing part  102   b  such that a second edge  106   b  of the first housing part  102   a  can contact a second edge  108   b  of the second housing part  102   b , even without contact between the first edge  106   a  and the first edge  108   a . Further, the hinge assembly  104  may allow movement of the first housing part  102   a  relative to the second housing part  102   b  such that a first surface  110   a  of the first housing part  102   a  can lie on or over a first surface  112   a  of the second housing part  102   b . Further, the hinge assembly  104  may allow the first housing part  102   a  to rotate relative to the second housing part  102   b  such that a second surface  110   b  of the first housing part  102   a  can lie on or over a second surface  112   b  of the second housing part  102   b.    
       FIG. 4  illustrates an isometric view of the hinge assembly  104 . The hinge assembly  104  may include several roller elements, such as a first roller element  114   a , a second roller element  114   b , a third roller element  114   c , a fourth roller element  114   d , and a fifth roller element  114   e . The hinge assembly  104  may further include several spacer elements, such as a first spacer element  116   a , a second spacer element  116   b , a third spacer element  116   c , and a fourth spacer element  116   d . As shown, a spacer element can be positioned between adjacent roller elements. For example, the first spacer element  116   a  is positioned between the first roller element  114   a  and the second roller element  114   b . Also, the first spacer element  116   a  includes a concave design to receive, or at least partially receive, the first roller element  114   a  and the second roller element  114   b . The concave design of the first spacer element  116   a  further allows the first roller element  114   a  and the second roller element  114   b  to slide, or rotationally move, along the first spacer element  116   a . While a discrete number of roller elements and spacer elements are shown, the number of roller elements and spacer elements may vary for the hinge assembly  104 . Generally, for n roller elements in a hinge assembly  104 , there will be n−1 spacer elements. However, in some instances, for n spacer elements in a hinge assembly  104 , there will be n−1 roller elements. 
     The hinge assembly  104  may further include a first housing attachment  118   a  and a second housing attachment  118   b  designed to secure with the first housing part  102   a  and the second housing part  102   b  (shown in  FIGS. 1 and 2 ), respectively. However, in some instances, the first housing part  102   a  includes a concave portion and the second housing part  102   b  includes a concave portion to receive the first roller element  114   a  and the fifth roller element  114   e , respectively, and the first housing attachment  118   a  and the second housing attachment  118   b  are not required. 
     Also, the hinge assembly  104  may further include a strap  120  that passes or extends through the aforementioned roller elements, spacer elements, and housing attachment elements. The strap  120  is designed to maintain an engagement between the roller elements, the spacer elements, and the housing attachment elements. Further, in some instances, the strap  120  can maintain the hinge assembly  104 , and in turn the system  100  (shown in  FIGS. 1 and 2 ), in a desired position or configuration. In this regard, the strap  120  may provide the hinge assembly  104  with stiffness such that when, for example, a force is provided to the first housing part  102   a  (shown in  FIGS. 1 and 2 ) that moves or rotates the first housing part  102   a  relative to the second housing part  102   b  (shown in  FIGS. 1 and 2 ), the first housing part  102   a  maintains its position when the force to the first housing part  102   a  is no longer provided. Accordingly, the strap  120  may be referred to as a stiffening element. Also, the stiffness of the strap  120  (as well as the additional stiffness provided by any additional straps, when applicable) may provide the hinge assembly  104  with synchronous motion. This will be shown and discussed below. 
     The strap  120  may include a material (or materials) such as a metal (including steel), glass fiber, and/or carbon fiber. Also, the material and the thickness of the strap  120  are selected to allow the hinge assembly  104  to include a desired bend radius as well as a desired stiffness. The thickness of the strap  120  may be proportional to the stiffness, and inversely proportional to the bend radius. Accordingly, the thickness should be selected to achieve desired properties of the hinge assembly  104 . One end of the strap  120  may be positioned within the first housing part  102   a  (shown in  FIGS. 1 and 2 ), while the other (opposite) end may be positioned within the second housing part  102   b  (shown in  FIGS. 1 and 2 ), with fasteners (as a non-limiting example) used to secure each end of the strap  120  with a respective housing part. Also, at least one end of the strap  120  may be secured to a tensioning element (not shown in  FIG. 4 ) designed to provide a pulling force, and thereby providing tension, to the strap  120 . This will be shown and described below. 
       FIG. 5  illustrates a cross sectional view of the hinge assembly  104  shown in  FIG. 4 , taken along line A-A, showing the strap  120  extending through the roller elements and the spacer elements. As shown, each of the roller elements, the spacer elements, and the housing attachment elements includes an opening, or through hole, that is generally aligned with an adjacent and engaging element. This allows for the strap  120  to pass through the elements. For example, the first roller element  114   a  is adjacent to and engaged with the first spacer element  116   a  and the first housing attachment  118   a . The first roller element  114   a  includes an opening  122  that is aligned, or at least partially aligned, with an opening  124  of the first housing attachment  118   a  and an opening  126  of the first spacer element  116   a . As a result, the strap  120  can readily pass through these elements via their respective openings, as well as the remaining elements, which include openings with a similar relationship. Also, as shown in  FIG. 5 , the roller elements may include an asymmetric opening. For example, the opening  122  of the first roller element  114   a  includes a flat surface  128   a  and a convex surface  128   b . In this regard, when the hinge assembly  104  transitions to a closed position (see  FIG. 2 ), the strap  120  bends and rests along the convex surface  128   b  of the first roller element  114   a . Accordingly, the convex surface  128   b  can further accommodate the strap  120  in certain positions. Although not shown, the spacer elements and the housing attachment elements may include an opening with a surface similar to that of the convex surface  128   b  of the first roller element  114   a.    
     While the hinge assembly  104  shown in  FIGS. 3-5  includes a single strap, the hinge assembly  104  may include multiple straps in addition to the strap  120 . Further, each strap may include different materials, and accordingly, different functions. For example, when the hinge assembly  104  includes three straps, a first strap can be used to maintain an engagement between the roller elements, the spacer elements, and the housing attachment elements. A second strap can be used to provide stiffness to the hinge assembly  104  and maintain the hinge assembly  104  (and the system  100 , in  FIGS. 1 and 2 ) in a desired position. A third strap can be used as a flexible circuit that provides electrical communication between operational components in the first housing part  102   a  (shown in  FIGS. 1 and 2 ), such as a display assembly and/or a processor circuit, and operational components in the second housing part  102   b  (shown in  FIGS. 1 and 2 ), such as a keyboard assembly, a touch pad, and a display function bar. Alternatively, in some embodiments, the strap  120  defines a single strap in the hinge assembly  104  that provides all three functions. Accordingly, in some embodiments, the strap  120  maintains engagement between the various elements of the hinge assembly  104 , provides a stiffening feature, and also provides an electrical communication pathway between operational components in the housing parts. 
       FIG. 6  illustrates a partial cross sectional view of the system  100  in the open position, showing several additional structural features of the hinge assembly  104 . As shown, the first housing attachment  118   a  and the second housing attachment  118   b  are positioned in, and secured to, the first housing part  102   a  and the second housing part  102   b , respectively. Also, one end of the strap  120  is positioned in the first housing part  102   a  while another opposing end of the strap  120  is positioned in the second housing part  102   b . The system  100  may include a first fastener  132   a  that secures one end of the strap  120  to the first housing part  102   a , and may further include a second fastener  132   b  that secures the other opposing end of the strap  120  to a strap retention element  134 . The strap retention element  134  is coupled to a tensioning element  136 . As a result, the strap  120  may receive a pulling force from the tensioning element  136 . 
     The pulling force provided by the tensioning element  136  is designed to provide tension to the strap  120 . In this regard, when an end of the strap  120  is anchored to the first housing part  102   a  (as shown in  FIG. 6 ), the strap  120 , when pulled by the tensioning element  136 , can provide an increased normal/perpendicular force to the roller elements and the spacer elements. As a result, the force provided by the strap  120 , by way of the tensioning element  136 , can increase the frictional forces between the roller elements and the spacer elements. This may enhance the experience of moving the first housing part  102   a  relative to the second housing part  102   b , or vice versa. This may further enhance the ability of the strap  120  to maintain the first housing part  102   a  in one or more fixed positions relative to the second housing part  102   b . In the embodiment shown in  FIG. 6 , the tensioning element  136  is a spring that provides a constant tension to the strap  120 . However, in some embodiments (shown later), a tensioning element can provide an adjustable tension or adjustable pulling force to a strap. 
     The stiffness of the strap  120  may assist in providing synchronous motion of the roller elements and the spacer elements. For example, while the system  100  transitions from the open position (shown  FIG. 1 ) to the closed position (shown  FIG. 2 ), or vice versa, the roller elements and the spacer elements move in unison (with each of the roller elements rotating relative to the spacer elements). In other words, while the system  100  transitions from the open position to the closed position, or vice versa, both the roller elements and the spacer elements can move at the same time (although the amount of movement of each element may vary), while following the changing curvature of the strap  120  from a generally straight configuration (in the open position) to a substantially curved configuration (in the closed position). In this regard, the stiffness of the strap  120  can influence the motion of the roller elements and the spacer elements, and material makeup of the strap  120  should be selected to provide a desired stiffness and a desired movement (such as a desired synchronous motion) of the roller elements and spacer elements. It should be noted that the coordinated movement of the roller elements and the spacer elements refers to two-dimensional movement, and accordingly, the roller elements may simultaneously roll and move in two-dimension. This will be shown and discussed below. 
       FIG. 7  illustrates a partial cross sectional view of the system  100  shown in  FIG. 6 , showing the system  100  transitioning from the open position to a partially closed position. A “partially closed position,” which refers to a position other than the open or closed position, and can be used interchangeably with “a partially open position.” As shown, the hinge assembly  104  allows the first housing part  102   a  to move or rotate relative to the second housing part  102   b . During the movement of the first housing part  102   a , each of the roller elements can rotationally move (or roll or slide) relative to the spacer elements, as indicated by the arrows. For example, during movement of the first housing part  102   a  (relative to the second housing part  102   b ), the first roller element  114   a  can rotationally move along a concave surface of the first spacer element  116   a  and along a concave surface of the first housing attachment  118   a . Also, the second roller element  114   b  can also rotate (at the same time as the first roller element  114   a ), during movement of the first housing part  102   a , along a concave surface of the first spacer element  116   a  and along a concave surface of the second spacer element  116   b . The remaining roller elements may also rotate in a similar manner with respect to their respective spacer elements. Further, during movement of the first housing part  102   a  relative to the second housing part  102   b , the spacer elements and the roller elements may move in two dimensions, while the roller elements are rotating/rolling along the concave surfaces of the spacer elements. This is due in part to the strap  120  and the pulling force provided to the strap  120  from the tensioning element  136 . 
       FIG. 8  illustrates an enlarged side view of the system  100  shown in  FIG. 7 , showing the system  100  transitioning from the partially closed position to the closed position. As shown, during movement of the first housing part  102   a  relative to the second housing part  102   b , the structural elements of the hinge assembly  104  can synchronously move together. For example, similar to the partially closed position (shown in  FIG. 7 ), during movement of the first housing part  102   a  relative to the second housing part  102   b , the first roller element  114   a  continues to rotate or roll along a concave surface of the first spacer element  116   a  and along a concave surface of the first housing attachment  118   a . At the same time, the second roller element  114   b  can continue to rotate along a concave surface of the first spacer element  116   a  and along a concave surface of the second spacer element  116   b . The remaining roller elements may also rotate in a similar manner with respect to their respective spacer elements. Further, during movement of the first housing part  102   a  relative to the second housing part  102   b , the spacer elements and the roller elements may continue move in two dimensions, while the roller elements continue rotating/rolling along the concave surfaces of the spacer elements, until the system  100  reaches the closed position. 
     While  FIGS. 6-8  illustrate an example of the system  100  transitioning from the open position to the closed position, it should be understood that the roller elements and the spacer elements move in a synchronous manner when the system  100  transitions from the closed position to the open position. However, the roller elements may rotate in rotational direction that is opposite to what is shown in  FIGS. 6-8 . In other words, if the roller elements rotate in a clockwise manner from the open position to the closed position, the roller elements will rotate in a counter-clockwise manner from the open position to the closed position. Also, when transitioning from the closed position to the open position, the synchronous movement of the roller elements and the spacer elements will mirror the movement from the open position to the closed position. 
       FIG. 9  illustrates an enlarged cross sectional view of the system  100  and the hinge assembly  104  in the closed position, showing various interactions between the strap  120 , the roller elements, and the spacer elements. As shown in  FIG. 9 , when the system  100  is in the closed position, some elements of the hinge assembly  104  may engage the strap  120 , thereby providing a mechanical stop. For example, the strap  120  can become pinched or clamped between the first roller element  114   a  and the first spacer element  116   a . As shown in the enlarged view, in the closed position, the strap  120  may engage a portion (including an edge) of the convex surface  128   b  of the first roller element  114   a  and a portion of a surface  138  (including an edge of a top surface) of the first spacer element  116   a . In the closed position, in order to further provide the mechanical stop, the strap  120  may engage additional roller elements and spacer elements in a similar manner. For example, the strap  120  may be pinched or clamped between the second roller element  114   b  and the second spacer element  116   b  in a manner similar to that of the first roller element  114   a  and the first spacer element  116   a  described above. In the closed position, the strap  120  may be pinched or clamped between each respective pair of a roller element and a spacer element, as shown in  FIG. 9 , and further provide mechanical stop of the hinge assembly  104 . 
       FIG. 10  illustrates a plan view of an alternate embodiment of a strap  220 , in accordance with some described embodiments. The strap  220  may be integrated into one or more hinge assemblies (not shown in  FIG. 10 ) described herein. The first end  221   a  and the second end  221   b  may include a first extension  223   a  and a second extension  223   b , respectively. The strap  220  can be affixed with housing parts of a system (not shown in  FIG. 10 ) by the first extension  223   a  and the second extension  223   b . In this manner, the strap  220  does not need fastening holes. 
     Also, the central portion  221   c  may be formed from glass fiber in order to enhance resistance against stress and strain. As shown, the strap  220  may include one or more materials. For example, the strap  220  may include a first end  221   a  and a second end  221   b  connected with the first end  221   a  by a central portion  221   c . For example, the first end  221   a  and the second end  221   b  may include a flexible or stretchable material, such as elastic (as a non-limiting example). The first end  221   a  and the second end  221   b  may include several cuts, or slits, that form small openings. For example, the strap  220  may include a first cut  225   a  and a second cut  225   b , representative of several additional cuts. 
       FIG. 11  illustrates a plan view of the strap  220  shown in  FIG. 10 , showing the strap  220  pulled in tension, as denoted by forces represented by arrows pointed in opposite directions. As shown, when the strap  220  is pulled in tension, the strap  220  can elongate along the first end  221   a  and the second end  221   b . This is due in part to the stretchable characteristics of the first end  221   a  and the second end  221   b , along with the first end  221   a  and the second end  221   b  separating along the cuts to form openings. For example, the first end  221   a  includes an opening  227  (representative of several additional openings) defined by the first cut  225   a . The stretching ability and the cuts to the first end  221   a  and the second end  221   b  provide the strap  220  with flexibility such that the strap  220  includes spring like characteristics. As a result, in some instances, a system that incorporates the strap  220  may not require a tensioning element  136  (shown in  FIG. 6 ). 
       FIG. 12  illustrates an isometric view of an alternate embodiment of a strap  320  connected to a tensioning element  370  by a composite material  331 . The tensioning element  370  is designed to act as a spring and flex in response to a force, and may provide tension to the strap  320 . The composite material  331  is designed to bond the strap  320  with the tensioning element  370 . Further, the composite material  331  can be applied to the strap  320  and the tensioning element  370  when the strap  320  is in a bent configuration, as shown in  FIG. 12 . In this manner, the composite material  331  can cure without inducing stresses on the strap  320 . 
       FIG. 13  illustrates a plan view of the strap  320  shown in  FIG. 12 , showing a fastener  332  capable of coupled with the tensioning element  370 . The fastener  332  may pass through an opening  333  of the tensioning element  370  and secure to the tensioning element  370 . The fastener  332  can be used to couple the strap  320  with housing part of a system (not shown in  FIG. 13 ). 
       FIG. 14  illustrates an isometric view of an embodiment of a system  300 , in accordance with some described embodiments. The system  300  may include a first housing part  302   a  and a second housing part  302   b . In some embodiments, the system  300  includes a laptop computer. In this regard, the first housing part  302   a  may include a display housing that carries a display (not shown in  FIG. 10 ) designed to present visual information in the form of still and motion images. Also, the second housing part  302   b  may include a keyboard and a touch input pad (not shown in  FIG. 10 ) designed to provide inputs to a central processing unit (not shown in  FIG. 10 ). 
     The system  300  may further include a hinge assembly  304  connected to the first housing part  302   a  and the second housing part  302   b . The hinge assembly  304  is designed to allow relative movement of the first housing part  302   a  with respect to the second housing part  302   b , and vice versa. The hinge assembly  304  may include several roller elements along with several spacer elements, with a spacer element positioned between consecutive roller elements. This will be shown and described below. 
     As shown in  FIG. 14  the hinge assembly  304  positions the system  300  in an open position. When the system  300  is a laptop computer, the open position is associated with a configuration in which the display, keyboard, and touch input pad are available for use. The open position may be associated with the first housing part  302   a  positioned at an angle  306   a  with respect to the second housing part  302   b . The angle  306   a  may be approximately in the range of 90 to 135 degrees. In some embodiments, the angle  306   a  is 135 degrees. Further, in some embodiments, the angle  306   a  represents the maximum angular displacement, or maximum rotational movement, of the first housing part  302   a  with respect to the second housing part  302   b . In this regard, the hinge assembly  304  may limit the angle  306   a  of the system. This will be further shown and described below. In some instances, as depicted by the dotted lines, the hinge assembly  304  may allow the first housing part  302   a  to travel to an angle  306   b  of approximately 180 degrees with respect to the second housing part  302   b , in which the first housing part  302   a  is co-planar with respect to the second housing part  302   b.    
       FIG. 15  illustrates a side view of the system  300  shown in  FIG. 14 . As shown in  FIG. 15 , the system  300  is in a closed position, in which the hinge assembly  304  allows the first housing part  302   a  to rotate with respect to the second housing part  302   b , and position the first housing part  302   a  over the second housing part  302   b  such that the first housing part  302   a  is parallel, or at least approximately parallel, with respect to the second housing part  302   b . As a result, the angular position of the first housing part  302   a  with respect to the second housing part  302   b  is zero. The closed position is generally associated with portability of the system  300  when the system  300  is not in use. 
       FIG. 16  illustrates an isometric view of a roller element  414  and a spacer element  416  of an alternate embodiment of a hinge assembly  404 , in accordance with some described embodiments. As shown, the spacer element  416  may include a first protrusion  442   a  on a first concave surface  444   a . The roller element  414  may include an opening  446 . When the roller element  414  is paired with the spacer element  416 , the first protrusion  442   a  can be positioned in the opening  446 . Accordingly, the opening  446  may include a diameter greater than that of the first protrusion  442   a . Further, the diameter of the opening  446  may be sufficiently larger than the diameter of the first protrusion  442   a  such that the roller element  414  can adequately rotate or roll along the first concave surface  444   a  when the hinge assembly  404  transitions a system (not shown in  FIG. 16 ) from an open position to a closed position, or vice versa. Also, the roller element  414  may include an opening  422  and the spacer element  416  may include an opening  424  that aligns with the opening  422  so that the hinge assembly  404  can receive a strap (not shown in  FIG. 16 ). The spacer element  416  may further include a second protrusion  442   b  on a second concave surface  444   b , with the second protrusion  442   b  and the second concave surface  444   b  being substantially similar to the first protrusion  442   a  and the first concave surface  444   a , respectively. Accordingly, the spacer element  416  can accommodate a second roller element (not shown in  FIG. 16 ) that is substantially similar to the roller element  414 . 
       FIG. 17  illustrates a cross sectional view of a hinge assembly  504 , showing multiple roller elements coupled with multiple spacer elements having protrusions positioned in the openings of the roller elements. As shown, the hinge assembly  504  includes a first spacer element  516   a  with multiple the concave surfaces designed to receive and engage a first roller element  514   a  and a second roller element  514   b . Further, the first spacer element  516   a  includes a first protrusion  542   a  positioned in an opening  546   a  of the first roller element  514   a . The first spacer element  516   a  includes a second protrusion  542   b  positioned in an opening  546   b  of the second roller element  514   b . Although not labeled, the remaining roller elements and spacer elements may include similar properties and relationships. 
       FIG. 18  illustrates an enlarged partial cross sectional view of an alternate embodiment of a system  500  that includes the hinge assembly  504  shown in  FIG. 17 , in accordance with some described embodiments. The system  500  may include a first housing part  502   a  and a second housing part  502   b , both of which are coupled to the hinge assembly  504  in a manner previously described. Also, although not shown, the hinge assembly  504  may include a strap that extends through the roller elements and spacer elements, and includes ends positioned in the first housing part  502   a  and the second housing part  502   b . The hinge assembly  504  may also include a tensioning element coupled to an end of the strap, similar to a manner previously described. 
     As shown, when the first housing part  502   a  is sufficiently moved or rotated relative to the second housing part  502   b , movement of some of the roller elements and spacer elements causes the protrusions (of the spacer elements) to engage a surface, or internal surface, of openings of the roller elements. For example, as shown in the enlarged view, the hinge assembly  504  includes a fifth roller element  514   e  (representing a roller element of the hinge assembly  504  that is nearest the second housing part  502   b ) that rotates with respect to a fifth spacer element  516   e  and a sixth spacer element  516   f . The clockwise rotation of the fifth roller element  514   e  causes an edge of the fifth roller element  514   e  to become pinched between a surface  528   e  of the fifth roller element  514   e  and a protrusion  542   f  of the sixth spacer element  516   f  such that additional clockwise rotation of the fifth roller element  514   e  is prevented. The clockwise rotation of the fifth roller element  514   e , combined with movement of the fifth spacer element  516   e , causes a protrusion  542   e  of the fifth spacer element  516   e  to engage a surface  528   f  of the fifth roller element  514   e  such that additional movement of the fifth spacer element  516   e  is prevented. As a result, the hinge assembly  504  includes at least a partial mechanical stop at the fifth roller element  514   e.    
       FIG. 19  illustrates an enlarged partial cross sectional view of the system  500  shown in  FIG. 18 , showing the hinge assembly  504  transitioned from the partially closed position to a closed position. As shown, the first housing part  502   a  is substantially positioned over the second housing part  502   b . In the closed position, additional protrusions of the spacer elements may be in contact with additional roller elements. For example, the first roller element  514   a  (representing a roller element of the hinge assembly  504  that is nearest the first housing part  502   a ) is positioned between and engaged with the first spacer element  516   a  and the second spacer element  516   b . As shown in the enlarged view, the clockwise rotation of the first roller element  514   a  causes an edge of the first roller element  514   a  to become pinched between a surface  528   a  of the first roller element  514   a  and a protrusion  542   c  of the second spacer element  516   b  such that additional clockwise rotation of the first roller element  514   a  is prevented. The clockwise rotation of the first roller element  514   a , combined with movement of the first spacer element  516   a , causes the second protrusion  542   b  of the first spacer element  516   a  to engage a surface  528   b  of the first roller element  514   a  such that additional movement of the second spacer element  516   b  is prevented. Further, as shown in  FIG. 19 , in the closed position, several protrusions of the spacer elements may engage a surface of a roller element, and the hinge assembly  504  is prevented from further movement. As a result, the hinge assembly  504  provides a mechanical stop using the protrusions of the spacer elements. 
       FIG. 20  illustrates an enlarged cross sectional view of an alternate embodiment of a system  600  having a hinge assembly  604  that includes spacer elements designed to contact one another, in accordance with some described embodiments. The hinge assembly  604  may include multiple spacer elements, such as a first spacer element  616   a , a second spacer element  616   b , a third spacer element  616   c , and a fourth spacer element  616   d . As shown, the first spacer element  616   a  may include a first dimension  652  at one end of the first spacer element  616   a , and may further include a second dimension  654  at another (opposing) end of the first spacer element  616   a . In some embodiments, the first dimension  652  is the same or substantially similar to the second dimension  654 . In the embodiment shown in  FIG. 20 , the first dimension  652  is less than the second dimension  654 . Also, the second spacer element  616   b , the third spacer element  616   c , and the fourth spacer element  616   d  (and any additional spacer elements) may include a dimensional relationship similar to that of the first spacer element  616   a.    
     As shown in  FIG. 20 , the system  600  is in the open position. However, when the system  600  transitions from the open position to a closed position, at least some of the spacer element may contact one another due in part to the dimensions of the spacer elements. For example,  FIG. 21  illustrates an enlarged cross sectional view of the system  600  shown in  FIG. 20 , further showing the system  600  in a closed position and several adjacent spacer elements in contact with one another. As shown in the enlarged view, the first spacer element  616   a  is in contact with the second spacer element  616   b , the second spacer element  616   b  is in contact with the third spacer element  616   c , and the third spacer element  616   c  is in contact with the fourth spacer element  616   d . Accordingly, the hinge assembly  604  can provide a mechanical stop based upon dimensional relationships of the spacer elements. 
       FIG. 22  illustrates an enlarged side view of an alternate embodiment of a system  700  having a hinge assembly  704  that includes spacer elements with magnetic elements, in accordance with some described embodiments. The magnetic elements (indicated as dotted lines) may be embedded in the spacer elements. Further, the magnetic elements may be embedded in their respective spacer elements such that an external magnetic field provided by the magnetic elements is at least partially external with respect to the spacer elements in which the magnetic element is embedded. Also, it should be noted that the spacer elements may be made from a material or materials that do not include a ferrous material so as to not affect the external magnetic fields. The hinge assembly  704  may include a roller element  714  positioned between a first spacer element  716   a  and a second spacer element  716   b . As shown in the enlarged view, the hinge assembly  704  includes a first magnetic element  756   a  in the first spacer element  716   a , and a second magnetic element  756   b  in the second spacer element  716   b . The magnetic polarity of the first magnetic element  756   a  may be opposite to that of the second magnetic element  756   b  such that when the first magnetic element  756   a  and the second magnetic element  756   b  are sufficiently close to one another, the first magnetic element  756   a  magnetically couples with the second magnetic element  756   b  to form a magnetic circuit, causing the first spacer element  716   a  to magnetically couple with the second spacer element  716   b . This will be shown below. As an example, the first magnetic element  756   a  may include a north facing polarity, or North Pole, and the second magnetic element  756   b  may include a south facing polarity, or South Pole, of such that the first magnetic element  756   a  is magnetically attracted to the second magnetic element  756   b . Also, although not labeled, the remaining spacer elements may include magnetic elements arranged in a similar relationship such that magnetic circuits may magnetically couple together adjacent spacer elements. Further, several spacer elements, including the first spacer element  716   a  and the second spacer element  716   b , may include two magnetic elements. As an example, in addition to the second magnetic element  756   b , the second spacer element  716   b  includes a third magnetic element  756   c.    
     In  FIG. 22 , the system  700  is in an open position. However, when the system  700  transitions to a closed position, the spacer elements move closer together causing some magnetic elements to magnetically couple to other magnetic elements. For example,  FIG. 23  illustrates an enlarged side view of the system  700  and hinge assembly  704  shown in  FIG. 22 , further showing the system  700  in a closed position and several adjacent spacer elements magnetically coupled with one another by way of magnetic elements. In the closed position, the first spacer element  716   a  is sufficiently close to the second spacer element  716   b  such that the first magnetic element  756   a  is magnetically coupled to the second magnetic element  756   b . Moreover, the magnetic coupling between the first magnetic element  756   a  and the second magnetic element  756   b  may draw the first spacer element  716   a  in contact with the second spacer element  716   b . Also, it should be noted that the magnetic circuit formed by the magnetic coupling between the first magnetic element  756   a  and the second magnetic element  756   b  provides a magnetic force strong enough to maintain an engagement (physical contact) between the first spacer element  716   a  and the second spacer element  716   b . However, a sufficient user-applied force can overcome the magnetic force and remove this engagement in order to return the system  700  to the open position. 
     Additional magnetic elements may form magnetic circuits to maintain an engagement between additional spacer elements. For example, the hinge assembly  704  may include a third spacer element  716   c  and a fourth spacer element  716   d . As shown, the third spacer element  716   c  can be coupled to the second spacer element  716   b  by way of a magnetic coupling between the third magnetic element  756   c  and a fourth magnetic element  756   d  (located in the third spacer element  716   c ). Also, the fourth spacer element  716   d  can be coupled to the third spacer element  716   c  by way of a magnetic coupling between a fifth magnetic element  756   e  (located in the third spacer element  716   c ) and a sixth magnetic element  756   f  (located in the fourth spacer element  716   d ). 
       FIGS. 24 and 25  show several static positions that can be maintained by the hinge assembly  704  using magnetic elements.  FIG. 24  illustrates an enlarged side view of the system  700  shown in  FIGS. 22 and 23 , showing a first set of adjacent spacer elements magnetically coupled with one another to retain the system  700  in a partially closed position. As shown, the fourth spacer element  716   d  is engaged with the fifth spacer element  716   e  and held together by a magnetic coupling between a seventh magnetic element  756   g  (located in the fourth spacer element  716   d ) and an eighth magnetic element  756   h  (located in the fifth spacer element  716   e ). 
       FIG. 25  illustrates an enlarged side view of the system shown in  FIG. 24 , showing a second set of adjacent spacer elements magnetically coupled with one another to retain the system  700  in a partially closed position. As shown, the third spacer element  716   c  is engaged with the fourth spacer element  716   d  and held together by a magnetic coupling between the fifth magnetic element  756   e  (located in the third spacer element  716   c ) and the sixth magnetic element  756   f  (located in the fourth spacer element  716   d ). Accordingly, the hinge assembly  704  can place the system  700  in various, static partially closed (or partially open) positions based upon magnetic couplings. Although not shown, other mechanical features previously described (such as the protrusions in  FIGS. 16-19 ) for a hinge assembly can places a system in various, static partially closed (or partially open) positions. 
       FIG. 26  illustrates a side view of an alternate embodiment of a system  800  having a hinge assembly  804  with extended spacer elements, in accordance with some described embodiments. As shown, the hinge assembly  804  may include a roller element  814  positioned between a first spacer element  816   a  and a second spacer element  816   b . The roller element  814  is grooved to receive a protruding feature  842   a  and a protruding feature  842   b  of the first spacer element  816   a  and the second spacer element  816   b , respectively. Further, the aforementioned protruding features may at least partially define mating surfaces for the first spacer element  816   a  and the second spacer element  816   b . The hinge assembly  804  places the system  800  in an open position, as shown in  FIG. 26 . However, in a closed position, the mating surfaces may engage each other. It should be noted that remaining roller and spacer elements may include similar relationships. 
       FIG. 27  illustrates a side view of the system  800  shown in  FIG. 26 , showing the system  800  in the closed position. In the closed position, the mating surfaces of the spacer elements contact each other to prevent further movement. For example, the first spacer element  816   a  engages the second spacer element  816   b  along respective mating surfaces. The first spacer element  816   a  and the second spacer element  816   b  may both rotate along the roller element  814  in order to engage each other. By using spacer elements with extended features that form mating surfaces, the hinge assembly  804  may not require engagement between mechanical interlocking between spacer elements and roller elements, and the manufacturing complexity of both the spacer elements and the roller elements may be reduced. 
       FIG. 28  illustrates a side view of an embodiment of a strap  920  formed from multiple materials designed to limit movement of the strap  920 , in accordance with some described embodiments. The strap  920  may be incorporated into one or more hinge assemblies described herein. As shown in the enlarged view, the strap  920  may include a first layer  921   a  and a second layer  921   b . Both the first layer  921   a  and the second layer  921   b  may lie outside a central axis line  922  passing through a center of the strap  920 . The first layer  921   a  may include a manufactured fiber made from a liquid crystal polymer material. The second layer  921   b  may include a metal, such as steel (as a non-limiting example). These may allow generally free movement of the strap  920  one direction, while limiting the strap  920  to movement in another (opposing) direction to a predetermined or predefined angle. This will be shown below. Also, although not described, a central material may be positioned between, and engaged with, the first layer  921   a  and the second layer  921   b.    
     The strap  920  may provide asymmetric stop capabilities designed to limit movement of a hinge assembly (not shown in  FIG. 28 ). As shown, the strap  920  is positioned at an angle  906 . However, the angle  906  may change. For example, in a closed position of a hinge assembly (not shown in  FIG. 28 ), the strap  920  bends to a first position  907   a  (shown as dotted lines). In an open position, the strap  920  bends to a second position  907   b  (shown as dotted lines) indicating that the strap  920  is flat, with opposing ends positioned at 180 degrees with respect to each other. The first layer  921   a  is designed to prevent the strap  920  from further movement. In other words, the first layer  921   a  is designed to prevent the strap  920  from bending beyond a 180-degree angle. In the second position  907   b , the tension in the strap  920 , and in particular, the first layer  921   a , increases sufficiently to prevent additional movement. However, the tension in the first layer  921   a  reduces as the strap  920  moves from the second position  907   b  to the first position  907   a . By providing a hinge assembly with the strap  920  (or multiple straps with similar properties), the hinge assembly may include a stop mechanism provided through the strap  920 , which may eliminate the need for mechanical stops by mechanical interlocking between spacer elements and roller elements. Although the first layer  921   a  permits bending to a 180-degree angle, other angles are possible. For example, in some embodiments (not shown in  FIG. 28 ), the first layer  921   a  permits bending to an angle approximately in the range of 90 to 135 degrees. 
       FIG. 29  illustrates an isometric view of an embodiment of a hinge assembly  1004 , showing straps positioned between segmented roller elements and spacer elements. As shown, the hinge assembly  1004  includes several roller elements and spacer elements. For example, the hinge assembly  1004  includes a first roller element  1014   a  and a first spacer element  1016   a , as well as a second roller element  1014   b  and a second spacer element  1016   b . The hinge assembly  1004  may include a first strap  1020   a  that separates the first roller element  1014   a  from the second roller element  1014   b , and also separates the first spacer element  1016   a  from the second spacer element  1016   b . The hinge assembly  1004  may further include a third roller element  1014   c  and a third spacer element  1016   c . The hinge assembly  1004  may include a second strap  1020   b  that separates the second roller element  1014   b  from the third roller element  1014   c , and also separates the second spacer element  1016   b  from the third spacer element  1016   c.    
     The first strap  1020   a  and the second strap  1020   b  may include any features described for the strap  920  (shown in  FIG. 28 ). Furthermore the first strap  1020   a  and the second strap  1020   b  may include a dimension (such as a height) that is the same as, or at least proximately similar to, a dimension of a spacer element or a roller element. For example, the first strap  1020   a  includes a dimension  1052  and a spacer element  1016   d  includes a dimension  1054  that is the same as, or at least proximately similar to, the dimension  1052 . It should be noted that the second strap  1020   b  includes the same dimensions as the first strap  1020   a , and the roller elements and spacer elements (including those not labeled) includes same dimensions as each other. In other words, the roller elements include approximately the same dimensions as each other, and the spacer elements include approximately the same dimensions as each other. 
     The hinge assembly  1004  may include additional straps passing through openings, or slots, of the roller elements and the spacer elements. As shown, the hinge assembly  1004  includes a third strap  1020   c  passing through roller elements and spacer elements, including the first roller element  1014   a  and the first spacer element  1016   a . The hinge assembly  1004  includes a fourth strap  1020   d  passing through roller elements and spacer elements, including the second roller element  1014   b  and the second spacer element  1016   b . The hinge assembly  1004  includes a fifth strap  1020   e  passing through roller elements and spacer elements, including the third roller element  1014   c  and the third spacer element  1016   c . These straps may be pulled in tension and may also maintain frictional engagement between their respective roller and spacer elements. Alternatively, or in combination, the third strap  1020   c , the fourth strap  1020   d , and the fifth strap  1020   e  may include circuitry, thereby providing a flexible circuit that routes signals between components carried by housing parts (not shown in  FIG. 29 ) that are coupled to the hinge assembly  1004 . Alternatively, or in combination, the third strap  1020   c , the fourth strap  1020   d , and the fifth strap  1020   e  may include a thermally conductive material (such as graphite, as a non-limiting example), thereby providing heat-dissipating properties that draw heat out of heat-generating components (such as displays and/or processor circuits, as non-limiting examples) carried by housing parts (not shown in  FIG. 29 ) that are coupled to the hinge assembly  1004 . 
       FIG. 30  illustrates an isometric view of an embodiment of a strap  1120  with an end piece  1141  coupled to the strap  1120 , in accordance with some described embodiments. The end piece  1141  may provide an insertion point into a housing part of a system (not shown in  FIG. 30 ) in order to couple the strap  1120  with the housing part. The end piece  1141  includes a flange design in which ends of the end piece  1141  extend beyond the ends of the strap  1120 . 
     The strap  1120  may include multiple layers of glass fibers, and the end piece  1141  may include carbon fiber. As shown the enlarged view, a layer of strap  1120  includes a layer with fibers aligned in one direction (as indicted by the dotted lines with arrows), while a layer of end piece  1141  includes fibers aligned in another direction (as indicted by the dotted lines with arrows). As shown in  FIG. 30 , the direction of the fibers in the strap  1120  is perpendicular with respect to the direction of the fibers in the end piece  1141 . In this regard, when strap  1120  is pulled in tension, the end piece  1141  can provide resistance to the pulling force. Although not shown, the end piece  1141  may include other materials, such as layered steel or a steel block. Also, the strap  1120  may include a first opening  1143   a  and a second opening  1143   b  designed to receive a first fastener and a second fastener, respectively, in order to secure an end of the strap  1120  (opposite the end piece  1141 ) to an additional housing part (not shown in  FIG. 30 ). Although not shown, the first opening  1143   a  and the second opening  1143   b  can be replaced by an end piece having any feature described for the end piece  1141 . 
     To further integrate the end piece  1141  with the strap  1120 , alternating layers of the end piece  1141  and the strap  1120  may be secured or bonded to each other. For example,  FIG. 31  illustrates a cross sectional view of the strap  1120  shown in  FIG. 30 , taken along line B-B, showing various layers of a composite that forms the end piece  1141  and the strap  1120 . As shown, the end piece  1141  may include a first layer  1151   a , or first ply, bonded to a first layer  1153   a , or first ply, of the strap  1120 . The first layer  1153   a  may bond to a second layer  1151   b  of the end piece  1141 . Also, the second layer  1151   b  of the end piece  1141  may bond to a second layer  1153   b  of the strap  1120 . Further, the second layer  1153   b  of the strap  1120  may bond to a third layer  1151   c  of the end piece  1141 . Additional layers for each of the strap  1120  and the end piece  1141  may be present. Also, the fibers in the layers for the strap  1120  may be aligned in a direction that is perpendicular with respect to the direction of the fibers in the end piece  1141 . 
       FIG. 32  illustrates a plan view of a system  1200 , showing several straps anchored into the system  1200 , in accordance with some described embodiments. The straps may include features described for the strap  1120  (shown in  FIGS. 30 and 31 ). For example, the system  1200  may include a hinge assembly  1204  that includes a first strap  1220   a  and a second strap  1220   b . The first strap  1220   a  and the second strap  1220   b  are secured to a first housing part  1202   a  and a second housing part  1202   b  of the system  1200 . As shown the enlarged view, the first strap  1220   a  includes a first end piece  1241   a  positioned in a first cavity  1255 , or pocket, in the first housing part  1202   a . The first cavity  1255  includes a size and shape such that the flange regions of the first end piece  1241   a  engage the first housing part  1202   a  within the first cavity  1255 , particularly when a pulling force is exerted on the first strap  1220   a  (in the direction of the arrow  1257 ). The tension from the pulling force can maintain the first end piece  1241   a  in engagement with the first housing part  1202   a , and fasteners and/or adhesives may not be needed. Also, the first strap  1220   a  is secured to the second housing part  1202   b  via fasteners  1243 . The second strap  1220   b  (designed for insertion into a second cavity of the first housing part  1202   a ) may include any features and may be secured with the first housing part  1202   a  and the second housing part  1202   b  in a similar manner as described for the first strap  1220   a.    
       FIG. 33  illustrates an isometric view of an alternate embodiment of a system  1300  having a hinge assembly  1304  coupled to a first housing part  1302   a  and a second housing part  1302   b , with the system  1300  in an open position, in accordance with some described embodiments. As shown, the hinge assembly  1304  may be partitioned into multiple segments, and accordingly, the hinge assembly  1304  may be referred to as a multi-segment hinge assembly.  FIG. 33  shows the hinge assembly  1304  including five segments. However, the number of segments may vary. In this regard, each segment may include multiple roller elements, and one or more straps. This will be shown below. Also, the first housing part  1302   a  and the second housing part  1302   b  may include any component(s) previously described for a first housing part and a second housing part, respectively. 
       FIG. 34  illustrates an isometric view of the system  1300  shown in  FIG. 33 , with the system  1300  transitioned to a closed position. The “closed position” may refer to the first housing part  1302   a  positioned substantially over the second housing part  1302   b , as shown in  FIG. 34 . The first housing part  1302   a  and the second housing part  1302   b  may include a first curved surface  1358   a  and a second curved surface  1358   b , respectively. In this regard, in the closed position, the hinge assembly  1304 , the first housing part  1302   a , and the second housing part  1302   b  define an opening  1360  that includes a circular shape. In instances when the first housing part  1302   a  and/or the second housing part  1302   b  includes as a display assembly (not shown in  FIG. 34 ), the opening  1360  may provide a space to receive an object (not shown in  FIG. 34 ) that can be used in conjunction with the display assembly. For example, the opening  1360  may receive a stylus or other tool that can be used to provide an input or command to the display assembly. Also, it should be noted that the roller elements and spacer elements of the hinge assembly  1304  may undergo synchronous motion similar to a manner previously described for a hinge assembly. 
       FIG. 35  illustrates an isometric view of a segment  1362  of the hinge assembly  1304 . The segment  1362  may refer to one of the five aforementioned segments of the hinge assembly  1304  shown in  FIG. 33 . As shown, the segment  1362  may include multiple roller elements, including a first roller element  1314   a  and a second roller element  1314   b . The segment  1362  may include several additional roller elements (not labeled). The segment  1362  may further include several spacer elements positioned between adjacent roller elements. For example, the segment  1362  may include a spacer element  1316  positioned between the first roller element  1314   a  and the second roller element  1314   b . The segment  1362  may include several additional spacer elements (not labeled). The segment  1362  may facilitate movement of the housing parts (shown in  FIGS. 33 and 34 ) by the roller elements rotating along concave surfaces of the spacer elements, similar to a manner previously described. The segment  1362  may further include a first housing attachment  1318   a  and a second housing attachment  1318   b  designed to couple or fasten to the first housing part  1302   a  (shown in  FIGS. 33 and 34 ) and the second housing part  1302   b  (shown in  FIGS. 33 and 34 ), respectively. The remaining segments of the hinge assembly  1304  (shown in  FIG. 33 ) may include any feature(s) described herein for the segment  1362 . 
     The segment  1362  may further include one or more straps that extend through the housing attachment elements, the roller elements, and the spacer elements. As shown in  FIG. 35 , the segment  1362  may include a first strap  1320   a , a second strap  1320   b , and a third strap  1320   c . These straps may include any material and provide any function previously described for a strap. Also each of the straps may provide a different purpose. For example, the first strap  1320   a  may be used by the segment  1362  to maintain engagement between the various elements, the second strap  1320   b  may be used to provide stiffness to the segment  1362  in order to maintain fixed positioned of the segment  1362 , and the third strap  1320   c  may be used as a flexible circuit in order to carry electrical communication to components in the first housing part  1302   a  and the second housing part  1302   b  (shown in  FIGS. 33 and 34 ). Alternatively, one of the first strap  1320   a , the second strap  1320   b , and the third strap  1320   c  may provide a counterbalance that can offset the force provided by the weight of a housing part (not shown in  FIG. 35 ) in either position, and may counterbalance the force of the housing part in generally any position of the first housing part. Alternatively, one of the first strap  1320   a , the second strap  1320   b , and the third strap  1320   c  may include a thermally conductive material, thereby providing heat-dissipating properties that draw heat out of heat-generating components (such as displays and/or processor circuits, as non-limiting examples) carried by housing parts (not shown in  FIG. 35 ) that are coupled to the hinge assembly  1304 . Referring again to  FIG. 33 , the hinge assembly  1304  may include multiple segments, with each segment having one or more straps (not shown in  FIG. 33 ). It should be noted that each strap may include any one of the functions described herein the straps shown in  FIG. 35 . 
     Alternatively, the first strap  1320   a , the second strap  1320   b , and the third strap  1320   c  may provide the segment  1362  with an increased stiffness, as opposed to the stiffness provided by a single strap. Each of the first strap  1320   a , the second strap  1320   b , and the third strap  1320   c  may be coupled to a tensioning element (shown later) designed to increase the frictional forces between the roller elements and the spacer elements. Further, when the additional segments (shown in  FIG. 33 ) include multiple straps used for stiffness, the hinge assembly  1304  may provide an increased stiffness for the system  1300  (shown in  FIGS. 33 and 34 ). In this regard, the straps may offset the forces associated with the weight the housing parts. This will be shown and discussed below. Also, the first strap  1320   a , the second strap  1320   b , and the third strap  1320   c  can be coupled to a first strap retention element  1364   a , a second strap retention element  1364   b , and a third strap retention element  1364   c , respectively, with the aforementioned strap retention elements acting as intermediaries between the straps and the tensioning elements (not shown). 
       FIG. 36  illustrates a cross sectional view of the system  1300  shown in  FIG. 35 , showing relative movement of the first housing part  1302   a  with respect to the second housing part  1302   b . As shown, the first strap  1320   a  extends into the first housing part  1302   a  and is secured to the first housing attachment  1318   a  that is positioned in and secured to the first housing part  1302   a . Also, the first strap  1320   a  and the first strap retention element  1364   a  may extend into the second housing part  1302   b , and the first strap retention element  1364   a  may be secured to a tensioning element  1370  by a fastener  1332 . The tensioning element  1370  may be separated from the first strap retention element  1364   a  by a stationary block  1374 . 
     As shown, the fastener  1332  is in threaded engagement with the first strap retention element  1364   a . Also, the tensioning element  1370  may expand to engage both the fastener  1332  and the stationary block  1374 . In this manner, the tensioning element  1370  may bias the head (not labeled) of the fastener  1332  in a direction away from the stationary block  1374 , thereby biasing the first strap retention element  1364   a  in a direction toward the stationary block  1374 . As a result of the biasing force, the tensioning element  1370  may provide a tension, or pulling force, to the first strap  1320   a  and increase the frictional forces between the roller elements and the spacer elements of the hinge assembly  1304 . However, by turning/rotating the fastener  1332 , the tensioning element  1370  may expand or contract and increase or decrease, respectively, the amount of pulling force applied to the first strap  1320   a . In this regard, the tensioning element  1370  and the fastener  1332  may be part of an adjustable tension system. As the system  1300  is in use over time, the roller elements and/or the spacer elements may wear down due to continued use. This may affect the user experience of the system  1300 . For example, the system  1300  may not open or close as smoothly, or the first housing part  1302   a , when moving from an initial position to a subsequent position (represented by a dotted line), may not remain fixed in the subsequent position according to a desired user setting. However, the tensioning element  1370  may be adjusted by the fastener  1332  and increase the tension applied to the first strap  1320   a , thereby increasing the frictional forces between the roller elements and the spacer elements, and the system  1300  may return to its original operation, and the first housing part  1302   a  may remain in a desired position relative to the second housing part  1302   b . Although not shown, the system  1300  may include a tensioning element, a fastener, and a stationary block for each strap used in the system  1300 . Accordingly, when the system  1300  includes five segments similar to the segment  1362  (shown in  FIG. 35 ) with three straps per segment, the system  1300  may include fifteen straps and fifteen tensioning elements. As a result, the system  1300  may rely more upon the stiffness of the straps, and less upon frictional forces between the roller elements and the spacer elements as the relatively high number of straps can hold and maintain the housing parts in various desired positions. However, should additional friction be required or desired, the tension applied to each of the straps can be adjusted using one or more of the aforementioned adjustable tension systems. 
     The straps may be used to counterbalance the housing parts. For example, when the first housing part  1302   a  is moved from an initial position to a subsequent position (represented by dotted lines), the force provided by the weight of the first housing part  1302   a  shifts. However, the stiffness provided by the straps can counterbalance the force provided by the weight of the first housing part  1302   a  in either position, and may counterbalance the force of the first housing part  1302   a  in generally any position of the first housing part  1302   a . Also, due in part to the known properties (such as material and thickness) of the straps, the roller elements, and the spacer elements, the amount of applied force the required to move the first housing part  1302   a  is more predicable to a user. Accordingly, the user of the system  1300  can more readily provide the amount of force required to overcome static friction exerted on first housing part  1302   a , and provide a kinetic friction moves the first housing part  1302   a , thereby providing a more predicable user experience may result. 
     Also, similar to prior embodiments, any forces applied to the roller elements (such as the first roller element  1314   a  and the second roller element  1314   b ) do not place the roller elements in torsion. In other words, the roller elements are not twisted for any position of the system  1300 . This may prevent unwanted wear on the roller elements and the spacer elements over time. Also, due to the roller elements not being twisted and placed in torsion, the roller elements store little or no energy. As a result, the roller elements do not attempt to redistribute the energy, in the form of a counterforce, to the first housing part  1302   a  and the second housing part  1302   b , and the first housing part  1302   a  and the second housing part  1302   b  due not undergo bowing or warping from the roller elements. In this regard, both the first housing part  1302   a  and the second housing part  1302   b  may remain generally flat. 
       FIG. 37  illustrates an isometric view of an alternate embodiment of a system  1400  having a hinge assembly  1404  coupled to a first housing part  1402   a  and a second housing part  1402   b , with the system  1400  in an open position, in accordance with some described embodiments. As shown, the hinge assembly  1404  may extend end-to-end, that is, the hinge assembly  1404  may extends to opposing ends of the first housing part  1402   a  (or alternatively, from opposing ends of the second housing part  1402   b ). Similar to prior embodiments, the hinge assembly  1404  may include multiple roller elements and multiple spacer elements. Also, the first housing part  1402   a  and the second housing part  1402   b  may include any component(s) previously described for a first housing part and a second housing part, respectively. 
       FIG. 38  illustrates an isometric view of the system  1400  shown in  FIG. 37 , with the system  1400  transitioned to a closed position. The “closed position” may refer to the first housing part  1402   a  positioned substantially over the second housing part  1402   b , as shown in  FIG. 38 . Similar to prior embodiments, the hinge assembly  1404  provides the system  1400  with flexibility and allows for several different positions, in addition to the open and closed positions. Also, it should be noted that the roller elements and spacer elements of the hinge assembly  1404  may undergo synchronous motion similar to a manner previously described for a hinge assembly. Further, the hinge assembly  1404  may allow any type of movement or rotation of the first housing part  1402   a  relative to the second housing part  1402   b  previously described. 
       FIG. 39  illustrates an isometric view of the system  1400  shown in  FIGS. 37 and 38 , with portions of the first housing part  1402   a  and the second housing part  1402   b  removed to show additional features of the hinge assembly  1404 . As shown, the hinge assembly  1404  may include multiple roller elements, including a first roller element  1414   a  and a second roller element  1414   b . The hinge assembly  1404  may include several additional roller elements (not labeled). The hinge assembly  1404  may further include several spacer elements positioned between adjacent roller elements. For example, the hinge assembly  1404  may include a spacer element  1416  positioned between the first roller element  1414   a  and the second roller element  1414   b . The hinge assembly  1404  may include several additional spacer elements (not labeled). The hinge assembly  1404  may facilitate movement of the first housing part  1402   a  and the second housing part  1402   b  by the roller elements rotating along concave surfaces of the spacer elements, similar to a manner previously described. 
     The hinge assembly  1404  may further include multiple straps. As shown, the hinge assembly  1404  includes a first strap  1420   a , a second strap  1420   b , and a third strap  1420   c . The straps may include any material or feature previously described for a strap. The first strap  1420   a , the second strap  1420   b , and the third strap  1420   c  include an end secured within an internal volume of the first housing part  1402   a . As indicated by the dotted lines, the first strap  1420   a , the second strap  1420   b , and the third strap  1420   c  pass through the roller elements and the spacer elements, so that an opposing end can be positioned in an internal volume of the second housing part  1402   b . The first strap  1420   a , the second strap  1420   b , and the third strap  1420   c  may couple to a first strap retention element  1464   a , a second strap retention element  1464   b , and a third strap retention element  1464   c , respectively. Also, the first strap retention element  1464   a , the second strap retention element  1464   b , and the third strap retention element  1464   c  couple to a first tensioning element  1470   a , a second tensioning element  1470   b , and a third tensioning element  1470   c  (shown in the enlarged view), respectively. The tensioning elements are designed to provide a pulling force to their respective straps, which may increase the frictional forces between the roller elements and the spacer elements. In some embodiments, the tensioning elements include a bevel washer. Each tension element may include a fastener (similar to a fastener  1432   c , in the enlarged view) that is in threaded engagement with a strap retention element. Accordingly, similar to a prior embodiment, each of the first tensioning element  1470   a , the second tensioning element  1470   b , and the third tensioning element  1470   c  can be part of an adjustable tensioning system. 
     The aforementioned tensioning elements may be separated from their respective strap retention elements by wall  1476  in the second housing part  1402   b . The wall  1476  may include openings or voids in locations corresponding to the tensioning elements. For example, as shown in the enlarged view, the wall  1476  includes an opening  1478  that allows the fastener  1432   c  to extend through the third tensioning element  1470   c  and through the wall  1476  (via the opening  1478 ). However, the opening  1478  is also small enough to prevent the third tensioning element  1470   c  from passing through the opening  1478 . In other words, the wall  1476  maintains the third tensioning element  1470   c  (as well as the remaining tensioning elements). 
       FIG. 40  illustrates a cross sectional view of the system  1400  shown in  FIGS. 37-39 , with the system  1400  in the closed position. The first housing part  1402   a  and the second housing part  1402   b  may be modified to mate or couple with the hinge assembly  1404 . For example, the first housing part  1402   a  may include a first curved surface  1458   a  having a convex surface that mates with a concave surface of a first spacer element  1416   a . Also, the second housing part  1402   b  may include a second curved surface  1458   b  having a convex surface that mates with a concave surface of a second spacer element  1416   b.    
     As shown in  FIG. 40 , the first strap  1420   a  is pulled in tension by way of the first tensioning element  1470   a . Also, a fastener  1432   a  is in threaded engagement with the first strap retention element  1464   a . In order to adjust the tension to the first strap  1420   a , the fastener  1432   a  can be rotated. Also, the first tensioning element  1470   a  may expand to engage both the fastener  1432   a  and the wall  1476 . In this manner, the first tensioning element  1470   a  may bias the head (not labeled) of the fastener  1432   a  in a direction away from the wall  1476 , thereby biasing the first strap retention element  1464   a  in a direction toward the wall  1476 . As a result of the biasing force, the first tensioning element  1470   a  may provide a tension, or pulling force, to the first strap  1420   a  and increase the frictional forces between the roller elements and the spacer elements of the hinge assembly  1404 . However, similar to a prior embodiment, the fastener  1432   a  can be turned/rotated, causing the first tensioning element  1470   a  to expand or contract to increase or decrease, respectively, the amount of pulling force applied to the first strap  1420   a . It should be noted that the second strap  1420   b  and the third strap  1420   c  (shown in  FIG. 39 ) may be placed in tension by their respective tensioning elements in a similar manner. 
     Also, as compared to other systems, the system  1400  shown in  FIGS. 37-40  may provide a low-profile system. In this regard, the components in the first housing part  1402   a  and the second housing part  1402   b  that are used with the hinge assembly  1404  may occupy less space. For example, the first tensioning element  1470   a  may include a smaller footprint as compared to that of the tensioning element  136  (shown in  FIG. 6 ). As a result, a height  1480  of the second housing part  1402   b  is significantly less than a comparable height of the second housing part  102   b  (in  FIG. 2 ) and the second housing part  1302   b  (in  FIG. 34 ). 
       FIG. 41  illustrates a cross sectional view of an alternate embodiment of a system  1500  in a closed position, showing the system having a hinge assembly  1504  with a strap  1520  extending along an outer region  1582  of the hinge assembly  1504 . As shown, the hinge assembly  1504  includes roller elements and spacer elements (not labeled) with openings located near the outer region  1582 . In the closed position, the tension exerted on the strap  1520  may provide a frictional force to roller elements and the spacer elements of the hinge assembly  1504 . However, when the system  1500  transitions to a partially open (or fully open) position, the tension exerted on the strap  1520  may change. For example, the tension exerted on the strap  1520  may increase, causing an increased friction force between the roller elements and the spacer elements. As a result, the system  1500  may provide a lower frictional force in the closed position (which may facilitate opening the system  1500 ), and a higher frictional force in the partially open (or fully open) position (which may facilitate maintaining the system  1500  in a desired position when the system is not closed). 
       FIG. 42  illustrates a cross sectional view of an alternate embodiment of a system  1600  in a closed position, showing the system  1600  having a hinge assembly  1604  with a strap  1620  extending along an inner region  1684  of the hinge assembly  1604 . As shown, the hinge assembly  1604  includes roller elements and spacer elements (not labeled) with openings located near the inner region  1684 . In the closed position, the tension exerted on the strap  1620  may provide a frictional force to roller elements and the spacer elements of the hinge assembly  1604 . However, when the system  1600  transitions to a partially open (or fully open) position, the tension exerted on the strap  1620  may change. For example, the tension exerted on the strap  1620  may decrease, causing a decreased friction between the roller elements and the spacer elements. As a result, the system  1600  may provide a lower frictional force in the partially open (or fully open) position (which may facilitate movement while in these positions), and a higher frictional force in the closed position (which may facilitate maintaining the closed position of the system  1600  until a user transitions the system  1600  to another position). 
     Hinge assemblies described herein may include several structural elements. For example,  FIG. 43  illustrates an exploded view of an embodiment of a hinge assembly  1704 , in accordance with some described embodiments. As shown, the hinge assembly  1704  may include several roller elements. For example, the hinge assembly  1704  includes a first roller element  1714   a , a second roller element  1714   b , a third roller elements  1714   c , and a fourth roller element  1714   d . Generally, the roller elements include a cylindrical shape, and accordingly, a circular cross section. However, other shapes (including oblong cross sections) are possible. The hinge assembly  1704  may further include several spacer elements, with a spacer element positioned between roller elements. For example, the hinge assembly  1704  includes a first spacer element  1716   a , a second spacer element  1716   b , and a third spacer element  1716   c . The spacer elements may be referred to as linking elements, as the spacer elements form a  nexus  between consecutive roller elements. Further, the spacer elements may include two concave surfaces, with each concave surface designed to engage the round/curved surface a roller element. The radius of the roller elements may be substantially similar to the radius of curvature of the concave surfaces of the spacer elements. However, in some embodiments, the radius of the roller elements differs from the radius of curvature of the concave surfaces of the spacer elements. This will be shown below. 
     The hinge assembly  1704  may further include several straps, with each strap passing through a through hole (not labeled), or opening, of the roller elements and the spacer elements. The hinge assembly  1704  includes a first strap  1720   a , a second strap  1720   b , and a third strap  1720   c . The straps may further couple or connect to housing parts, such as the first housing part  102   a  and the second housing part  102   b  (shown in  FIG. 1 ). The straps may include materials such as metal (including aluminum or copper), nylon, and/or fiber. Generally, the straps may include a material with flexible and deformable properties. 
     The straps may provide multiple functions. For example, at least one of the straps can maintain engagement between the roller elements and the spacer elements, when the hinge assembly  1704  is both stationary and in motion. Further, at least one of the straps may be used to limit or prevent movement of the hinge assembly  1704 , thereby limiting the hinge assembly  1704  such that a system is restricted to an open position (shown in  FIG. 1 ) or a closed position (shown in  FIG. 2 ). Moreover, some straps described herein are formed from a material known for relatively thermal conductivity (such as graphite). In this manner, the strap can transfer heat from a heat generating component in, for example, the second housing part  102   b  (shown in  FIG. 1 ) to the first housing part  102   a , thereby allowing the transferred to be convectively dissipated from the system  100 . However, it should be noted that the straps allow the hinge assembly  1704  to move freely between the two positions. Also, in some instances, each strap provides a different function. For example, the first strap  1720   a  may couple together two housing parts, thereby providing a force that maintains engagement between the roller elements and the spacer elements. The second strap  1720   b  may set limits to the movement of the hinge assembly  1704 , thereby limiting the angular position of one housing part relative to another housing part. The third strap  1720   c  may include a flexible circuit, which may form a communication channel for data and power between components in one housing part (such as a display) and another housing part (such as a circuit board, integrated circuits, and a battery). The features shown and described for the hinge assembly  1704  may be present in other hinge assemblies described herein. 
       FIG. 44  illustrates an isometric view of an alternate embodiment of a hinge assembly  1804 , showing the hinge assembly  1804  having segmented spacer elements, in accordance with some described embodiments. As shown, the hinge assembly  1804  includes a first roller element  1814   a  and a second roller element  1814   b , with a first spacer element  1816   a  positioned between, and engaged with, the first roller element  1814   a  and the second roller element  1814   b . The first roller element  1814   a  and the second roller element  1814   b  (as well as any additional roller elements of the hinge assembly  1804 ) may extend to opposing outer ends (or opposing edges) of the hinge assembly  1804 . However, the spacer elements may be segmented. For example, the first spacer element  1816   a  is separated from, but aligned with, a second spacer element  1816   b , which can be separate from, but aligned with, a third spacer element  1816   c.    
     The segmented configuration of the spacer elements may provide a specific function. For example, the first set of spacer elements (that includes the first spacer element  1816   a ) and the third set of spacer elements (that includes the third spacer element  1816   c ) may provide frictional engagement between the spacer elements and roller elements. The second set of spacer elements (that includes the second spacer element  1816   b ) may include mechanical stop features that limit the hinge assembly  1804  to predetermined positions. The mechanical stop features will be shown and described below. In order to maintain frictional engagement between some roller and spacer elements, the hinge assembly  1804  may include a first strap  1820   a  that passes through the first set of roller elements and spacer elements (that includes the first roller element  1814   a , the second roller element  1814   b , and the first spacer element  1816   a ), and a second strap  1820   b  that passes through the third set of roller elements and spacer elements (that includes the third spacer element  1816   c ). The straps may support frictional engagement between, and synchronous motion of, the roller and spacer elements. 
     To prevent relative lateral movement between roller and spacer elements, the hinge assembly  1804  may include several pins. For example, the enlarged view shows a partial cross sectional view of the first spacer element  1816   a  having a pin  1861  that extends into a cavity  1863   a  of the first roller element  1814   a  and into a cavity  1863   b  of the second roller element  1814   b . The pin  1861  is designed to limit or prevent relative movement of the roller elements with respect to the spacer elements, and vice versa, in order to maintain the first spacer element  1816   a , the first roller element  1814   a , and the second roller element  1814   b  with the hinge assembly  1804 . Although not shown, the spacer elements through which the first strap  1820   a  and the second strap  1820   b  pass may include a pin. 
       FIG. 45  illustrates a cross sectional view of the hinge assembly  1804  shown in  FIG. 44 , taken along line C-C, showing the middle spacer segments having protruding features that extending into cavities of the roller elements, in accordance with some described embodiments. As shown in the enlarged view, a spacer element  1816   e  includes a first protruding feature  1852   a  and a second protruding feature  1852   b , each of which may extend from a concave surface of the spacer element  1816   e  (with each concave surface designed to engage a roller element). Also, a third roller element  1814   c  includes a cavity  1846   a  that receives the first protruding feature  1852   a , and a fourth roller element  1814   d  includes a cavity  1846   b  that receives the second protruding feature  1852   b . The third roller element  1814   c  and the fourth roller element  1814   d  include an additional cavity (not labeled). The hinge assembly  1804  may include additional spacer elements (not labeled) with a protruding feature positioned in the additional cavities of roller elements. 
     The third roller element  1814   c  and the fourth roller element  1814   d  are capable of rotational movement (clockwise and counter-clockwise) with respect the spacer element  1816   e . However, the first protruding feature  1852   a  can prevent at least some rotational movement of the third roller element  1814   c , as the first protruding feature  1852   a  can engage the third roller element  1814   c  within the cavity  1846   a . Similarly, the second protruding feature  1852   b  can prevent at least some rotational movement of the fourth roller element  1814   d , as the second protruding feature  1852   b  can engage the fourth roller element  1814   d  within the cavity  1846   b.    
       FIG. 46  illustrates a side view of a roller element  1914  and a spacer element  1916 , showing a comparison between a radius  1924  of the roller element  1914  and a radius of curvature  1926  of the spacer element  1916 , in accordance with some described embodiments. As shown, the spacer element  1916  includes a concave surface  1928  that defines a receiving for the roller element  1914 . The concave surface  1928  also defines the radius of curvature  1926  of the spacer element  1916 . The radius of curvature  1926  of the spacer element  1916  may include a dimension that is substantially similar, or even greater than, the radius  1924  of the roller element  1914 . However, in the embodiment shown in  FIG. 46 , the radius of curvature  1926  of the spacer element  1916  is less than the radius  1924  of the roller element  1914 . This will be shown and discussed below. It should be noted that the spacer element  1916  includes an addition concave surface (not labeled) that may include any properties described for the concave surface  1928 . 
       FIG. 47  illustrates a side view of an embodiment of a hinge assembly  2004  that includes several roller elements and the spacer element, showing a relationship between roller elements and spacer elements, in accordance with some described embodiments. As shown, a roller element  2014  is positioned between, and engaged with, both a first spacer element  2016   a  and a second spacer element  2016   b . The first spacer element  2016   a  and the second spacer element  2016   b  have a similar size and shape. As shown in the first enlarged view  2030   a , the roller element  2014  engages the first spacer element  2016   a  at a first location  2032   a , or first engagement region, along a concave surface  2028  of the first spacer element  2016   a . The roller element  2014  may also engage the first spacer element  2016   a  at a second location  2032   b , or second engagement region, along the concave surface  2028 . 
     Due in part to the first spacer element  2016   a  having a concave surface  2028  that is smaller than a radius  2024  of the roller element  2014 , the round/curved surface of the roller element  2014  may not engage the concave surface  2028  at certain locations. For example, as shown in the second enlarged view  2030   b , the roller element  2014  is separated from the concave surface  2028  (of the first spacer element  2016   a ) by a gap  2034 . The gap  2034  may span from the first location  2032   a  to the second location  2032   b . However, the gap  2034  may vary. For instance, the gap  2034  may gradually increase at a location(s) further from the first location  2032   a  and the second location  2032   b . The first spacer element  2016   a  may include a symmetric design, and accordingly, the remaining convex surface (not labeled) of the first spacer element  2016   a  may be similar to the concave surface  2028 . Also, it should be noted that the relationship described herein between the roller element  2014  and the first spacer element  2016   a  may exist between other roller elements and spacer elements of the hinge assembly  2004 , such as the second spacer element  2016   b.    
       FIG. 48  illustrates a partial cross sectional view of an embodiment of a roller element  2114 , showing features of a through hole  2140  in the roller element, in accordance with some described embodiments. As shown, the through hole  2140  defines an opening that passes through the roller element  2114 . Further, the through hole  2140  may include surfaces of different geometries. For example, the through hole  2140  may include a first surface  2142   a  having a flat, or generally flat shape. The through hole  2140  may further include a second surface  2142   b  having a convex shape. The second surface  2142   b  may define a surface on which an aforementioned strap (not shown in  FIG. 48 ) may lie in certain positions or configurations of a portable computing device (not shown in  FIG. 48 ) that includes the roller element  2114 . This will be shown below. Also, although not shown, a roller element described herein may include a through hole with two flat surfaces, with each surface being similar to the first surface  2142   a  of the roller element  2114 . 
     Alternatively, although not shown, a roller element described herein may include a through hole with two convex surfaces, with each surface being similar to the second surface  2142   b  of the roller element  2114 . 
       FIG. 49  illustrates a cross sectional view of an embodiment of a system  2200  that includes a hinge assembly  2204  with a strap  2212  limiting movement of the roller elements and the spacer elements, in accordance with some described embodiments. As shown, the system  2200  includes a first housing part  2202   a  and a second housing part  2202   b  connected to a hinge assembly  2204 . The hinge assembly  2204  may include a first roller element  2214   a , a second roller element  2214   b , and a spacer element  2216  positioned between (and engaging) the first roller element  2214   a  and the second roller element  2214   b . The strap  2212  is connected to the first housing part  2202   a  and the second housing part  2202   b  and passes through the roller elements and the spacer elements of the hinge assembly  2204 . 
     In  FIG. 49 , the system  2200  is shown a closed position. As shown, each of the roller elements includes a convex surface on which the strap  2212  is positioned. Also, in the closed position, the strap  2212  may limit the first housing part  2202   a  from further rotational movement (in a direction toward the dotted line  2241 ) relative to the second housing part  2202   b . Accordingly, the strap  2212  may act as a stop mechanism that limits the roller elements and spacer elements of the hinge assembly  2204 . As shown in the enlarged view, the strap  2212  is engaged with surfaces of the first roller element  2214   a , the second roller element  2214   b , and the spacer element  2216 . As a result, the first roller element  2214   a , the second roller element  2214   b , and spacer element  2216  are prevented from additional two-dimensional movement, and the first roller element  2214   a  and the second roller element  2214   b  are prevented from further clockwise rotational movement. However, it should be noted that the strap  2212  may allow movement of the roller elements in the counter-clockwise direction, such that hinge assembly  2204  allows relative movement of the first housing part  2202   a  relative to the second housing part  2202   b , and allows the system  2200  to transition to an open position. 
       FIG. 50  illustrates a cross sectional view of an embodiment of a hinge assembly  2304  that includes a spacer element  2316  and roller elements, with the spacer element  2316  having a pin  2344  designed to limit movement of the roller elements, in accordance with some described embodiments. As shown, the hinge assembly  2304  includes a first roller element  2314   a  and a second roller element  2314   b , both of which engage the spacer element  2316 . Also, The first roller element  2314   a  includes a cavity  2346   a  and the second roller element  2314   b  includes a cavity  2346   b , with the pin  2344  positioned in the cavity  2346   a  and the cavity  2346   b . A “cavity” refers to a void or space in the roller elements. The first roller element  2314   a  and the second roller element  2314   b  include an additional cavity (not labeled). The hinge assembly  2304  may include additional spacer elements (not shown in  FIG. 50 ) with a pin positioned in the additional cavities. 
     The first roller element  2314   a  and the second roller element  2314   b  are capable of rotational movement (clockwise and counter-clockwise) with respect the spacer element  2316 . However, the pin  2344  (secured to the spacer element  2316 ) limits at least some rotational movement of the roller elements. For example, a first dotted line  2348  represents clockwise movement of the first roller element  2314   a  until the first roller element  2314   a  engages the pin  2344 , and a second dotted line  2350  represents clockwise movement of the second roller element  2314   b  until the second roller element  2314   b  engages the pin  2344 . Accordingly, the pin  2344  may limit rotational movement of the roller elements. It should be noted that the pin  2344  may limit rotational counter-clockwise movement of both the first roller element  2314   a  and the second roller element  2314   b.    
       FIG. 51  illustrates a cross sectional view of an embodiment of a hinge assembly  2404  that includes a spacer element  2416  and roller elements, with the spacer element  2416  having protruding features designed to limit movement of the roller elements, in accordance with some described embodiments. As shown, the spacer element  2416  includes a first protruding feature  2452   a  and a second protruding feature  2452   b , each of which may extend from a concave surface of the spacer element  2416  (with each concave surface designed to engage a roller element). 
     In some embodiments, the first protruding feature  2452   a  and the second protruding feature  2452   b  define a protrusion. In the embodiment shown in  FIG. 51 , the first protruding feature  2452   a  and the second protruding feature  2452   b  define a dovetail protrusion. As shown in the enlarged view, the first protruding feature  2452   a  includes multiple tapered regions. The second protruding feature  2452   b  may include similar features as that of the first protruding feature  2452   a . Also, the first roller element  2414   a  includes a cavity  2446   a  that receives the first protruding feature  2452   a , and the second roller element  2414   b  includes a cavity  2446   b  that receives the second protruding feature  2452   b . The first roller element  2414   a  and the second roller element  2414   b  include an additional cavity (not labeled). The hinge assembly  2404  may include additional spacer elements (not shown in  FIG. 51 ) with a protruding feature positioned in the additional cavities. 
     The first roller element  2414   a  and the second roller element  2414   b  are capable of rotational movement (clockwise and counter-clockwise) with respect the spacer element  2416 . However, the first protruding feature  2452   a  can prevent at least some rotational movement of the first roller element  2414   a , as the first protruding feature  2452   a  can engage the first roller element  2414   a  within the cavity  2446   a . Similarly, the second protruding feature  2452   b  can prevent at least some rotational movement of the second roller element  2414   b , as the second protruding feature  2452   b  can engage the second roller element  2414   b  within the cavity  2446   b.    
       FIG. 52  illustrates a cross sectional view of an embodiment of a hinge assembly  2504  that includes a spacer element  2516  and roller elements, with the spacer element  2516  having an enhanced protruding features designed to limit movement of the roller elements, in accordance with some described embodiments. As shown, the hinge assembly  2504  includes a first roller element  2514   a  and a second roller element  2514   b , both of which engage the spacer element  2516 . Also, the first roller element  2514   a  and the second roller element  2514   b  are capable of rotational movement (clockwise and counter-clockwise) with respect the spacer element  2516 . The spacer element  2516  may include a first protruding feature  2552   a  and a second protruding feature  2552   b . The first protruding feature  2552   a  and the second protruding feature  2552   b  may define a dovetail protrusion. Further, the first protruding feature  2552   a  and the second protruding feature  2552   b  may be angled. In other words, the first protruding feature  2552   a  and the second protruding feature  2552   b  are positioned on their respective concave surfaces at some non-zero angle with respect to a horizontal line. Also, the first roller element  2514   a  includes a cavity  2546   a  that receives the first protruding feature  2552   a , and the second roller element  2514   b  includes a cavity  2546   b  that receives the second protruding feature  2552   b . The first roller element  2514   a  and the second roller element  2514   b  include an additional cavity (not labeled). The hinge assembly  2504  may include additional spacer elements (not shown in  FIG. 52 ) with a protruding feature positioned in the additional cavities. 
     The first roller element  2514   a  and the second roller element  2514   b  are capable of rotational movement (clockwise and counter-clockwise) with respect the spacer element  2516 . However, the first protruding feature  2552   a  can prevent at least some rotational movement of the first roller element  2514   a , as the first protruding feature  2552   a  can engage the first roller element  2514   a  within the cavity  2546   a . Similarly, the second protruding feature  2552   b  can prevent at least some rotational movement of the second roller element  2514   b , as the second protruding feature  2552   b  can engage the second roller element  2514   b  within the cavity  2546   b.    
       FIGS. 50-52  illustrate hinge assemblies with a single spacer element and a pair of roller elements. It should be noted that the hinge assemblies shown and described in  FIGS. 50-52  may include several additional roller elements and spacer elements, similar to other hinge assemblies described herein. 
       FIG. 53  illustrates a cross sectional view of an embodiment of a system  2600  in an open position, showing a dovetail configuration of a spacer element  2616  limiting movement of roller elements in the open position, in accordance with some described embodiments. As shown, the system  2600  includes a first housing part  2602   a  connected to a second housing part  2602   b  by a hinge assembly  2604 , with the hinge assembly  2604  having spacer elements, including the spacer element  2616 , and several roller elements, including a first roller element  2614   a  and a second roller element  2614   b . The first roller element  2614   a  includes a cavity  2646   a  and the second roller element  2614   b  includes a cavity  2646   b . Also, the spacer element  2616  includes a first protruding feature  2652   a  positioned in the cavity  2646   a , and a second protruding feature  2652   b  positioned in the cavity  2646   b.    
     The hinge assembly  2604  is designed to limit rotation and define the open position of the system  2600 . For example, as shown in the enlarged view, the first protruding feature  2652   a  engages a surface of the first roller element  2614   a  within the cavity  2646   a , and the second protruding feature  2652   b  engages a surface of the second roller element  2614   b  within the cavity  2646   b , thereby preventing further movement of the hinge assembly  2604 . The remaining roller elements and spacer elements (not labeled) may undergo a similar relationship. 
       FIG. 54  illustrates a side sectional view of the system  2600  shown in  FIG. 53 , showing the system  2600  transition from the open position to a closed position. As shown, the first housing part  2602   a  is positioned over the second housing part  2602   b , and the housing parts are parallel (or least approximately parallel) in the closed position. As shown in the enlarged view, the first protruding feature  2652   a  engages a different surface of the first roller element  2614   a  within the cavity  2646   a , as compared to the surface of the first roller element  2614   a  in the open position (shown in  FIG. 40 ). Also, the second protruding feature  2652   b  engages a different surface of the second roller element  2614   b  within the cavity  2646   b , as compared to the surface of the second roller element  2614   b  in the open position (shown in  FIG. 40 ). As a result, the spacer element  2616  prevents further respective movement of the first roller element  2614   a  and the second roller element  2614   b  in the closed position. The remaining roller elements and spacer elements (not labeled) may undergo a similar relationship. Accordingly, spacer elements can limit movement of the hinge assembly  2604  for both the open and closed positions. 
       FIG. 55  illustrates a side view of an embodiment of a hinge assembly  2704 , showing a spacer element  2716  having a protruding feature that is off-center on a concave surface of the spacer element  2716 , in accordance with some described embodiments. As shown, the spacer element  2716  is positioned between a first roller element  2714   a  and a second roller element  2714   b . The spacer element  2716  includes a first protruding feature  2752   a  and a second protruding feature  2752   b , each of which may extend from a concave surface of the spacer element  2716  (with each concave surface designed to engage a roller element). As shown, the first protruding feature  2752   a  is centered, or at least approximately, centered on a concave surface of the spacer element  2716 . However, the second protruding feature  2752   b  is off-center on another concave surface of the spacer element  2716 . As a result, the relative degree of rotation between the first roller element  2714   a  and the second roller element  2714   b  may differ. This may cause the hinge assembly  2704  to cease movement and cause the positioning a system (not shown in  FIG. 55 ) to differ, as compared to prior embodiments, and different relative positions between housing parts (not shown in  FIG. 55 ) may be achieved. 
       FIG. 56  illustrates a side view of an embodiment of a hinge assembly  2804 , showing the spacer element having multiple protruding features that are off-center on concave surfaces of the spacer element, in accordance with some described embodiments. As shown, the spacer element  2816  is positioned between a first roller element  2814   a  and a second roller element  2814   b . The spacer element  2816  includes a first protruding feature  2852   a  and a second protruding feature  2852   b , each of which may extend from a concave surface of the spacer element  2816  (with each concave surface designed to engage a roller element). As shown, both the first protruding feature  2852   a  and the second protruding feature  2852   b  are off-center on their respective concave surfaces of the spacer element  2816 . As a result, the relative degree of rotation between the first roller element  2814   a  and the second roller element  2814   b  may again differ. This may cause the hinge assembly  2804  to cease movement and cause the positioning a system (not shown in  FIG. 56 ) to differ, as compared to prior embodiments, and different relative positions between housing parts (not shown in  FIG. 56 ) may again be achieved. 
       FIG. 57  illustrates an isometric view of a modular spacer element  2916  used with a hinge assembly (not shown in  FIG. 57 ), in accordance with some described embodiments. As shown, the modular spacer element  2916  may include a first protruding feature  2952   a  and a second protruding feature  2952   b , similar to prior embodiments. However, the modular spacer element  2916  is designed for removal, if desired, from a hinge assembly (not shown in  FIG. 57 ). This provides a hinge assembly with added flexibility. For example, when the modular spacer element  2916  is installed in a hinge assembly, an open position and/or a closed of a system (not shown in  FIG. 57 ) may be limited to a defined angle. However, when the modular spacer element  2916  is removed from the hinge assembly, the angles defined by the open and closed positions of the system may change. 
       FIG. 58  illustrates an isometric view of an embodiment of a system  2900  that includes a hinge assembly  2904  with modular spacer elements, in accordance with some described embodiments. As shown, the system  2900  includes a first housing part  2902   a  connected to a second housing part  2902   b  by the hinge assembly  2904 . The modular spacer element  2916  is integrated with the hinge assembly  2904 . Also, a second modular spacer element  2916   b  can be integrated with the hinge assembly  2904 . 
     As shown in the enlarged view, the modular spacer element  2916  is engaged with a first roller element  2914   a  and a second roller element  2914   b  of the hinge assembly  2904 . Further, the protruding features of the modular spacer element  2916  are engaged with the first roller element  2914   a  and the second roller element  2914   b  within their respective cavities. Although not shown, the protruding features of the second modular spacer element  2916   b  are engaged with the first roller element  2914   a  and the second roller element  2914   b  within their respective cavities. As a result, the system  2900  is in the open position, and the first housing part  2902   a  will not rotate further away from the second housing part  2902   b . However, when the modular spacer element  2916  and the second modular spacer element  2916   b  are removed from the hinge assembly  2904 , the first housing part  2902   a  is now able to rotate further away from the second housing part  2902   b . In some instances, the first housing part  2902   a  can be positioned co-planar with respect to the second housing part  2902   b.    
       FIG. 59  illustrates a cross sectional view of an embodiment of a system  3000  that includes a hinge assembly  3004  and a strap  3020 , showing the system  3000  transitioning from a closed position to an open position, in accordance with some described embodiments. As shown, the strap  3020  is centrally located in the hinge assembly  3004 . In other words, the strap  3020  extends through a center of each of the components of the hinge assembly  3004 . When the system  3000  transitions from one position to another position, the effective length of the strap  3020  changes as forces, such as shear stress, applied to the strap  3020  change. In some instances, the resultant effective length of the strap  3020  reduces when the system  3000  is in the open position due to a force that pulls the strap  3020  into the hinge assembly  3004 . As a result, the strap  3020  is pulled in tension. Over time, the strap  3020  may break down due the pulling forces by transitioning between the open and closed positions. 
       FIG. 60  illustrates a graph  3101  of effective length of a strap versus angle. The x-axis represents an angle between a first housing part and a second housing part of a system. For example, when the angle is 0 degrees, the system is in a closed position and the first housing part is positioned over the second housing part. When the angle is 180 degrees, the system is in an open position and both the first housing part and the second housing part lie flat in the same plane. 
     For each plot in the graph  3101 , the strap may include the same length prior to any forces acting on the strap. A first plot  3103  represents a system with a strap that is centrally located in, or positioned in the middle of, a hinge assembly of the system. As shown, the effective length of the strap is 20.25 millimeters (“mm”) in the closed position, while the effective length of the strap is approximately 19.8 mm in the open position. Accordingly, when the strap is centrally located in the hinge assembly, the first plot  3103  shows the effective length decreases when the system transitions from the closed position to the open position, and tension on the strap may pull the strap into the hinge assembly. 
     However, by re-positioning the strap in a different location in the hinge assembly, the effective length changes. For example, a second plot  3105  represents a system with a strap that is biased toward (or positioned along) an internal portion of a hinge assembly of the system. As shown, the effective length of the strap is 19.25 mm in the closed position, while the effective length of the strap is approximately 19.8 mm in the open position. Accordingly, when the strap is biased toward the internal portion of the hinge assembly, the second plot  3105  shows the effective length increases when the system transitions from the closed position to the open position, and tension on the strap may pull the strap out of the hinge assembly. 
       FIG. 61  illustrates a cross sectional view of an embodiment of a system  3200  in a closed position, showing the system  3200  with a strap  3220  that is offset from respective centers of rolling elements and spacer elements that form a hinge assembly  3204 , in accordance with some described embodiments. As shown, the strap  3220  is biased toward an internal portion  3251 , or internal region, of the system  3200 , with respect to a centerline  3254  (shown as a dotted line) extending through the center of the hinge assembly  3204 . 
     The system  3200  includes a first housing part  3202   a  and a second housing part  3202   b  coupled to the hinge assembly  3204 . As shown, the strap  3220  is secured to the second housing part  3202   b  by a pin  3256 . However, the strap  3220  is not secured to the first housing part  3202   a . Rather, the first housing part  3202   a  includes a stop mechanism  3258  designed to prevent or limit movement of the strap  3220  in some configurations. It should be noted that in some embodiments (not shown), the strap  3220  can be secured to the first housing part  3202   a  by the pin  3256  and the stop mechanism  3258  can be positioned in the second housing part  3202   b.    
       FIG. 62  illustrates a cross sectional view of the system  3200  shown in  FIG. 61 , showing the system  3200  in an open position and the strap  3220  engaging the stop mechanism  3258 . In the open position, the stop mechanism  3258  prevents further movement of the strap  3220  into the first housing part  3202   a . The stop mechanism  3258  accommodates a change in the effective length of the strap  3220 , while also limiting movement of the strap  3220  in a certain direction. Subsequent to an assembly operation of the hinge assembly  3204  with the first housing part  3202   a  and the second housing part  3202   b , the stop mechanism  3258  can be adjusted or tuned to set the location at which the strap  3220  will engage the stop mechanism  3258  and be limited from further movement. 
       FIG. 63  illustrates an isometric view of an alternate embodiment of a system  3300  having recesses designed to accommodate a hinge assembly  3304 , in accordance with some described embodiments. The system  3300  may include several features described herein for a system. As shown, the system  3300  includes a first housing part  3302   a  and a second housing part  3302   b . The system  3300  may further include a hinge assembly  3304  coupled to the first housing part  3302   a  and the second housing part  3302   b . Also, the first housing part  3302   a  may include a first recess  3362   a  and the second housing part  3302   b  may include a second recess  3362   b . The recesses are designed to receive the hinge assembly  3304 . This will be shown and described below. 
       FIG. 64  illustrates a partial cross sectional view of the system  3300  shown in  FIG. 48 , showing the system  3300  in an open position. As shown, the hinge assembly  3304  may be positioned, or at least partially positioned, in the first recess  3362   a  of the first housing part  3302   a  and in the second recess  3362   b  of the second housing part  3302   b . Also, the hinge assembly  3304  includes several spacer elements and roller elements. For example, the hinge assembly  3304  includes a spacer element  3316 . In some instances, the spacer element  3316  may extend (as shown in the dotted lines) from the hinge assembly  3304  and define a support for the system  3300 . Further, when the spacer element  3316  engages a surface  3366  (which may include a table or desk, as non-limiting examples), the spacer element  3316  may elevate the system  3300  (and in particular, the second housing part  3302   b ) away from the surface  3366 . 
       FIG. 65  illustrates a partial cross sectional view of the system  3300  shown in  FIG. 48 , showing the system  3300  in a closed position. As shown, the hinge assembly  3304  is positioned in the first recess  3362   a  such that the hinge assembly  3304  is flush, or co-planar, with respect to an outer perimeter of the first housing part  3302   a . Also, the hinge assembly  3304  is positioned in the second recess  3362   b  such that the hinge assembly  3304  is flush, or co-planar, with respect to an outer perimeter of the second housing part  3302   b . As a result, the system  3300  may include a compact design with a hinge assembly  3304  that is functional with several moving parts, while also providing an aesthetic design. 
       FIG. 66  illustrates a plan view of an alternate embodiment of a strap  3420  that includes several blocks, in accordance with some described embodiments. As shown, the strap  3420  includes several blocks, such as a first block  3466   a  and a second block  3466   b . Several additional blocks (not labeled) are shown. The strap  3420  may include a through hole, or opening, for each block. For example, the strap  3420  includes a through hole  3468  through which a portion of the first block  3466   a  passes. The blocks may limit or prevent some movement of the strap  3420 . In this regard, when the strap  3420  is integrated into a hinge assembly (not shown in  FIG. 66 ), the blocks may limit or prevent some movement of the hinge assembly. 
       FIG. 67  illustrates a cross sectional view of the strap shown in  FIG. 66 , showing the strap  3420  in a bent configuration. When the strap  3420  is in the bent configuration, the strap  3420  may resemble a configuration of a system (not shown in  FIG. 67 ) in a closed position. As shown, the blocks are separated from each other when the strap  3420  is in the bent configuration. 
       FIG. 68  illustrates a cross sectional view of the strap  3420  shown in  FIG. 66 , showing the strap  3420  in a flat configuration. When the strap  3420  is in the flat configuration, the strap  3420  may resemble a configuration of a system (not shown in  FIG. 53 ) in an open position. As shown, the blocks are engaged each other when the strap  3420  is in the flat configuration to limit movement of the strap  3420 . For example, the first block  3466   a  is engaged with the second block  3466   b . Although not shown, the blocks may engage each to limit the movement of the strap  3420  to different angles. For example, the blocks may engage each to limit the movement of the strap  3420  to an angle approximately in the range of 90-135 degrees such that when integrated into a system, the housing parts (not shown in  FIG. 68 ) are limited to an angular position with respect to each other approximately in the range of 90-135 degrees. The blocks may include different sizes and shapes in or achieve a desired angle. 
       FIGS. 69-82  show various embodiments of roller elements and spacer elements that may be integrated into a hinge assembly described herein.  FIGS. 69-82  may also show and describe methods for forming a roller element or a spacer element. Although  FIGS. 69-82  may show and describe either a roller element or a spacer element, the processes and configurations may be applied to a spacer element or a roller element, respectively. 
       FIG. 69  illustrates a cross sectional view of an embodiment of a roller element  3514 , showing the roller undergoing a cutting operation by a tool  3571 , in accordance with some described embodiments. The tool  3571  may include an electrical discharge machining (“EDM”) tool. Alternatively, the tool  3571  may include an electrochemical machining (“ECM”) tool. Also, in some embodiments, the tool  3571  includes a T-cutting tool. As shown, the tool  3571  may cut partially through the roller element  3514 . 
       FIG. 70  illustrates a cross sectional view of the roller shown in  FIG. 69 , showing the roller element  3514  further undergoing the cutting operation. The tool  3571  may again cut partially through the roller element  3514 . Further, the partial cut through the roller element  3514  by the tool  3571  is aligned with the initial partial cut (shown in  FIG. 69 ). 
       FIG. 71  illustrates a cross sectional view of the roller element  3514  shown in  FIG. 70 , showing the roller element  3514  subsequent to the cutting operation. As shown, the cutting operation through the roller element  3514  forms a through hole  3540  that defines an opening that passes through the roller element  3514 . Further, the through hole  3540  may include surfaces of different geometries. For example, the through hole  3540  may include a first surface  3528   a  having a flat, or generally flat shape. The through hole  3540  may further include a second surface  3528   b  having a convex shape. The second surface  3528   b  may define a surface on which an aforementioned strap (not shown in  FIG. 71 ) may lie in certain positions or configurations of a portable computing device (not shown in  FIG. 71 ) that includes the roller element  3514 . 
       FIG. 72  illustrates an isometric view of an embodiment of a roller element  3614 , showing an insert  3672  designed for integration with the roller element  3614 , in accordance with some described embodiments. As shown, the roller element  3614  includes a through hole  3674  having a size and shape in accordance with the insert  3672 . The insert  3672  may include a pre-molded or pre-fabricated part. The insert  3672  may include a metal or a hardened plastic material, as non-limiting examples. Further, the insert  3672  includes a through hole  3640  designed to receive a strap (not shown in  FIG. 72 ). The through hole  3640  may include a convex and a flat surface. This will be shown below. In this manner, the cutting operation used to form the through hole  3674  may be less complex, as compared to prior embodiments, as the through hole  3640  is formed to a specification prior to inserting the insert  3672  into the through hole  3674  of the roller element  3614 . 
       FIG. 73  illustrates a cross sectional view of the roller element  3614  shown in  FIG. 72 , showing the insert  3672  positioned in the roller element  3614 . The insert  3672  may be adhesively secured, welded or molded to the roller element  3614  at the through hole  3674 . The through hole  3640  of the insert  3672  may include a first surface  3628   a  having a flat shape, and a second surface  3628   b  having a convex shape. The second surface  3628   b  may define a surface on which strap (not shown in  FIG. 73 ) may lie in certain positions or configurations of a portable computing device (not shown in  FIG. 73 ) that includes the roller element  3614 . 
       FIG. 74  illustrates a cross sectional view of an embodiment of a roller element  3714 , showing the roller element  3714  having an insert  3772  that defines a through hole  3740 , in accordance with some described embodiments. The insert  3772  may be formed through a molding operation to the roller element  3714 . The molding operation may include an over molding or an injection molding operation, as non-limiting examples. Also, as shown in  FIG. 74 , the roller element  3714  is defined by a tube that is generally hollow, with the exception of the insert  3772 . The hollow tube may reduce the material used to form the roller element  3714 , which may reduce the costs and overall weight of a hinge assembly (not shown in  FIG. 74 ) that includes the roller element  3714 . The insert  3772  may include a through hole  3740  that provides a path through which a strap (not shown in  FIG. 74 ) is positioned. As shown, the through hole  3740  may include a first surface  3728   a  that is generally flat or planar, as well as a second surface  3728   b  that includes a convex shape. 
       FIG. 75  illustrates a cross sectional view of an embodiment of a roller element  3814 , showing the roller element  3814  having an insert  3872  that defines a single surface for a strap, in accordance with some described embodiments. The insert  3872  can be formed through a molding operation to the roller element  3814 . The molding operation may include an over molding or an injection molding operation, as non-limiting examples. As shown in  FIG. 75 , the roller element  3814  is defined by a tube that is generally hollow, with the exception of the insert  3872 . In order to further reduce the weight of the roller element  3814 , the insert  3872  can be molded in a manner that provides a single surface for a strap (not shown in  FIG. 75 ). As shown, the insert  3872  may include surface  3828  that includes a convex shape. As a result, the insert  3872  provides a more simplified insert with less material (and less associated weight), as compared to the insert  3872 , as compared to the insert  3772  shown in  FIG. 74 . 
     Also, when the insert  3872  (and in some instances, both the insert  3872  and the roller element  3814 ) is formed from a non-metal, a wireless component  3874  can be embedded in the insert  3872 . The wireless component  3874  may include an antenna or some other wireless hardware. This may provide a portable electronic device (not shown in  FIG. 75 ) that includes the roller element  3814  with wireless communication without occupying space in the portable electronic device, thereby providing additional space in the portable electronic device for other components. 
       FIG. 76  illustrates an isometric view of an embodiment of a roller element  3914 , showing the roller element  3914  formed by coupling two structures together along their respective longitudinal axes, in accordance with some described embodiments. The longitudinal axis is defined along the x-axis in the Cartesian coordinate system. The roller element  3914  may include a first part  3976   a  coupled with a second part  3976   b . As shown, the first part  3976   a  may include a recess  3940  such that when the first part  3976   a  is coupled with the second part  3976   b , the recess  3940  forms a through hole that can accommodate a strap (not shown in  FIG. 76 ). By forming a roller element  3914  using the first part  3976   a  and the second part  3976   b , the roller element  3914  can be made by two different materials, such as a metal and a non-metal. Also, by forming the recess  3940  prior to assembling the first part  3976   a  with the second part  3976   b , the recess  3940  can be made through different cutting means, which may simplify the cutting operation. Also, the second part  3976   b  may include a convex shape (similar to prior embodiments) at least in a location corresponding to the recess  3940 , in order to provide a convex shape at the recess  3940 . 
       FIG. 77  illustrates an isometric view of an embodiment of a roller element  4014 , showing the roller element  4014  formed by coupling a structure into an opening of another structure, in accordance with some described embodiments. The roller element  4014  may include a first part  4076   a  that includes an opening (not labeled) to receive a second part  4076   b . When the second part  4076   b  is positioned in the first part  4076   a  (as shown in  FIG. 77 ), a recess  4040  results and defines a through hole that can accommodate a strap (not shown in  FIG. 77 ). By forming a roller element  4014  using the first part  4076   a  and the second part  4076   b , the use of materials can be disproportionate. For example, a greater amount of material used to form the first part  4076   a  is used as compared to the second part  4076   b . By limiting the use of the material of the second part  4076   b , the cost of materials can be reduced when the material(s) used to form the second part  4076   b  is relatively high. Also, the weight of materials can be reduced when the material(s) used to form the second part  4076   b  is relatively high. 
       FIG. 78  illustrates an exploded view of an embodiment of a roller element  4114 , showing the roller element  4114  prior to an assembly operation, in accordance with some described embodiments. As shown, the roller element  4114  may include several parts that can be assembled together. For example, the roller element  4114  may include a first part  4176   a  and a second part  4176   b . The roller element  4114  may further include multiple central parts  4176   c . When assembled with the first part  4176   a  and the second part  4176   b , the multiple central parts  4176   c  are spaced apart from each other to define several through holes, each of which is capable of receiving a strap (not shown in  FIG. 78 ). Also, the second part  4176   b  may include a surface  4128  that defines a convex shape to accommodate the straps. 
       FIG. 79  illustrates an isometric view of the roller element  4114  shown in  FIG. 78 , showing the roller element  4114  subsequent to an assembly operation. As shown, the multiple central parts  4176   c  are assembled with the first part  4176   a  and the second part  4176   b . The multiple central parts  4176   c  are spaced apart from each other such that the roller element  4114  includes a first through hole  4140   a , a second through hole  4140   b , and a third through hole  4140   c . By using the multiple central parts  4176   c , the first through hole  4140   a , the second through hole  4140   b , and the third through hole  4140   c  need not be cut out of the roller element  4114  by a cutting operation. Also, the use of several different parts can be exploited to reduce the cost and/or weight of the materials. Also, the surface  4128  (shown in  FIG. 78 ) can be formed prior to the assembly operation to provide a consistent finish (in terms of shape). 
       FIG. 80  illustrates an isometric view of an embodiment of a spacer element  4216 , showing the spacer element  4216  formed by coupling two structures together along their respective longitudinal axes, in accordance with some described embodiments. The longitudinal axis is defined along the x-axis in the Cartesian coordinate system. The spacer element  4216  may include a first part  4282   a  coupled with a second part  4282   b . As shown, the first part  4282   a  may include a recess  4240  such that when the first part  4282   a  is coupled with the second part  4282   b , the recess  4240  forms a through hole that can accommodate a strap (not shown in  FIG. 80 ). By forming a spacer element  4216  using the first part  4282   a  and the second part  4282   b , the spacer element  4216  can be made by two different materials, such as a metal and a non-metal. Also, by forming the recess  4240  prior to assembling the first part  4282   a  with the second part  4282   b , the recess  4240  can be made through different cutting means. 
       FIG. 81  illustrates an isometric view of an embodiment of a spacer element  4316 , showing the spacer element  4316  formed by coupling two structures together along different axes, in accordance with some described embodiments. The longitudinal axis is defined along multiple z-axes in the Cartesian coordinate system. The spacer element  4316  may include a first part  4382   a  coupled with a second part  4382   b . As shown, the first part  4382   a  and the second part  4382   b  may each be pre-fabricated such that when the first part  4382   a  is assembled with the second part  4382   b , a recess  4340  forms. The recess  4340  may define a through hole that can accommodate a strap (not shown in  FIG. 81 ). By forming a spacer element  4316  using the first part  4382   a  and the second part  4382   b , the spacer element  4316  can be made by two different materials, such as a metal and a non-metal. Also, by forming the recess  4340  prior to assembling the first part  4382   a  with the second part  4382   b , the recess  4340  can be made through different cutting means. 
       FIG. 82  illustrates an isometric view of an embodiment of a spacer element  4416 , showing an insert  4472  designed for integration with the spacer element  4416 , in accordance with some described embodiments. As shown, the spacer element  4416  includes a through hole  4474  having a size and shape in accordance with the insert  4472 . The insert  4472  may include a pre-molded or pre-fabricated part. The insert  4472  may include a metal or a hardened plastic material, as non-limiting examples. Further, the insert  4472  includes a through hole  4440  designed to receive a strap (not shown in  FIG. 82 ). The through hole  4440  may include a convex and a flat surface, similar to prior embodiments (of a roller element or a spacer element). In this manner, the cutting operation used to form the through hole  4474  may be less complex, as compared to prior embodiments, as the through hole  4440  is formed to a specification prior to inserting the insert  4472  into the through hole  4474  of the spacer element  4416 . 
     In some instances, it may be advantageous to provide a lubricating material (such as oil or grease, as non-limiting examples) to a hinge assembly. The lubricating material may provide a more consistent coefficient of friction between parts (such as roller elements and spacer elements), thereby providing more reliable and predictable use of the hinge assembly. Also, the lubricating material may reduce wear on the parts of the hinge assembly. However, when the lubricating material is applied, some consideration should be given to ensure that the lubricating material does not leave the hinge assembly and contact a user of a system that incorporates the hinge assembly.  FIGS. 83-88  show and described various methods to integrate a feature into a hinge assembly to limit or prevent user exposure to a lubricating material.  FIGS. 83-88  show several roller elements and spacer elements of a hinge assembly. The roller elements and/or the spacer elements may include a lubricant-doped material (such as Teflon, carbon fiber, or graphite, physical vapor deposition coating, diamond like carbon coating, or the like). Also, the roller elements and spacer elements shown in  FIGS. 83-88  may include materials such as plastic, metal, or a combination thereof. 
       FIG. 83  illustrates an isometric view of an embodiment of a system  4500 , showing a cover  4581  that extends over a hinge assembly  4504 , in accordance with some described embodiments. As shown, the system  4500  includes a first housing part  4502   a  and a second housing part  4502   b  connected with the first housing part  4502   a  by the hinge assembly  4504 . The system  4500  further includes a cover  4581  that extends over the hinge assembly  4504  to maintain a lubricating material  4591  (shown as a dotted line) between the cover  4581  and the hinge assembly  4504 . The lubricating material  4591  may be dispersed throughout various locations in the hinge assembly  4504 . 
     As shown, the system  4500  is in an open position. However, the system  4500  may transition from the open position to a closed position, which may cause movement of not only the hinge assembly  4504  but also the cover  4581 . In this regard, the system  4500  may include a tensioning system  4570  coupled to an end of the cover  4581 . For purposes of illustrations, some parts of the second housing part  4502   b  are removed. When then system  4500  transitions from the open position to the closed position, or vice versa, the tensioning system  4570  provides a pulling force (that may include a constant pulling force) in the directions indicated by the arrow  4571 . While applying a pulling force, the tensioning system  4570  allows part of the cover  4581  to move into the second housing part  4502   b  (when transitioning to the closed position), but stills allows part of the cover  4581  to move out of the second housing part  4502   b  (when transitioning to the open position). As a result, the cover  4581  is less susceptible to wrinkling and/or becoming pinched between spacer and roller elements (not labeled) of the hinge assembly  304 . Further, the cover  4581  may include openings, or slots, that further prevent unwanted wrinkling in the closed position. For example, the cover  4581  may include a first opening  4583   a  and a second opening  4583   b , representative of several additional openings of the cover  4581 . 
     Although not shown, the system  4500  may include a second tensioning system in the first housing part  4502   a  to provide an additional pulling force to the cover  4581 . Further, the system  4500  may include fasteners (including screws, adhesives, and/or rivets as non-limiting examples) designed to fasten one or both ends of the cover  4581  to the housing parts. When both ends of the cover  4581  are fastened, the tensioning system  4570  may be removed. 
       FIG. 84  illustrates an isometric view of an embodiment of a system  4600 , showing a cover  4681  and several rails of a hinge assembly  4604  designed to maintain the cover  4681 , in accordance with some described embodiments. As shown, the system  4600  includes a first housing part  4602   a  and a second housing part  4602   b  connected with the first housing part  4602   a  by the hinge assembly  4604 . The system  4600  further includes a cover  4681  that extends over the hinge assembly  4604  to maintain a lubricating material  4691  (shown as a dotted line) between the cover  4681  and the hinge assembly  4604 . The lubricating material  4691  may be dispersed throughout various locations in the hinge assembly  4604 . 
     As shown, the system  4600  is in an open position. However, the system  4600  may transition from the open position to a closed position, which may cause movement of not only the hinge assembly  4604  but also the cover  4681 . In this regard, the hinge assembly  4604  may include rails, including a first rail  4605   a  and a second rail  4605   b  (both representative of additional rails) that define an underpass through which the cover  4681  extends. As a result, when the system  4600  undergoes a transition to the closed position, the rails may engage the cover  4681  to limit or prevent further movement of the cover  4681 . 
       FIG. 85  illustrates a side view of the system  4600  shown in  FIG. 84 , showing the cover  4681  passing through the rails. As shown, the first rail  4605   a  (representative of the remaining rails) provides an underpass for the cover  4681 . As a result, the cover  4681  is maintained between the rails and the hinge assembly  4604 . Also, when the cover  4681  remains over the hinge assembly  4604 , the lubricating material  4691  remains in or on the hinge assembly  4604  to promote a consistent coefficient of friction as well as reduced wear. 
       FIG. 86  illustrates an isometric view of an alternate embodiment of a system  4700 , showing several plates that cover the hinge assembly  4704 , in accordance with some described embodiments. As shown, the system  4700  includes a first housing part  4702   a  and a second housing part  4702   b  connected with the first housing part  4702   a  by the hinge assembly  4704 . The hinge assembly  4704  may include several plates, including a first plate  4707   a  and a second plate  4707   b  (both representative of additional plates) that define cover to limit or prevent a lubricating material  4791  from exiting the hinge assembly  4704 . The lubricating material  4791  may be dispersed throughout various locations in the hinge assembly  4704 . As shown, the plates are modular. In other words, the plates are disconnected from each other. 
       FIG. 87  illustrates a side view of the system  4700  shown in  FIG. 86 , showing the plates covering the hinge assembly. As shown, the first plate  4707   a  and the second plate  4707   b  (both representative of the remaining rails) are coupled to a first spacer element  4716   a  and a second spacer element  4716   b , respectively, of the hinge assembly  4704 . Also, the first plate  4707   a  may pass over a roller element  4714  of the hinge assembly  4704 , and may also at least partially pass over the second spacer element  4716   b . The remaining plates may include a similar configuration. In this manner, the plates can collectively act as a cover for the lubricating material  4791 , while modular design provides flexibility for the hinge assembly  4704 . 
       FIG. 88  illustrates a side view of a hinge assembly  4804 , showing a cover  4881  that wraps around a roller element  4814  and passes through consecutive spacer elements, in accordance with some described embodiments. As shown, the hinge assembly  4804  may include a first spacer element  4816   a  and a second spacer element  4816   b . The first spacer element  4816   a  and the second spacer element  4816   b  include a first opening  4821   a  and a second opening  4821   b , respectively. The cover  4881  may pass through the first opening  4821   a  and the second opening  4821   b  and form a closed loop around the roller element  4814 . In this manner, the cover  4881  can confine a lubricating material  4891  within the cover  4881 . Also, as the first spacer element  4816   a  and the second spacer element  4816   b  rotate clockwise and counter-clockwise (as indicated by the arrows with dotted lines) relative to the roller element  4814 , the cover  4881  is free to pass through the first opening  4821   a  and/or the second opening  4821   b . These paths (through the spacer elements) may prevent bunching, wrinkling, and/or stretching of the cover  4881 , thereby allowing the hinge assembly  4804  to operate in a desired manner. 
       FIG. 89-101  show and described various systems and electronic devices. The systems and electronic devices shown in  FIG. 89-101  may include several features previously described for a system. 
       FIG. 89  illustrates an alternate embodiment of a system  4900  having a hinge assembly  4904  coupled to a housing part  4902   a  and a stand  4902   b , in accordance with some described embodiments. The system  4900  may include a desktop computing device. The hinge assembly  4904  is designed to allow the housing part  4902   a  to rotate or pivot relative to the stand  4902   b . The housing part  4902   a  may include a display (not shown in  FIG. 89 ), including a display with a touch input layer designed to receive a command via a touch input. The hinge assembly  4904  may include any features and/or materials previously described for a hinge assembly. Accordingly, the hinge assembly  4904  may include roller elements (such as a first roller element  4914   a  and a second roller element  4914   b ), spacer elements (such as a first spacer element  4916   a  and a second spacer element  4916   b ), and a strap  4920  extending through the hinge assembly  4904  and pulled in tension via a tensioning element (not shown in  FIG. 89 ). The strap  4920  may also include ends positioned in the housing part  4902   a  and the stand  4902   b.    
     While the prior embodiments include a hinge assembly that includes multiple roller elements, some embodiments of a hinge assembly include a single roller element. For example,  FIG. 90  illustrates an alternate embodiment of a system  5000  having a hinge assembly  5004  coupled to a first housing part  5002   a  and a second housing part  5002   b , with the hinge assembly  5004  having a roller element  5014 , in accordance with some described embodiments. The hinge assembly  5004  is designed to allow the first housing part  5002   a  to rotate or pivot relative to the second housing part  5002   b , or vice versa. The first housing part  5002   a  and the second housing part  5002   b  may include any designs or features previously described for a first housing part and a second housing part, respectively. As shown, the hinge assembly  5004  may include a roller element  5014  that defines a single roller element for the hinge assembly  5004 . Also, the hinge assembly  5004  may further include a first spacer element  5016   a  and a second spacer element  5016   b . As shown, the first spacer element  5016   a  and the second spacer element  5016   b  include a concave surface to receive the roller element  5014  and to pair with the first housing part  5002   a  and the second housing part  5002   b , respectively. As a result, the roller element  5014  may rotate and slide along the first spacer element  5016   a  and/or the second spacer element  5016   b . Alternatively, the first spacer element  5016   a  may slide along the roller element  5014 . The hinge assembly  5004  may further include a strap  5020  extending through the hinge assembly  5004  and pulled in tension via a tensioning element (not shown in  FIG. 90 ), thereby providing frictional forces between the roller element  5014  and the aforementioned spacer elements. The strap  5020  may also include an end positioned in the first housing part  5002   a  and an opposing end position in the second housing part  5002   b . With the hinge assembly  5004  reducing the number of roller elements and spacer elements, the system  5000  can include a reduced bend radius, as compared to some prior embodiments. In this regard, the system  5000 , in the closed position, can place the first housing part  5002   a  closer to the second housing part  5002   b , thereby providing a more compact system. Further, the strap  5020  may include non-stretchable material(s) that allow for the improved (reduced) bend radius, as the stiff materials for prior straps is not needed due in part to the need for synchronous motion of elements being removed for the system  5000 . 
       FIG. 91  illustrates an alternate embodiment of a system  5100  having a hinge assembly  5104  coupled to a housing part  5102   a  and a stand  5102   b , in accordance with some described embodiments. The housing part  5102   a  may include a display (not shown in  FIG. 70 ), including a display with a touch input layer designed to receive a command via a touch input. Rather than having multiple, separable parts for a hinge assembly, the hinge assembly  5104  may be integrally formed with the housing part  5102   a  and the stand  5102   b . As shown in the enlarged view, the hinge assembly  5104  may be defined by a rounded portion  5186  of the stand  5102   b  as well as a concave portion  5188  of the housing part  5102   a  that receives the rounded portion  5186 . The hinge assembly  5104  may further include a strap  5120  extending through the hinge assembly  5104  and pulled in tension via a tensioning element (not shown in  FIG. 70 ), thereby providing frictional forces between the housing part  5102   a  and the stand  5102   b . The strap  5120  may also include ends positioned in the housing part  5102   a  and the stand  5102   b . The strap  5120  may also counterbalance a force provided by the weight of the housing part  5102   a . As shown in the enlarged view, the rounded portion  5186  provides a sliding path (denoted by the two-sided arrow  5190 ) that provides a relatively large rotational path for the housing part  5102   a  to move about the stand  5102   b . As a result, the system  5100  may require less tension, which may include lower cost materials for the strap  5120 . 
       FIG. 92  illustrates an isometric view of an embodiment of a system  5200  having multiple hinge assemblies, in accordance with some described embodiments. The system  5200  may include an accessory device, such as a cover or folio, suitable for use with an electronic device, such as a mobile communication device, a laptop computing device, or a tablet computing device. As shown, the system  5200  may include a first housing part  5202   a , a second housing part  5202   b , and a third housing part  5202   c . The system  5200  may further include a first hinge assembly  5204   a  that couples together the first housing part  5202   a  and the second housing part  5202   b , allowing the first housing part  5202   a  to rotate or pivot with respect to the second housing part  5202   b , or vice versa. The system  5200  may further include a second hinge assembly  5204   b  that couples together the second housing part  5202   b  and the third housing part  5202   c , allowing the second housing part  5202   b  to rotate or pivot with respect to the third housing part  5202   c , or vice versa. 
     The first hinge assembly  5204   a  may include multiple roller elements (including a first roller element  5214   a  and a second roller element  5214   b ) and multiple spacer elements (including a spacer element  5216   a ). The first hinge assembly  5204   a  may include additional roller elements and spacer elements. The second hinge assembly  5204   b  may include multiple roller elements (including a first roller element  5214   c  and a second roller element  5214   d ) and multiple spacer elements (including a spacer element  5216   b ). The second hinge assembly  5204   b  may include additional roller elements and spacer elements. 
     The system  5200  may include multiple straps, such as a first strap  5220   a , a second strap  5220   b , and a third strap  5220   c . The first strap  5220   a , the second strap  5220   b , and the third strap  5220   c  may include any material(s) and/or provide any feature(s) previously described for a strap. Also, while a discrete number of straps are shown, the number of straps may vary. In some embodiments (not shown), the system  5200  includes a first set of one or more straps that extends through the first hinge assembly  5204   a  but does not extend through the second hinge assembly  5204   b , and may further include a second set of one or more straps that extends through the second hinge assembly  5204   b  but does not extend through the first hinge assembly  5204   a . In the embodiment shown in  FIG. 92 , the first strap  5220   a , the second strap  5220   b , and the third strap  5220   c  extend through both the first hinge assembly  5204   a  and the second hinge assembly  5204   b . Also, although not shown, each of the first strap  5220   a , the second strap  5220   b , and the third strap  5220   c  may include a tensioning element, including an adjustable tensioning element, designed to provide an adjustable pulling force to their respective strap. Accordingly, the frictional forces between roller elements and spacer elements of the first hinge assembly  5204   a  and the second hinge assembly  5204   b  can be adjusted. Due to the aforementioned straps extending through the first hinge assembly  5204   a  and second hinge assembly  5204   b , the first hinge assembly  5204   a  and second hinge assembly  5204   b  may “communicate” and work in conjunction with each other. This will be shown and discussed below. Also, in order to couple the system  5200  to a device (not shown in  FIG. 92 ), the system  5200  may include a magnetic element  5290  that magnetically couples to, and retains, the device with the system  5200 . Alternatively, or in conjunction, the magnetic element  5290  can include mechanical features (extensions and/or recesses) designed to hold and carry the device. 
       FIG. 93  illustrates a side view of the system  5200  shown in  FIG. 92 , showing the system  5200  in a closed position. As shown, the first housing part  5202   a  and the second housing part  5202   b  may cover, or at least substantially cover, the third housing part  5202   c  in the closed position. Also, the first hinge assembly  5204   a  allows the first housing part  5202   a  to extend flat, or 180 degrees, with respect to the second housing part  5202   b , while the second hinge assembly  5204   b  allows the second housing part  5202   b  to rotate or pivot with respect to the third housing part  5202   c.    
       FIG. 94  illustrates a side view of the system  5200  shown in  FIGS. 92 and 93 , showing the system  5200  in an open position. In some instances, the system  5200  is designed to function in accordance with a two-step process. For example, in Step  1 , the second hinge assembly  5204   b  allows the first housing part  5202   a  and the second housing part  5202   b  to rotate or pivot away from the third housing part  5202   c . Moreover, the first hinge assembly  5204   a  may be “locked” or prevented from allowing relative movement between the first housing part  5202   a  and the second housing part  5202   b . The first hinge assembly  5204   a  may remain locked when the second housing part  5202   b  is less than a particular angle with respect to the third housing part  5202   c , which may include a predetermined angle set by the manufacturer of the system  5200 . This will be further discussed below. In some instances, the first strap  5220   a , or a combination of the first strap  5220   a , the second strap  5220   b , and the third strap  5220   c  (the latter straps shown in  FIG. 92 ), along with a tensioning element(s) (not shown in  FIG. 94 ), may provide sufficient frictional forces between the roller elements and the spacer elements to lock the first hinge assembly  5204   a . Alternatively, the system  5200  may include an accelerometer or a gyroscopic sensor (not shown in  FIG. 94 ) that determines a relative position/angle of the second housing part  5202   b  with respect to the third housing part  5202   c  so that a processor circuit (not shown in  FIG. 94 ) of the system  5200  can monitor and assist in maintaining the first hinge assembly  5204   a  in a locked position. 
     However, when the second housing part  5202   b  (or the combination of the first housing part  5202   a  and the second housing part  5202   b ) is positioned away from the third housing part  5202   c  at a particular angle, the hinge assemblies may change their locking/unlocking configurations. For example,  FIG. 95  illustrates a side view of the system  5200  shown in  FIG. 94 , further showing the second housing part  5202   b  positioned at a predetermined angle  5292  with respect to the third housing part  5202   c . The predetermined angle  5292  in  FIG. 95  is approximately 45 degrees. However, the predetermined angle  5292  may be approximately in the range of 30 to 80 degrees. As shown in Step  2 , when the second housing part  5202   b  is positioned at the predetermined angle  5292  with respect to the third housing part  5202   c , the first hinge assembly  5204   a  may “unlock” and allow relative movement of the first housing part  5202   a  with respect to the second housing part  5202   b . The system  5200  may determine when the second housing part  5202   b  reaches the predetermined angle  5292 . For example, when the first strap  5220   a  (or a combination of the first strap  5220   a , the second strap  5220   b , and the third strap  5220   c ) provides a predetermined tension, the first hinge assembly  5204   a  may transition from the locked to the unlocked position. Alternatively, the accelerometer or gyroscopic sensor (described above) may determine when the second housing part  5202   b  is at the predetermined angle  5292 . 
     Furthermore, when the second housing part  5202   b  is at the predetermined angle  5292  and the first hinge assembly  5204   a  allows the first housing part  5202   a  to rotate or pivot, the second hinge assembly  5204   b  may transition from an unlocked position to a locked position, thereby preventing the second housing part  5202   b  from movement relative to the third housing part  5202   c . Accordingly, the system  5200  may provide a dual hinge assembly with mutually exclusive movement in that in one configuration the first hinge assembly  5204   a  is unlocked the second hinge assembly  5204   b  is locked, and in another configuration the first hinge assembly  5204   a  is locked the second hinge assembly  5204   b  is unlocked. This allows a user to position the system  5200  in a functional and a useful manner, particularly when the system  5200  carries an electronic device (not shown in  FIG. 95 ). 
       FIG. 96  illustrates an isometric view of an embodiment of an electronic device  5301 , in accordance with some described embodiments. In some embodiments, the electronic device  5301  includes a laptop computing device. The various embodiments of system described herein may include several features described for the electronic device  5301 . As shown, the electronic device  5301  may include a display housing  5303  and a base portion  5305  hingedly coupled to the display housing  5303 . In this regard, the display housing  5303  can rotate with respect to the base portion  5305 , and vice versa. The display housing  5303  may be coupled to the base portion  5305  by at least one of the hinge assemblies described herein. 
     The display housing  5303  may include a display  5307  designed to present visual information to a user, in the form of textual information, still images, and/or video. In order to control the display  5307 , the base portion  5305  may include several control features, such as a keyboard assembly  5309 , a touch pad  5311 , and/or a display function bar  5313 , with the latter providing a dynamic set of touch inputs that changes in accordance what is presented on the display  5307 . The features described herein for the display housing  5303  and base portion  5305  may be present on a first housing part and a second housing, respectively, described herein. 
       FIG. 97  illustrates an isometric view of an embodiment of an electronic device  5401 , in accordance with some described embodiments. The electronic device  5401  may include a laptop computing device. As shown, the electronic device  5401  may include a first housing  5402   a , or display housing, that carries a display  5407  of the electronic device  5401 . The electronic device  5401  may further include a second housing  5402   b , or base portion, that includes a keyboard assembly  5409  and a touch pad  5411 , both of which are designed to generate an input or command to a processing system (not shown in  FIG. 98 ) of the electronic device  5401 . The electronic device  5401  may further include a hinge assembly  5404  coupled to the first housing  5402   a  and the second housing  5402   b . The hinge assembly  5404  allows for rotational movement of the first housing  5402   a  with respect to the second housing  5402   b , and vice versa. The electronic device  5401  is shown in an open position. However, the hinge assembly  5404  allows the first housing  5402   a  to rotate over the second housing  5402   b  such that the display  5407  is positioned over the keyboard assembly  5409  and the touch pad  5411 , thereby defining a closed positioned. The hinge assembly  5404  may include one or more features described herein for hinge assemblies, spacer elements, roller elements, and/or straps, as non-limiting examples. Also, the aforementioned systems described in this detailed description may include any feature or features described herein for the electronic device  5401 . 
       FIG. 98  illustrates a side view of the electronic device  5401  shown in  FIG. 97 , showing the electronic device in a closed position. As shown, the first housing  5402   a  includes a thickness  5421  and the second housing  5402   b  includes a thickness  5423  that is greater than the thickness  5421  of the first housing  5402   a . Also, the thickness  5421  of the first housing  5402   a  is the same, or at least approximately the same, thickness of the hinge assembly  5404 . Also, the second housing  5402   b  may include a notch  5415 , or curved portion, that allows a user to position a digit (such as a finger) under the first housing  5402   a  and pull the first housing  5402   a  away from the second housing  5402   b , and transition the electronic device  5401  from the closed position to the open position (as shown in  FIG. 98 ). 
     The second housing  5402   b  may include a recess. As shown in  FIG. 98 , the recess may position the keyboard assembly  5409  and the touch pad  5411  sub-flush, or below, an uppermost surface of the second housing  5402   b . In this manner, in the closed positioned, the display  5407  may not contact the keyboard assembly  5409  or the touch pad  5411 . Also, in the closed position, the electronic device  5401  defines an opening  5417  capable of carrying an object (not shown in  FIG. 99 ) such as a stylus or other interactive tool designed to interact with the display  5407 . In this manner, when the display  5407  includes touch input capabilities, the electronic device  5401  can carry the object and the object can be removed from the opening  5417  and the user can interact with the display with the object. As shown, the hinge assembly  5404  and the second housing  5402   b  are shaped such that the opening  5417  includes a circular opening. However, other shapes are possible. 
       FIGS. 99-101  illustrate additional embodiments of electronic devices. The hinge assemblies shown in  FIGS. 99-101  may include any feature described herein for hinge assemblies, spacer elements, roller elements, and/or straps, as non-limiting examples. 
       FIG. 99  illustrates a side view of an alternative embodiment of an electronic device  5501 , showing the electronic device  5501  in a closed position. As shown, the electronic device  5501  may include a first housing  5502   a , a second housing  5502   b , and a hinge assembly  5504  coupled with the first housing  5502   a  and the second housing  5502   b . The first housing  5502   a  includes a thickness  5521  and the second housing  5502   b  includes a thickness  5523  that is the same, or at least approximately the same, as the thickness  5521  of the first housing  5502   a . Also, the thickness  5521  of the first housing  5502   a  is the same, or at least approximately the same, thickness of the hinge assembly  5504 . In this manner, the electronic device  5501  may form a “wedge” shape in the closed position, as shown in  FIG. 99 . 
       FIG. 100  illustrates an isometric view of an alternative embodiment of an electronic device  5601 , showing components of the hinge assembly  5604  having chamfered regions, in accordance with some described embodiments. The electronic device  5601  may include any features described herein for an electronic device. As shown, the electronic device  5601  may include a first housing  5602   a , a second housing  5602   b , and a hinge assembly  5604  coupled with the first housing  5602   a  and the second housing  5602   b.    
     The hinge assembly  5604  can be modified such that the appearance of the hinge assembly  5604  matches that of the first housing  5602   a  and the second housing  5602   b . For example, the hinge assembly  5604  may include a first roller element  5614   a  and a spacer element  5616  having a chamfered region  5690   a  and a chamfered region  5690   b , respectively. The chamfered region  5690   a  of the first roller element  5614   a  and the chamfered region  5690   b  of the spacer element  5616  provide a reduced thickness at an outer perimeter of the hinge assembly  5604  such that the thickness of the hinge assembly  5604  includes a thickness, or at least an approximate thickness, as that of the first housing  5602   a  at the outer perimeter. Further, the hinge assembly  5604  may include a second roller element  5614   b  that includes a chamfered region  5690   c  that provides a reduced thickness at an outer perimeter of the hinge assembly  5604  such that the thickness of the hinge assembly  5604  includes a thickness, or at least an approximate thickness, as that of the second housing  5602   b  at the outer perimeter. Although not labeled, the remaining roller elements and spacer elements may include chamfered regions similar to those described for  FIG. 101 . Due in part to each roller element and each spacer element having a chamfered region, the hinge assembly  5604  includes a consistent appearance of a reduced thickness and provides an edge aligned with the first housing  5602   a  and the second housing  5602   b.    
       FIG. 101  illustrates a side view of the electronic device shown in  FIG. 100 , showing the electronic device  5601  in a closed position. Due in part to the chamfered regions of the roller elements and the spacer elements of the hinge assembly  5604 , the hinge assembly  5604  may include an appearance of the same or similar thickness as that of the first housing  5602   a  and the second housing  5602   b . This may enhance the overall aesthetic appearance of the electronic device  5601 , as the chamfered regions follow the curvature of the hinge assembly  5604  and provide an edge aligned with the first housing  5602   a  and the second housing  5602   b  to provide a consistent finish. 
       FIG. 102  illustrates an isometric view of an alternate embodiment of an electronic device  5701 , showing a hinge assembly  5704  that includes a roller element  5714  integrated with a display housing  5703  and a spacer element  5716  integrated with a base portion  5705 , in accordance with some described embodiments. As shown, the display housing  5703  is coupled to the base portion  5705  by the hinge assembly  5704 . Similar to prior embodiments, the display housing  5703  includes a display  5707 , and the base portion  5705  includes a keyboard assembly  5709  and a touch pad  5711 . 
     The roller element  5714  and the display housing  5703  may be formed during an assembly operation such that the roller element  5714  and the display housing  5703  are formed from a single, continuous block of material (or materials). Similarly, the spacer element  5716  and the base portion  5705  may be formed during an assembly operation such that the spacer element  5716  and the base portion  5705  are formed from a single, continuous block of material (or materials). The assembly operation may include machining, cutting, or molding, as non-limiting examples. Also, as shown in  FIG. 102 , the electronic device  5701  is in the open position. However, the electronic device  5701  can transition from the open position to the closed position when the roller element  5714  rotates along the spacer element  5716 . In some embodiment (not shown in  FIG. 102 ), the Also, the roller element  5714  is integrated with the base portion  5705  and the spacer element  5716  is integrated with the display housing  5703 . Also, although not shown, the hinge assembly  5704  may include one or more straps, each of which may be coupled to a tensioning element. 
     The hinge assembly  5704  may include one or more cylindrical parts positioned into openings of the roller element  5714 . These cylindrical parts may aligned with the roller element  5714 , and may be fixed in place subsequent to alignment. For example, the hinge assembly  5704  includes a first cylindrical part  5715   a  and a second cylindrical part  5715   b  that are positioned in openings of the roller element  5714 . During rotation of the display housing  5703  relative to the base portion  5705  (or vice versa), the roller element  5714  rotates along the spacer element  5716 , while the first cylindrical part  5715   a  and the second cylindrical part  5715   b  remain fixed. 
     The first cylindrical part  5715   a  and the second cylindrical part  5715   b  can be designed to retain the display housing  5703 . For example, as shown in the enlarged view, the first cylindrical part  5715   a  may include a first protruding feature  5717   a  and a second protruding feature  5717   b . For purposes of simplicity and illustration, the keys of the keyboard assembly  5709  are removed in the enlarged view. The first protruding feature  5717   a  and the second protruding feature  5717   b  may fit into a first recess and a second recess (not labeled), respectively, of the roller element  5714 . This will be further described below. Also, the hinge assembly  5704  may include tensioning elements coupled to the aforementioned cylindrical parts. For example, the hinge assembly  5704  includes a tensioning element  5770  coupled to the first cylindrical part  5715   a . The tensioning element  5770  may include an adjustable tensioning element. It should be noted that the second cylindrical part  5715   b  may include any features, including a tensioning element, shown and described for the first cylindrical part  5715   a . Also, while a first cylindrical part  5715   a  and a second cylindrical part  5715   b  are shown, a different number of cylindrical parts may be used, such as a single, centrally located cylindrical part, or three or more cylindrical parts (as non-limiting examples). 
       FIG. 103  illustrates an exploded view of the hinge assembly  5704  of the electronic device  5701  shown in  FIG. 102 . As shown, the roller element  5714  may include a first recess  5721   a  and a second recess  5721   b  designed to receive the first protruding feature  5717   a  and the second protruding feature  5717   b , respectively, of the first cylindrical part  5715   a . The first recess  5721   a  and the second recess  5721   b  extend to the outer perimeter of the roller element  5714 . Subsequent to positioning the protruding features into the recesses, the recesses can be filled with a filler material (not shown in  FIG. 103 ) in order to retain the protruding features, and accordingly, the first cylindrical part  5715   a , in alignment with the roller element  5714 . The filler material may include a material similar to the material that forms the display housing  5703  and the roller element  5714 . However, subsequent to applying the filler material, the roller element  5714  is still capable of rotational movement relative to the first cylindrical part  5715   a . Alternatively, the first protruding feature  5717   a  and the second protruding feature  5717   b  may include spring-loaded protruding features designed to retract into the body of the first cylindrical part  5715   a  during installation into the roller element  5714 , and subsequently extend into the recesses of the roller element  5714 . In this manner, the first recess  5721   a  and the second recess  5721   b  may be include a size and shape (such as a cylindrical recess) corresponding to the first protruding feature  5717   a  and the second protruding feature  5717   b , and a filler material may not be required. 
     The tensioning element  5770  may include a spring  5771  designed to bend or flex, and provide a pulling force, or tension, to the first cylindrical part  5715   a . The tensioning element  5770  may further include a fastener  5773  designed to enter an opening  5723  of the first cylindrical part  5715   a . The engagement between the fastener  5773  and the opening  5723  may include a threaded engagement. The fastener  5773  can be adjusted (e.g., rotationally driven) to adjust the flexing of the spring  5771 , thereby adjusting the tension provided by the tensioning element  5770 . Again, it should be noted that the second cylindrical part  5715   b  (shown in  FIG. 102 ) may include any features, including a tensioning element, shown and described for the first cylindrical part  5715   a.    
       FIG. 104  illustrates a side view of the electronic device  5701  shown in  FIG. 102 . As shown, the electronic device  5701  is in the open position and the display housing  5703  is rotated away from the base portion  5705 . However, the roller element  5714  can rotate along the spacer element  5716 , causing the display housing  5703  to rotate toward the base portion  5705  and transition to the closed position, as indicated by the dotted lines. 
       FIG. 105  illustrates a block diagram of a portable electronic device  5800 , in accordance with some embodiments. The portable electronic device  5800  is capable of implementing the various techniques described herein. The portable electronic device  5800  may include any features described herein for an electronic device. Also, electronic devices described herein may include any feature or features described for the portable electronic device  5800 . In some embodiments, the portable electronic device  5800  takes the form of the system  100  (shown in  FIG. 1 ). The portable electronic device  5800  can include one or more processors  5810  for executing functions of the portable electronic device  5800 . The one or more processors  5810  can refer to at least one of a central processing unit (CPU) and at least one microcontroller for performing dedicated functions. 
     According to some embodiments, the portable electronic device  5800  can include a display unit  5820 . The display unit  5820  is capable of presenting a user interface that includes icons (representing software applications), textual images, and/or motion images. In some examples, each icon can be associated with a respective function (such as a software application) that can be executed by the one or more processors  5810 . In some cases, the display unit  5820  includes a display layer (not illustrated), which can include a liquid-crystal display (LCD), light-emitting diode display (LED), organic light-emitting diode display (OLED), or the like. According to some embodiments, the display unit  5820  includes a touch input detection component and/or a force detection assembly that can be configured to detect changes in an electrical parameter (e.g., electrical capacitance value) when the user&#39;s appendage (acting as a capacitor) comes into proximity with the display unit  5820  (or in contact with a transparent layer that covers the display unit  5820 ). The display unit  5820  is connected to the one or more processors  5810  via one or more connection cables  5822 . 
     According to some embodiments, the portable electronic device  5800  can include one or more input/output components  5840  (also referred to as “I/O components”) that enable communication between a user and the portable electronic device  5800 . In some cases, the one or more input/output components  5840  can refer to a button or a switch that is capable of actuation by the user. In some cases, the one or more input/output components  5840  can refer to a soft key that is flexibly programmable to invoke any number of functions. In some examples, the one or more input/output components  5840  can refer to a switch having a mechanical actuator (e.g., spring-based switch, slide-switch, rocker switch, rotating dial, etc.) or other moving parts that enable the switch to be actuated by the user. In some examples, the one or more input/output components  5840  can include a capacitive switch that is integrated with the display unit  5820 . Also, the one or more input/output components  5840  can include a force detect assembly that includes several force detection units, each of which is designed to detection an amount of applied force (by, for example, a touch input) to the display unit  5820 . The one or more input/output components  5840  can include accelerometer that determine whether the portable electronic device  5800 , and to what extent, is accelerating or decelerating. When the one or more input/output components  5840  are used, the input/output components  5840  can generate an electrical signal that is provided to the one or more processors  5810  via one or more connection cables  5842 . 
     According to some embodiments, the portable electronic device  5800  can include a power supply  5850  that is capable of providing energy to the operational components of the portable electronic device  5800 . In some examples, the power supply  5850  can refer to a rechargeable battery. The power supply  5850  can be connected to the one or more processors  5810  via one or more connection cables  5852 . The power supply  5850  can be directly connected to other devices of the portable electronic device  5800 , such as the one or more input/output components  5840 . In some examples, the portable electronic device  5800  can receive power from another power sources (e.g., an external charging device). 
     According to some embodiments, the portable electronic device  5800  can include memory  5860 , which can include a single disk or multiple disks (e.g., hard drives), and includes a storage management module that manages one or more partitions within the memory  5860 . In some cases, the memory  5860  can include flash memory, semiconductor (solid state) memory or the like. The memory  5860  can also include a Random Access Memory (RAM) and a Read-Only Memory (ROM). The ROM can store programs, utilities or processes to be executed in a non-volatile manner. The RAM can provide volatile data storage, and stores instructions related to the operation of the portable electronic device  5800 . In some embodiments, the memory  5860  refers to a non-transitory computer readable medium, where an operating system (OS) is established at the memory  5860  that can be configured to execute software applications, confidence interval algorithms, and/or machine learning algorithms that are stored at the memory  5860 . The one or more processors  5810  can also be used to execute software applications, confidence interval algorithms, and/or machine learning algorithms that are stored at the memory  5860 . In some embodiments, a data bus  5862  can facilitate data transfer between the memory  5860  and the one or more processors  5810 . 
     According to some embodiments, the portable electronic device  5800  can include a wireless communications component  5870 . A network/bus interface  5872  can couple the wireless communications component  5870  to the one or more processors  5810 . The wireless communications component  5870  can communicate with other electronic devices via any number of wireless communication protocols, including at least one of a global network (e.g., the Internet), a wide area network, a local area network, a wireless personal area network (WPAN), or the like. In some examples, the wireless communications component  5870  can transmit data to the other electronic devices over IEEE 802.11 (e.g., a Wi-Fi® networking system), Bluetooth (IEEE 802.15.1), ZigBee, Wireless USB, Near-Field Communication (NFC), a cellular network system (e.g., a 3G/4G/5G network such as UMTS, LTE, etc.), or the like. 
       FIG. 106  illustrates a flowchart  5900  showing a method for assembling a hinge assembly of a portable computing device, in accordance with some described embodiments. The portable computing device may include a base portion and a display housing. The base portion may carry a keyboard, a touch pad, a processor circuit, a memory circuit, a battery, and flexible circuit that connect these components. 
     In step  5902 , a roller element that defines a cylindrical body is provided. The roller element may a through hole having a convex surface. Also, in addition to the through hole, the roller element may further include a cavity. The cavity may define a recess that extends partially into the roller element. 
     In step  5904 , a spacer element that includes a second through hole is provided. The spacer element may include a protrusion. In some instances, the roller element includes an additional cavity, and the cylindrical body includes an additional protrusion. 
     In step  5906 , the protrusion is positioned in the cavity. The protrusion may include a dovetail configuration that defines one or more tapered regions. Also, the cavity may also be tapered. 
     In step  5908 , a strap is extended through the through hole and the second through hole. The strap is designed to maintain contact between the roller element and the spacer elements. Also, an engagement of protrusion and the roller element within the cavity limits rotational movement of the display housing with respect to the base portion. Further, the strap may engage the convex surface when the display housing is positioned over the base portion 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium for controlling a manufacturing line. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20180802
Publication Date: 20210803
Grant Date: 20210803
Priority Date: 20170803
Inventors: ROBINSON, KEVIN M.
FARAHANI, HOUTAN R.
MILLER, ARI P.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/1681", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1616", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1679", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1616", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1679", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D11/082", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1637", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D11/0081", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1681", "inventive": true, "first": true, "tree": "[]"}, {"code": "E05D7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D11/082", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1681", "inventive": true, "first": true, "tree": "[]"}, {"code": "E05Y2900/606", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1616", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1637", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1679", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D11/0081", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05D7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "E05Y2999/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "E05Y2999/00", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 77063392