PATENT DOCUMENT

Publication Number: US-9072352-B2
Application Number: US-201414497199-A
Country: US
Kind Code: B2

Title: Accessory device

Abstract:
A cover is described that is magnetically attached to a tablet device. The cover includes at least as flap. In the described embodiment, the flap includes a plurality of segments where the first segment includes a first plurality of edge attach magnets arrayed along a first edge of the flap and where a second segment includes a second plurality of edge attach magnets arrayed along a second edge of the flap opposite the first edge.

Claims:
What is claimed is: 
     
       1. A cover suitable for releasable attachment to a tablet device having a housing with a full front opening, a display carried by the housing within and that substantially fills the full front opening, and a protective layer carried by the housing that overlays the display, comprising:
 a flap having a size and shape in accordance with the protective layer comprising: 
 first edge attach magnets located along a first edge of the flap; and 
 second edge attach magnets located along a second edge of the flap opposite the first edge, wherein in a folded configuration, the first and second edges are in proximity to each other without overlapping such that a magnetic circuit formed between corresponding first and second edge attach magnets maintain the flap in the folded configuration. 
 
     
     
       2. The cover as recited in  claim 1 , further comprising a flexible hinge assembly comprising a flexible hinge portion, the hinge portion being a continuation of the flap beyond the second edge, and a magnetic attachment unit comprising a plurality of attachment magnets that provide a magnetic field used to form a magnetic circuit through the housing. 
     
     
       3. The cover as recited in  claim 2 , wherein the magnetic circuit through the housing magnetically attaches the magnetic attachment unit with the tablet device at the housing. 
     
     
       4. The cover as recited in  claim 3 , wherein in the folded configuration, the magnetic field from the magnetic attachment unit forms a magnetic circuit that provides a repulsive magnetic force that enhances ability of the magnetic circuit maintaining the flap in the folded configuration. 
     
     
       5. The cover as recited in  claim 1 , further comprising:
 magnetic field shaping magnets that together form an aggregate magnetic field that interact with magnetic fields of the first edge attach magnets forming a resultant magnetic field having a pre-defined magnetic field strength at a corresponding pre-defined flap location. 
 
     
     
       6. The cover as recited in  claim 5 , further comprising:
 wherein the pre-defined magnetic field strength corresponds to a null magnetic field. 
 
     
     
       7. The cover as recited in  claim 6 , wherein the pre-defined flap location corresponds to a location of a magnetically sensitive circuit carried by the tablet device when the flap is configured in a closed configuration with respect to the tablet device. 
     
     
       8. The cover as recited in  claim 7 , wherein the magnetically sensitive circuit is a magnetometer. 
     
     
       9. The cover as recited in  claim 8 , wherein the magnetometer acts as a magnetic compass. 
     
     
       10. The cover as recited in  claim 1 , wherein the first edge attach magnets comprises at least one magnetic element comprising a first portion having a size commensurate with the other first edge attach magnets and a second portion. 
     
     
       11. The cover as recited in  claim 10 , wherein the first portion forms a corresponding magnetic sub-circuit with a corresponding one of the second edge attach magnets. 
     
     
       12. The cover as recited in  claim 11 , wherein the second portion forms a magnetic circuit with a corresponding magnetic element carried by the tablet device in a closed configuration that assists in limiting a lateral movement of the flap with respect to the tablet device. 
     
     
       13. The cover as recited in  claim 11 , further comprising:
 a first sensor magnet located at a first position and detectable through the protective layer by a first sensor when in proximity to the first sensor magnet; and 
 a second sensor magnet detectable through the top protective layer by a second sensor different from the first sensor when in proximity to the second sensor magnet. 
 
     
     
       14. The cover as recited in  claim 13 , wherein the first sensor magnetic comprises a first size corresponding to a distance of the first sensor magnet from a point of rotation of the flap and an angle of rotation of the flap with respect to the tablet device in a closed configuration. 
     
     
       15. The cover as recited in  claim 13 , wherein the second sensor magnetic comprises a second size corresponding to a distance of the second sensor magnet from the point of rotation and the angle of rotation of the flap with respect to the tablet device in the closed configuration. 
     
     
       16. The cover as recited in  claim 15 , wherein the first size and the second size are such that the first and second sensor magnets remain detectable by the first and second sensors, respectively, in the closed configuration when the rotation of the flap is within a pre-defined amount of rotation.

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation of U.S. application Ser. No. 13/612,230, filed Sep. 12, 2012, and entitled, “ACCESSORY DEVICE,” which claims priority under 35 U.S.C. 119(e) to U.S. Provisional Application No. 61/681,117, filed Aug. 8, 2012, and entitled, “CONSUMER ELECTRONIC PRODUCT,” the contents of which are incorporated herein by reference in their entirety for all purposes. 
    
    
     FIELD 
     The described embodiments generally relate to portable electronic devices. More particularly, the present embodiments describe various releasable attachment techniques well suited for portable electronic devices. 
     BACKGROUND 
     Recent advances in portable computing includes the introduction of hand held electronic devices and computing platforms along the lines of the iPad™ tablet manufactured by Apple Inc. of Cupertino, Calif. These handheld computing devices can be configured such that a substantial portion of the electronic device takes the form of a display assembly used for presenting visual content. The display assembly generally includes an active display area configured to present visual content and a top protective layer used to provide protection against external effects, such as would be expected during normal use. However, in some cases, additional protection can be afforded both the tablet device and display assembly using a separate accessory device that takes the form of a protective cover attached to the tablet device. However, due to the relatively large size of the display in relation to the tablet device as a whole, little space is available for attaching the protective cover to the tablet device. 
     Moreover, conventional attachment mechanisms such as mechanical fasteners, clasps, and so forth typically require an externally accessible attaching feature on the electronic device to mate with a corresponding attaching feature on the accessory device. This arrangement can detract from the overall look and feel of the handheld computing device as well as add unwanted weight and complexity as well as degrade the appearance of the hand held computing device. 
     Therefore an accessory device that provides protection to a tablet device that is at least aesthetically pleasing and easy to attach/detach is desired. 
     SUMMARY 
     This paper describes various embodiments that relate to a system, method, and apparatus for releasably attaching an accessory to an electronic device. 
     A cover is described that is magnetically attached to a tablet device. The cover includes at least a flap. In the described embodiment, the flap includes a plurality of segments where the first segment includes a first plurality of edge attach magnets arrayed along a first edge of the flap and where a second segment includes a second plurality of edge attach magnets arrayed along a second edge of the flap opposite the first edge. The flap also includes a third segment disposed between the first and second segments. When the first segment is folded back such that the first edge attach magnets are in proximity to the second edge attach magnets, a magnetic circuit is formed suitable for maintaining a triangular support structure. The cover also includes a flexible hinge assembly attached to the second side. The flexible hinge assembly includes a flexible hinge portion. In the described embodiment, the flexible hinge portion is integrated in that the flexible hinge portion is a continuation of the flap beyond the second edge. The flexible hinge assembly also includes a magnetic attachment unit comprising a plurality of attachment magnets configured to form a releasable magnetic attachment with a tablet device. 
     In another embodiment a cover configured for releasably attaching to a tablet device is described. The tablet device includes a display and associated top protective layer, a plurality of sensors, and a processor coupled to the display and the plurality of sensors. The cover includes at least a flap having a size and shape in accordance with the display. The flap, in turn, includes a first sensor magnet located at a first position in the flap and detectable through the top protective layer by a first sensor only when the first position of the flap is in proximity to the first sensor magnet, a second sensor magnet located at a second position in the flap, the second position different than the first position, the second sensor magnet being detectable through the top protective layer by a second sensor different from the first sensor of only when the second position of the flap is in proximity to the second sensor magnet. The processor uses information provided concurrently by the first and second sensors to determine a spatial relationship between the cover and the tablet device, and wherein the processor causes the tablet device to operate in a manner in accordance with the determined spatial relationship. 
     In yet another embodiment, a consumer system includes a tablet device and a cover. The tablet device includes a housing having a front opening, a display assembly disposed within the front opening that includes a display, and a top protective layer disposed adjacent to the display. The tablet device also includes a plurality of sensors configured to detect a corresponding stimulus, and a magnetic attachment unit disposed within and secured to an inside side wall of the housing. In the described embodiment the cover includes a flap formed of a first material and having a size and shape in accordance with the display, an integral hinge assembly that includes a flexible hinge, the flexible hinge formed of a continuous layer of the first material of the flap, and a hinge magnetic attachment unit configured to activate the magnetic attachment unit causing the tablet device and the cover to magnetically attach to each other. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention 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  is a simplified block diagram of an article and an electronic device that can be releasably attached to each other in a desired and repeatable manner. 
         FIG. 2A  is a simplified perspective view of an article that can be releasably attached to an electronic device via a side magnetic attachment system, in accordance with one described embodiment. 
         FIG. 2B  shows the article and the electronic device of  FIG. 2A  attached in accordance with the side magnetic attachment system. 
         FIG. 3A  is a simplified perspective view of an article that is releasably attachable to an electronic device via a top magnetic attachment system in accordance with one described embodiment. 
         FIG. 3B  shows the article and the electronic device of  FIG. 3A  magnetically attached to each to each other to form a cooperating system using the top magnetic attachment system. 
         FIG. 4A  is a simplified perspective view of an article that is releasably attachable to an electronic device via the top and side magnetic attachment systems. 
         FIG. 4B  shows a cooperating system of the attached article and the electronic device shown in  FIG. 4A  in a closed configuration. 
         FIG. 4C  shows the cooperating system of  FIG. 4B  in an open configuration. 
         FIG. 5  shows a top perspective view of an electronic device in accordance with the described embodiments. 
         FIG. 6  shows another embodiment of a magnetic attachment feature. 
         FIG. 7A  shows an electronic device in proximity to another object in the form of an accessory device having a magnetic attachment feature. 
         FIG. 7B  shows a graphical representation of a cooperating system formed by the magnetic attachment of the accessory device and the electronic device as shown in  FIG. 7A . 
         FIG. 8A  shows a first perspective view of the electronic device in the form of a tablet device and the accessory device in the form of a protective cover. 
         FIG. 8B  shows a second perspective view of the electronic device in the form of a tablet device and the accessory device in the form of a protective cover. 
         FIG. 9A  shows a closed configuration of the cooperating system formed by the tablet device and protective cover shown in  FIGS. 8A and 8B . 
         FIG. 9B  shows an open configuration of the cooperating system shown in  FIG. 9A . 
         FIG. 10A  shows a top view of an embodiment of a segmented cover assembly. 
         FIG. 10B  shows a representative magnetic assembly. 
         FIG. 11  shows representation of hinge assembly coupled to tablet device forming as part of a triangular support structure illustrating representative magnetic interaction mechanisms. 
         FIGS. 12A-12D  show representative cross sectional views of segmented cover assembly/tablet device along line AA shown in  FIG. 10A . 
         FIGS. 13A-13B  show a side view of a segmented cover configured to support a tablet device in a keyboard state. 
         FIGS. 14A-14C  show side and perspective views, respectively, of the segmented cover configured to support a tablet device in a display state. 
         FIGS. 15A-15B  shows cover assembly and tablet device in peek mode. 
         FIG. 16  shows an exploded view of segmented cover. 
         FIG. 17  is a block diagram of an arrangement of functional modules utilized by a portable media device. 
         FIG. 18  is a block diagram of an electronic device suitable for use with the described embodiments. 
     
    
    
     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. 
     The following description relates in general to a mechanism that can be used to attach together at least two suitably configured objects. In one embodiment, this can be accomplished without the use of conventional fasteners. Each of the objects can include an attachment feature arranged to provide a magnetic field having appropriate properties. When the attachment features are brought into proximity with each other, the magnetic fields can cooperatively interact based upon their respective properties, result in the objects magnetically attaching to each other in a desired and repeatable manner. For example, due at least in part to the cooperative nature of the interaction of the magnetic fields, the objects can attach to each other in a pre-determined position and relative orientation without external intervention. For example, the cooperative magnetic interaction can result in the objects self-aligning and self-centering in a desired orientation. 
     The objects can remain in the magnetically attached state if and until a releasing force of sufficient magnitude is applied that overcomes the overall net attractive magnetic force. In some cases, however, it can be desirable to detach the objects serially (along the lines of a zipper) in which case, the releasing force only need be of sufficient magnitude to overcome the net magnetic attractive force of one pair of magnetic elements at a time. Connectors such as mechanical fasteners are not required to attach the objects together. Furthermore, to prevent undue interference to the magnetic interaction between the magnetic attachment features, at least a portion of the objects in the vicinity of the magnetic attachment features can be formed of magnetically inactive materials such as plastic or non-ferrous metals such as aluminum or non-magnetic stainless steel. 
     The objects can take many forms and perform many functions. When magnetically attached to each other, the objects can communicate and interact with each other to form a cooperative system. The cooperating system can perform operations and provide functions that cannot be provided by the separate objects individually. In another embodiment, at least one device can be used as an accessory device. The accessory device can be magnetically attached to at least one electronic device. The accessory device can provide services and functions that can be used to enhance the operability of the electronic device(s). For example, the accessory device can take the form of a protective cover that can be magnetically attached to the electronic device. The protective cover can provide protection to certain aspects (such as a display) of the electronic device while enhancing the overall look and feel of the electronic device. The magnetic attachment mechanism used to magnetically attach the accessory and the electronic device can assure that the cover can only attach to the electronic device in a specific orientation. Moreover, the magnetic attachment mechanism can also assure proper alignment and positioning of the protective cover and the electronic device. 
     The protective cover can include at least a flexible hinge portion. The flexible hinge portion can include a flexible body, or tail, connected to a magnetic attachment mechanism that can include a plurality of magnets. A magnetic field provided by the magnets in the magnetic attachment mechanism can interact with a corresponding magnetic field provided by magnets in the electronic device. In this way, the hinge portion can be pivotally connected to the electronic device using only the magnets. In one embodiment, the protective cover can include a flap that is connected to the flexible hinge portion. The flap can therefore be smoothly rotated along a pivot line formed by the flexible hinge portion. When magnetically coupled to the tablet device, the smooth rotation of the flap about the pivot line can bring the flap in substantial contact with the display in a fully closed position. The flap can also be smoothly rotated about the pivot line to reveal most or all of the display. In one embodiment, the flap can be segmented by which it is meant that the flap can be divided into distinct portions that can fold and bend with respect to each other as well as the tablet device more specifically in some cases, the display. In this way, the segmented flap affords an additional option of revealing only specific portions of the display by folding individual segments to reveal a corresponding portion of the display while other segments remain in contact and therefore obscuring the display. 
     In some embodiments, the flap can include a variety of magnets that can be used to form a number of structures well suited for use with the electronic device. For example, the flap can include a first plurality of magnets linearly arrayed along a first edge (i.e., first edge magnets) and a second plurality of magnets positioned in corresponding locations along a second edge opposite the first edge (second edge magnets). In a particular embodiment, corresponding ones of the first and second edge magnets have opposite polarities. In this way, when the first edge and the second edge are brought into spatial proximity to each other, magnetic fields of the first and second edge magnets interact with each other to form a magnetic attractive force that causes the first and second edges to attach to each other. In this way, the flap can form a structure that can be used to enhance the functionality of the cover with regards to the electronic device. 
     For example, if the flap is constructed to have three independently foldable segments (referred to as segment A, segment B, and segment C) where segment A is attached to the foldable hinge at the first edge having the first edge magnets and segment C is opposite segment A that is defined in part by the second edge having the second edge magnets, a triangular structure ABC can be formed when the first edge magnets and the second edge magnets attract each other when segment A is within proximity to segment C. It should be noted that the properties of the triangular structure ABC can vary in accordance with the relative sizes of the segments A, B, and C. In other words, is segments A, B, and C are about equal in width, then triangular structure ABC can take the form of an equilateral triangle, whereas if two segments are about of equal width, then the triangular structure ABC can take on the shape of an isosceles triangle. It should be noted that in some embodiments, the triangular structure can be used to present the display at an angle of about 5-15° in a keyboard mode well suited for using a keyboard presented at the display or about 65-80° in a movie mode well suited for viewing visual content presented at the display at a comfortable viewing angle. 
     In one embodiment, the flap can include electronic circuits or other elements (passive or active) that can cooperate with electronic elements in the electronic device. As part of that cooperation, signals can be passed between the protective cover and the electronic device that can, for example, be used to modify operations of the electronic device, operations of electronic circuits or elements of the protective cover, and so forth. As an example, the electronic device can include one or more magnetically sensitive circuits such as a Hall Effect sensor and as such can detect the presence of a magnetic field. The Hall Effect sensor can respond to properties of a magnetic field (such as the presence of magnetic field, a magnetic field strength, polarity, etc.) by generating a signal. The signal can be used to alter an operating state of the electronic device. 
     Accordingly, the protective cover can include a magnetic element, or elements, such as a permanent magnet having a magnetic field that can be detected the Hall Effect sensor to generate the signal. The magnet(s) can be positioned in the protective cover in various locations in the flap that can be detected by the magnetic sensors when the magnets are proximate to the corresponding magnetic sensor. The magnetic sensors can send information to a processor in the electronic device that can evaluate the signals from the multiple sensors. The evaluation of the signals from the sensors can provide the processor with information that can be used to determine a spatial relationship between the flap and the electronic device or even if the protective cover is attached to the electronic device. For example, the processor can use the signals from the sensors to indicate a relative position of the flap to the electronic device and in response alter an operating state of the electronic device accordingly. For example, when the signals indicate that the flap is fully closed (i.e.; both magnetic sensors detect a corresponding magnetic field), then the processor can prevent the display from presenting visual content. On the other hand, if one sensor detects the corresponding magnetic field and the other sensor does not detect the corresponding magnetic field, then the processor can use this information to determine that only a portion of the display is viewable (that portion of the display corresponding to the portion of the flap having the magnet that is not detectable by the sensor). In this situation, the processor can cause the display to present visual content at only the viewable portion of the display. 
     These and other embodiments are discussed below with reference to  FIGS. 1-18 . 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. For the remainder of this discussion, a first and second object each suitably configured to magnetically attach to each other in accordance with the described embodiments will be described. It should be noted, however, that any number and type of suitably configured objects can be magnetically attached to each other in a precise and repeatable manner. In particular, for simplicity and clarity, for the remainder of this discussion, the first object is presumed to take the form of an electronic device and in particular a handheld electronic device. The handheld electronic device can, in turn, take the form of a tablet computer, portable media player, and so forth. 
       FIG. 1  is a simplified block diagram of article  10  and electronic device  12  that can be releasably attached to each other in a desired and repeatable manner. More specifically, article  10  and electronic device  12  can attach to each other at a pre-determined position and relative orientation without external intervention and without the use of mechanical fasteners. Article  10  and electronic device  12  can remain attached to each other if and until a releasing force is applied that overcomes the engagement between them. In some cases, however, it can be desirable to detach article  10  and electronic device  12  serially (along the lines of a zipper) in which case, a releasing force can be applied that can undo the engagement between article  10  and electronic device  12  about one attachment component at a time. For example, an attachment component can include a suitably matched pair of magnetic elements, one in article  10  and a second in electronic device  12 . 
     Electronic device  12  can take many forms. For example, electronic device  12  can take the form of a portable electronic device. In some examples, the portable electronic device can include housing  15 . Housing  15  can enclose and provide support for components of the portable electronic device. Housing  15  can also provide support for at least a large and prominent display occupying a substantial portion of a front face of the portable electronic device. The display can be used to present visual content. The visual content can include still images, visual, textual data, as well as graphical data that can include icons used as part of a graphical user interface, or GUI. 
     In some cases, at least a portion of the display can be touch sensitive. By touch sensitive it is meant that during a touch event, an object (such as a finger, stylus, and so on) can be placed in contact with or in proximity to an upper surface of the display. The particulars of the touch event (location, pressure, duration, and so forth) can be used to provide information to the portable electronic device for processing. In some embodiments, in addition to or in place of information being provided to the portable electronic device, information can be provided by the portable electronic device in a tactile manner using, for example, haptic actuators. It should be appreciated however that this configuration is by way of example and not by way of limitation as the electronic device can be widely varied. In one example, the portable electronic device is a tablet computer such as, for example, the iPad™ manufactured by Apple Inc. of Cupertino, Calif. 
     Article  10  can be widely varied and can take many forms such as, for example, an accessory or accoutrement of electronic device  12 . As an accessory, article  10  can be configured as a cover, a stand, a dock, a hanger, an input/output device and so on. In a particularly useful form, article  10  can take the form of a protective cover that can include a member, such as a flap, that can be positioned over the display of the portable electronic device. Like the electronic device  12 , the article  10  can also include housing  17  that can enclose and provide support for components of the article  10 . 
     Either one or both of article  10  and electronic device  12  can include attachment features. For example, article  10  can include attachment system  13  and electronic device  12  can include corresponding attachment system  14 . Attachment system  13  can cooperate with corresponding attachment system  14  to attach article  10  and electronic device  12  in a releasable manner. When attached to each other, article  10  and electronic device  12  can operate as a single operating unit. On the other hand, in the detached mode, article  10  and electronic device  12  can act separately, and if desired, as two individual parts. Attachment systems  13  and  14  can be configured in such a way that article  10  and electronic device  12  can attach to each other in a desired and repeatable manner. In other words, attachment systems  13  and  14  can repeatedly align article  10  and electronic device  12  together such that they are consistently in a pre-determined position relative to one another. 
     The attachment features can be widely varied. The attachment can be provided by various types of couplings including mechanical, electrical, static, magnetic, frictional, and/or the like. In one embodiment, the attachment cannot be seen from the outside of the article and/or electronic device. For example, the article and device can not include external visible attachment features that adversely affect the look and feel or ornamental appearance (e.g., snaps, latches, etc.), but rather attachment features that cannot be seen from the outside of the article or device and thus do not affect the look and feel or ornamental appearance of the article or device. By way of example, the attachment features can be provided by attraction surfaces that do not disturb the external surfaces of the article or device. In one embodiment, at least a portion of the attachment features utilize magnetic attraction to provide some or all of the attaching force. 
     The attachment systems can include one or more attachment features. If multiple features are used, the manner in which they secure can be the same or different. For example, in one implementation, a first attachment feature utilizes a first attachment mechanism while a second attachment feature utilizes a second attachment mechanism that is different than the first attachment mechanism. For example, the first attachment mechanism can utilize a friction coupling while the second attachment means can utilize magnetism. For example, the first and second attachment mechanisms can be provided by magnets. Although, the attachment mechanisms can be similar it should be appreciated that the configuration of the mechanisms can be different depending on the needs of the system. Further, any number and configuration of attachment mechanisms can be used. 
     In the illustrated embodiment, the attachment systems  13  and  14  each include at least a first set of corresponding attachment features  13   a / 14   a  and a second set of corresponding attachment features  13   b / 14   b . Attachment feature  13   a  can cooperate with corresponding attachment feature  14   a  to attach article  10  and electronic device in a releasable manner. In one particular implementation this is accomplished with magnetic attraction. Further, attachment feature  13   b  can cooperate with corresponding attachment feature  14   b  to further attach article  10  and electronic device in a releasable manner. In one particular implementation this is accomplished with magnetic attraction. By way of example, attachment features  13   a / 14   a  can be provided at a first location while attachment features  13   b / 14   b  can be provided at a second location. 
     In a specific example, attachment feature  14   a  can, in cooperation with attachment feature  13   a , secure electronic device  12  to article  10 . In another example, attachment feature  13   b  can secure article  10  to the electronic device  12  using attachment feature  14   b . It should be noted that the attachment systems  13  and  14  of this example can be separate or they can cooperate together to produce the attachment. If they cooperate, attachment features  14   a  and  14   b  correspond to or mate with one or more attachment features  13   a  and  13   b . In any case, the attachment features in any of these examples can be accomplished through mechanical, static, suction, magnetic attachment and/or the like. 
     The placement of the attachment systems and the attachment features within the attachment systems can be widely varied. Regarding electronic device  12 , attachment system  14  can be placed on front, back, top, bottom, and/or sides. Attachment features  14   a  and  14   b  can be placed any location within attachment system  14 . Accordingly, attachment features  14   a  and  14   b  can be placed anywhere relative to the housing and/or the display. In one example, the attachment features  14   a  and  14   b  can provide engagement along one or more of the sides of the housing (e.g., top, bottom, left, right). In another example, attachment features  14   a  and  14   b  can provide engagement at the back of electronic device  12 . In yet another example, attachment features  14   a  and  14   b  can provide engagement at the front (e.g., where, if present, a display is located) of electronic device  12 . In some cases, a combination of attachment features can be located at different regions of electronic device  12  as for example at the sides and front. In one embodiment, attachment system  14  including attachment features  14   a  and  14   b  do not disturb the surfaces of electronic device  12 . Similarly, attachment system  13  and in particular attachment features  13   a  and  13   b  do not disturb the surfaces of article  10 . 
     In accordance with one embodiment, the attachment features can include magnetic elements. The magnetic elements can be configured to help in positioning article  10  relative to electronic device  12  into a mating arrangement. The magnetic elements can further help to secure article  10  and electronic device  12  into a mating engagement. It should be noted that the engagement of article  10  and electronic device  12  can be reversed by the application of an appropriate releasing force that allows article  10  and electronic device  12  to separate back into individual objects. However, the magnetic elements can permit the article  10  and electronic device  12  to subsequently resume the mating engagement without the requirement of fasteners of any sort, mechanical or otherwise. In this way, the magnetic elements provide a repeatable and consistent engagement between article  10  and electronic device  12 . 
     Article  10  and electronic device  12  can further include components  16  and  18  respectively. Components  16  and  18  typically depend on the configuration of article  10  and electronic device  12  and can, for example, be mechanical or structural components used to provide support or they can be operational/functional components that can provide a specific set of operations/functions. The components can be dedicated to their respective devices or they may be configured for coupling with aspects of the corresponding article or device (e.g., wired or wireless). Examples of structural components can include frames, walls, fasteners, stiffeners, movement mechanisms (hinge), etc. Examples of operational components can include processors, memory, batteries, antennas, circuitry, sensors, display, inputs, and so on. Depending on their desired configuration, the components can be external (i.e., exposed at the surface) and/or internal (e.g., embedded within housing). 
       FIGS. 2A and 2B  are simplified perspective views of article  20  that can be releasably attached to electronic device  22  via a magnetic attachment system, in accordance with one described embodiment. Article  20  and electronic device  22  can generally correspond to those discussed with regards to  FIG. 1 . In one embodiment, the magnetic attachment system can be embodied as magnetic surface  24  (shown by broken lines or shading) and more particularly as magnetic surface  24  at the sides of electronic device  22 . Magnetic surface  24  can provide a magnetic field that can cooperate with a corresponding attachment feature in article  20  when placed in proximity to one another. The magnetic field can establish a net magnetic attractive force that can pull article  20  and electronic device  22  together into the mating engagement along engagement surface  26  as shown in  FIG. 2B . 
     In other words, the magnetic field provided by magnetic surface  24  can have properties such that the net magnetic attractive force between article  20  and electronic device  22  is substantially perpendicular to engagement surface  26 . Moreover, the magnetic field can result in the net magnetic attractive force between article  20  and electronic device  22  being applied uniformly along engagement surface  26 . In order to release article  20  and electronic device  22 , a releasing force can be applied to the two conjoined objects in order to overcome a net magnetic attractive force provided by the magnetic attachment system. 
     It also should be appreciated that although only one side wall is shown, in some cases different sidewalls and possibly a combination of sidewalls may be used depending on the needs of the attachment interface. It should be noted that the use of magnetic attachment precludes the need for mechanical attachments such as fasteners. Moreover, the lack of mechanical attachments and the uniformity of the overall magnetic attractive force can leave the surfaces of article  20  and electronic device  22  undisturbed helping to create an appearance of oneness by in which article  20  and electronic device  22  can appear as a single, unified entity. The uniformity in appearance can improve the overall aesthetic appeal of both article  20  and electronic device  22 . 
     In one embodiment, a magnetic surface can be created by embedding magnetically attractable elements in the form of the magnetic attachment feature within the sidewalls of electronic device  22  and/or article  20 . That is, the magnetically attractable elements can be disposed within article  20  and electronic device  22  as for example within the housing of electronic device  22 . In this configuration, the housing can be formed of non-magnetic material such as plastic or non-ferrous metal such as aluminum. In this way, magnetic force lines can be configured to work through the walls of the housing. The magnetic attachment features do not disturb the physical appearance of the external surfaces of article  20  and electronic device  22 . The magnetically attractable elements in article  20  and electronic device  22  can be arranged to produce magnetic fields that can cooperate with each other to generate a magnetic attractive force that attaches article  20  and electronic device  22  together in the mating engagement. The magnetic attractive force being configured to generate a magnetic attraction force normal to engagement surface  26  between electronic device  22  and article  20 . 
     The magnetic attractive force between corresponding magnetic elements in article  20  and electronic device  22  can also be uniformly applied along engagement surface  26 . The uniformity of the overall magnetic attractive force along engagement surface  26  can be a result of the uniformity of the separation distance between corresponding magnetic elements in article  20  and electronic device  22 . The uniformity can also be a result of the consistency of magnetic flux density between corresponding magnetic elements in article  20  and electronic device  22 . The uniformity of net magnetic attachment can be facilitated by the surfaces of article  20  and electronic device  22  each forming a well matched fit to each other. For example, one surface can be flat or have a concave geometry whereas the other surface can have a matching conforming convex geometry. In this way, by fitting tightly together, a separation distance between each of the corresponding magnetic elements in article  20  and electronic device  22  can be reduced to a minimum. The conformity of surface shapes can also enhance the overall look and feel of article  20  and electronic device  22  by reducing or eliminating the appearance of a seam at engagement surface  26 . This seamless quality can provide an illusion of a single entity when article  20  and electronic device  22  are attached to each other. 
     In addition to enhancing the overall look and feel, the consistency of the separation distance between the magnetic elements can render the attachment force between article  20  and electronic device  22  uniform along engagement surface  26 . In this way, the engagement force can be uniformly distributed across engagement surface  26  preventing buckling, weak spots, and so on that might otherwise affect the overall integrity of the engagement between article  20  and electronic device  22 . 
       FIGS. 3A and 3B  are simplified perspective views of article  30  that can be releasably attached to an electronic device  32  via magnetic attachment system  34  and corresponding attachment system  36 . It should be noted that this particular embodiment is similar to the embodiment described in  FIGS. 2A ,  2 B except that the magnetic surfaces that were previously located at the side walls are now located on a face of electronic device  32  and, optionally, an opposing face on article  30 . For example, in the case of an electronic device including a display, the magnetic elements of magnetic attachment system  34  can be embedded behind the display surface. 
       FIG. 3B  shows article  30  and electronic device  32  magnetically attached to each to each other to form cooperating system  38 . As part of system  38 , electronic device  32  and article  30  can cooperate with each other to provide features not available by article  30  or electronic device  32  separately. For example, article  30  can take the form of a cover that can provide protective features. In one embodiment, protective cover can be used to support and protect electronic device  32  while being transported or stored (e.g., cover the display surface). Due to the releasable nature of the magnetic attachment between magnetic attachment systems  34  and  36 , article  30  can be easily detached when electronic device  32  is to be used and subsequently re-attached when desired. 
     The placement of the magnetic elements can be such that only certain magnetically sensitive elements within electronic device  32  are affected by the magnetic field generated by the embedded magnetic elements. For example, a Hall Effect sensor can be used to detect whether or not article  30  is magnetically attached to and covering all or a portion of the display of electronic device  32  using the magnetic field generated by a magnetic element located in article  30 . On the other hand, a magnetically sensitive element in electronic device  32  such as a compass that relies upon an external magnetic field (i.e., such as that provided by the Earth), must not be unduly affected by magnetic field lines generated by the embedded magnetic elements. Therefore, the magnetic elements can be limited to those locations in electronic device  32  positioned away from magnetically sensitive elements such as the compass. 
       FIGS. 4A and 4C  are simplified perspective views of article  40  that can be releasably attached to electronic device  42  via a magnetic system  44 . This embodiment is similar to that shown in  FIGS. 2A ,  2 B and  3 A,  3 B in that magnetic system  44  can include multiple magnetically attractable elements and that article  40  and electronic device  42  generally correspond to those mentioned in previous Figures. For example, one set of magnetically attractable magnetic elements  44   a  can be placed relative to a side of article  40  and electronic device  42  while a second set of magnetically attractable elements  44   b  can be placed relative to a face of article  40  and electronic device  42 . As shown in  FIG. 4B , cooperating system  46  can be formed by placing article  40  and electronic device  42  within proximity to each other such that magnetic elements  44   a  on the sides of article  40  and electronic device  42  magnetically attract each other in addition to magnetic elements  44   b  located at the face of electronic device  42  and article  40 . The overall magnetic attraction generated at the side and face can be sufficient to retain article  40  and electronic device  42  in a mating engagement to form cooperating system  46 . 
     In one embodiment, as shown in  FIG. 4C , cooperating system  46  is presented in an open configuration in which article  40  is used as a cover for electronic device  42  that can be opened and closed. That is, article  40  can act as a protective cover of electronic device  42 . In this embodiment, article  40  can include binding  48  that attaches along the side of electronic device  42  and flap  50  that attaches to the front face of electronic device  42  and more particularly, top face  52 . Top face  52  can correspond to a display. In one implementation, flap  50  can move relative to binding  48 . The moving can be widely varied. In one example, flap  50  can pivot relative to binding  48 . The pivot can be widely varied. In one example, the pivot can be enabled by a hinge mechanism. In another example, the pivot can be enabled by a fold. Furthermore, the flap can be rigid, semi-rigid or flexible. In this manner, article  40  can form an open configuration where flap  50  is positioned away from electronic device  42  (display  52  can be viewed) and a closed configuration where flap  50  is positioned adjacent electronic device  42  (display  52  is covered as represented by closed embodiment of  FIG. 4B ). In one embodiment, binding  48  is only located on one side while flap  50  is only located at top face  52 . In so doing, the other surfaces of electronic device  42  are left exposed. As a result, the beauty of the electronic device may be shown off while the article is attached to the electronic device. Further, it may leave better access for I/O and connectivity related functionality (e.g., buttons, connectors, etc.). 
     Although the purpose of the magnetic elements is similar, i.e., attach article to electronic device, it should be appreciated that these mechanisms can widely vary. In some cases, the magnetic fields may be configured differently. By way of example, the side mounted magnetic surface may provide a first magnetic force and the front facing magnetic surface may provide a second magnetic force that is different than the first magnetic force. This may be in part due to different holding requirements as well as different surface areas, i.e., available space, and its effect on internal components of the electronic device. In one example, the side mounted magnetic surface provides a greater holding force for securing the article to the electronic device, i.e., it is the primary securing force while the front facing magnetic surface is the secondary securing force. 
     In one example, flap  50  includes multiple sections that are semi-rigid and bend relative to one another so as to make the flap movable and flexible. In one embodiment, flap  50  can be folded into one or more different configurations, and in some cases can be held in these configurations using a magnetic system similar to what is described above. These and other embodiments will be described in greater detail below. Moreover, it should be appreciated that the described embodiments are not limited to covers and that other configurations can be used including for example as an accessory device used as a hanging apparatus, as a support mechanism for the electronic device to improve viewing the display and as a support mechanism for or inputting touch events at a touch sensitive portion of the display, and so on. 
     The electronic device and article can take many forms. For the remainder of this discussion, the electronic device is described in terms of a handheld portable computing device. Accordingly,  FIG. 5  shows a top perspective view of electronic device  100  in accordance with the described embodiments. Electronic device  100  can process data and more particularly media data such as audio, visual, images, etc. By way of example, electronic device  100  can generally correspond to a device that can perform as a smart phone, a music player, a game player, a visual player, a personal digital assistant (PDA), a tablet computer and the like. Electronic device  100  can also be hand held. With regards to being handheld, electronic device  100  can be held in one hand while being operated by the other hand (i.e., no reference surface such as a desktop is needed). Hence, electronic device  100  can be held in one hand while operational input commands can be provided by the other hand. The operational input commands can include operating a volume switch, a hold switch, or by providing inputs to a touch sensitive surface such as a touch sensitive display device or a touch pad. 
     Electronic device  100  can include housing  102 . In some embodiments, housing  102  can take the form of a single piece housing formed of any number of materials such as plastic or non-magnetic metal which can be forged, molded, or otherwise formed into a desired shape. In those cases where electronic device  100  has a metal housing and incorporates radio frequency (RF) based functionality, a portion of housing  102  can include radio transparent materials such as ceramic, or plastic. Housing  102  can be configured to enclose a number of internal components. For example, housing  102  can enclose and support various structural and electrical components (including integrated circuit chips) to provide computing operations for electronic device  100 . The integrated circuits can take the form of chips, chip sets, or modules any of which can be surface mounted to a printed circuit board, or PCB, or other support structure. For example, a main logic board (MLB) can have integrated circuits mounted thereon that can include at least a microprocessor, semi-conductor memory (such as FLASH), and various support circuits and so on. Housing  102  can include opening  104  for placing internal components and as necessary can be sized to accommodate display assembly for presenting visual content, the display assembly being covered and protected by protective layer  106 . In some cases, the display assembly can be touch sensitive allowing tactile inputs that can be used to provide control signals to electronic device  100 . In some cases, the display assembly may be a large prominent display area that covers a majority of the real estate on the front of the electronic device. 
     Electronic device  100  can include a magnetic attachment system that can be used to magnetically attach electronic device  100  to at least one other suitably configured object. The magnetic attachment system can include a number of magnetic attachment features distributed within and in some cases connected to housing  102 . For example, the magnetic attachment system can include first magnetic attachment feature  108  and second magnetic attachment feature  110  located on different sides of electronic device  100 . In particular, first magnetic attachment feature  108  can be located in proximity to side wall  102   a  of housing  102 . Second magnetic attachment feature  110  can be located within opening  104  near side walls  102   c  and  102   d  proximate to side wall  102   b  of housing  102 . By placing magnetic attachment feature  110  at opposite side walls, an amount of racking (or lateral movement) of a cover magnetically secured by attachment feature  110  can be substantially reduced. In those embodiments where electronic device  100  includes a display with cover glass  106  substantially filling opening  104 , second attachment feature  110  (also referred to as securing attachment feature  110 ) can be placed beneath cover glass  106 . It should be noted that without loss of generality, first magnetic attachment feature  108  will henceforth be referred to as device attachment feature  108 . 
     Although not expressly shown, it is understood that the various magnetic attachment features of the magnetic attachment system can be located at any appropriate location of housing  102 . For example, magnetic attachment features can be located at an interior bottom surface of housing  102  or along sides  102   c  and  102   d  of housing  102 . 
     As shown in  FIG. 6 , device attachment feature  108  and securing attachment feature  110  can each include one or more magnetic elements. In one example, device attachment feature  108  can multiple magnetic elements that can magnetically interact with each other to provide magnetic field  112  (only a portion of which is shown). In other words, the properties (shape, field strength, and so on) of magnetic field  112  can be based upon the interaction of the magnetic fields generated by each of the magnetic elements. In this way, the properties of magnetic field  112  can be altered simply by arranging the properties (i.e., physical layout, relative size, and constituent magnetic polarities) of each of the magnetic elements. For example, each of the magnetic elements can have varying sizes and can be disposed along an axis. In this way, the magnetic properties of each of the plurality of magnetic elements can act together to establish the overall properties of magnetic field  112 . 
     In some cases, the portion of magnetic field  112  that is used in the magnetic attachment between device attachment feature  108  and another device can be enhanced with the use of a magnetic shunt (not shown). The magnetic shunt can be formed of magnetically active material, such as steel or iron, and be placed in a position that causes magnetic field lines that would otherwise be directed away from the attachment region to be at least partially re-directed towards the attachment region. The re-direction of the magnetic field lines can have the effect of increasing the average magnetic flux density in the attachment region. 
     Device attachment feature  108  can operate in an active state as in well as an inactive state. Magnetic flux density B 112  can equal or exceed a magnetic flux density threshold B threshold  inside the exterior surface of housing  102  but not outside in the inactive state. In other words, magnetic flux density B 112  of magnetic field  112  at an exterior surface of housing  102  is less than a magnetic flux density threshold B threshold . Magnetic flux density threshold B threshold  representing a magnetic flux value below which magnetically sensitive devices (such a magnetic strip on a credit card) can remain substantially unaffected. In addition, the presence of a magnetically active material (such as steel) in the region outside of electronic device  100  will not by itself trigger device attachment feature  108  to transition from the inactive state to the active state. 
     The properties of magnetic field  112  can include at least field strength, magnetic polarity, and so on. The properties of magnetic field  112  can be based upon the combination of the magnetic fields from each of the magnetic elements included in magnetic attachment feature  108  The combined magnetic fields can form in the aggregate magnetic field  112 . For example, the magnetic elements can be arranged in such a way that the combination of the respective magnetic fields results in magnetic field  112  having desirable magnetic field properties (such as field strength). For example, the combination of one arrangement of magnetic elements can result in magnetic field  112  having characteristics (such a polarity and strength) that are for the most part symmetric about a particular axis (such as a geometric center line). 
     On the other hand, the magnetic elements can be arranged in such a way that the combination of the magnetic fields of the magnetic elements can result in magnetic field  112  having at least one property that is anti-symmetric about the center line. For example, a magnetic element on one side of the centerline can be positioned with a North magnetic pole pointing up whereas a corresponding magnetic element on the other side of the centerline can be arranged with a South magnetic pole pointing up. Hence, the magnetic properties of magnetic field  112  can be adjusted in any manner deemed appropriate to provide a desired mating engagement. For example, the magnetic properties of magnetic field  112  can be modified by arranging the magnetic elements in such a way that magnetic field  112  can cooperatively interact with another magnetic field (from another magnetic attachment system, for example). The cooperative interaction between the two magnetic fields can result in the two objects being magnetically attached to each other in a well-defined, precise, and repeatable manner. 
     The properties of magnetic field  112  can be stable. By stable it is meant that the properties of the magnetic field can remain essentially unchanged for an extended period of time. Hence, a stable version of magnetic field  112  can be created using magnetic elements having properties that are essentially constant (or nearly constant) over an extended period of time or at least any changes in one component is offset by a corresponding change in another component. The magnetic elements can be physically arranged in a fixed or at least substantially fixed configuration with respect other magnetic elements. For example, the magnetic elements can each have fixed sizes and polarities arranged in a specific order relative to each other providing the desired properties (shape, strength, polarity, etc.) of magnetic field  112 . Hence, depending upon the properties and the nature of the magnetic elements, the shape of magnetic field  112  can remain substantially unchanged over the extended period of time (such as the anticipated operating life of electronic device  100 ). 
     In some embodiments, however, the properties of magnetic field  112  can be varied by modifying a magnetic or other physical property of at least one of the magnetic elements. When at least one magnetic element has magnetic properties (e.g., a polarity or field strength) that can be modified, the resulting magnetic field can also be modified. Accordingly, in some embodiments at least one of the magnetic elements can be characterized as having dynamic magnetic properties. By dynamic it is meant that at least one magnetic property, such as polarity, can be modified. In this way, the magnetic field properties of the resulting magnetic field can also vary. The resulting magnetic field, in turn, can alter the magnetic characteristics of magnetic field  112  that, in turn, can alter how the magnetic attachment system causes the objects to magnetically attach to each other (alignment, orientation, centering, and so forth). An electromagnet is one example of such a magnetic element whose magnetic properties can be modified as desired. Other examples include a malleable non-magnetic substrate impregnated with magnetic dopant (such as magnetite). In this way, the malleable substrate can be formed into a physical shape that can affect the nature of the magnetic field produced by the magnetic dopant material. 
     Turning now to other aspects of the magnetic attachment system, securing attachment feature  110  can include one or more of magnetic elements  116 . When a plurality of magnetic elements is used, the arrangement of the plurality of magnetic elements  116  can be widely varied and can magnetically interact with a cooperating feature on another device. In one embodiment, the plurality of magnetic elements  116  associated with securing feature  110  can assist in securing at least a portion of another device otherwise attached to electronic device  100  by way of device attachment feature  108 . 
     At least some of the plurality of magnetic elements  116  can have a fixed size and polarity (along the lines of a simple bar magnet) whereas other of the plurality of magnetic elements  116  can have magnetic properties that can vary (such as an electromagnet) while still others can be shaped to provide specific magnetic characteristics. For example, at least one of the plurality of magnetic elements  116  can be positioned and shaped (if need be) to interact with a magnetically responsive circuit included in the other device. Hence, the magnetically responsive circuit can respond to the presence (or absence) of a particular magnetic element(s) of securing feature  110 . An example of the magnetically responsive circuit is described above with regards to the Hall Effect sensor(s)  118 . 
     It should be noted that the magnetic field generated by magnetic elements  116  should not extend so far that magnetically sensitive circuits within electronic device  100  (such as Hall Effect sensors  118 ) are adversely affected. This is particularly important since the magnetic field is not generally contained within housing  102  since at least a portion of the magnetic field must extend in the z direction in order to interact with the magnetically active portion of other devices. Therefore, the magnetic field in {x,y} must be limited in extent to avoid magnetically sensitive circuits such as Hall Effect sensor  118  and compass  120 . In one embodiment, the shaping of the magnetic field in {x,y} can be accomplished using what can be referred to as shaping magnets discussed in more detail below. Moreover, some or all of magnets  116  can be shaped (such as a trapezoid) that contours magnetic field lines between each of the magnets  116  to restrict the extent in {x,y} to avoid unduly affecting sensitive magnetic circuits such as compass  120 . 
     In a particular implementation, the magnetic elements of device attachment feature  108  can be grouped into distinct magnetic regions. In this way, the magnetic fields from the magnetic regions can superpose to form magnetic field  112 . The magnetic regions can include various magnetic elements that can be arranged into groups represented by magnetic elements  126  and  128 . By grouping the magnetic element into separate magnetic regions, the ability of the magnetic attachment system to provide a magnetic field having desired characteristics can be substantially enhanced. Magnetic elements  126  and  128  can interact with each other to form magnetic field  112 . In the one embodiment, the interaction can take the form of combination of magnetic properties of each of magnetic elements  126  and  128 . In some cases, the arrangement of magnetic elements  126  and  128  can be related to each other in order to provide magnetic field  112  with desired characteristics. For example, magnetic elements  126  can  128  can be arranged in such a way relative to one another that magnetic field  112  is anti-symmetric (or symmetric) about a horizontal center line of magnetic attachment feature  108 . In another embodiment, magnetic field  112  can be anti-symmetric (or symmetric) about a vertical center line of attachment feature  108 . In still another embodiment, magnetic field  112  can be anti-symmetric (or symmetric) both horizontally and vertically. 
       FIG. 7A  shows electronic device  100  in proximity to object  200  having magnetic attachment feature  202 . Magnetic attachment feature  202  of object  200  can include magnetic elements each generating an individual magnetic field that can interact with the other to form in the aggregate a resulting magnetic field. The resulting magnetic field can have magnetic characteristics (such as field strength and shape) that can interact with magnetic field  112  of electronic device  100  to attach electronic device  100  and object  200  together in a well-defined, precise, and repeatable manner without mechanical fasteners and nor require external assistance. Object  200  can take many forms including an accessory, peripheral, electronic device or the like. In one embodiment, object  200  can take the form of an electronic device along the lines of electronic device  100 . Accordingly, electronic device  100  and electronic device  200  can be magnetically attached to each other using device attachment feature  108  and magnetic attachment feature  202  to form a cooperative electronic system. The cooperative electronic system can be one in which electronic elements in electronic device  100  and corresponding electronic elements in electronic device  200  cooperate with the other to perform functions that cannot be performed by either of the electronic devices separately. In one embodiment, information can be passed between electronic devices  100  and  200 . 
     More specifically, magnetic attachment feature  202  can include at least magnetic elements  204  and  206  each of which can generate magnetic fields that cooperate with each other to provide magnetic field  208  (only a portion of which is shown). The properties of magnetic field  208  can be based upon the interaction of each of the plurality of magnetic elements  204  and  206 . In this way, magnetic field  208  can have properties based upon the physical layout, relative size, and constituent magnetic polarities of each of the plurality of magnetic elements  204  and  206 . For example, magnetic elements  204  and  206  can be disposed along a center line and have magnetic properties that superpose to provide magnetic field  208  with desired properties. 
     In addition to magnetic attachment feature  202 , accessory device  200  can further include magnetic attachment feature  216  that can be used to interact with securing attachment feature  110 . Magnetic attachment feature  216  can include a variety of magnetically active components. Some of the magnetic elements can take the form of magnetic elements arranged to cooperatively interact with corresponding magnetic elements in securing attachment feature  110 . Other of the magnetic element can be more passive in nature in that they provide a mechanism for completing a magnetic circuit with magnetically active elements in securing attachment feature  110 . An example of a magnetically passive element is a ferromagnetic material, such as iron or steel, that can be interact with a magnetic element actively providing an associated magnetic field. In this way, the ferromagnetic material can interact with the magnetic field to complete a magnetic circuit between the passive element in attachment feature  216  and the active element in securing attachment feature  110 . 
     As shown in  FIG. 7B , the overall magnetic attractive force F NET  between device  100  and device  200  at engagement surface  218  can be derived as the summation of all the net magnetic attractive forces F neti  for all actively coupled magnetic elements. In other words, the overall net magnetic attractive force F NET  satisfies the following equation:
 
F NET =Σ 1   n F neti  
 
where F neti  is the net magnetic attractive force for each of n components. In one embodiment, net magnetic attractive force F neti  is substantially perpendicular to that portion of engagement surface  218  intersected by magnetic field  112  and magnetic field  208 .
 
     In order to assure that overall magnetic attachment force F NET  is uniform along the engagement surface between device  100  and device  200 , the separation distances between each corresponding magnetic element in attachment features  108  and  202  are well controlled. The separation distance can be well controlled by, for example, shaping the magnetic elements to conform to the shape of the devices. For example, if device  100  has a spline (curved) shaped housing, the magnetic elements in device  100  can be shaped to conform to the curved shape. In addition, the magnetic elements can be formed in such a way that the magnetic vectors of corresponding magnetic elements align with each other. In this way, the magnitude and direction of the net magnetic attractive force can be controlled as desired. 
     One result of the aligning of the magnetic vectors is that the direction of the net magnetic force between each magnetic element can be well controlled. Moreover, by reducing the separation distance between corresponding magnetic elements to a minimum, the net attractive magnetic force F neti  between each magnetic element can be maximized. In addition, maintaining a substantially uniform separation distance between the various magnetic elements, a correspondingly uniform magnetic attachment force can be provided along engagement surface  218 . Moreover, by appropriately adjusting the corresponding magnetic vectors, F net  can be applied normally to the engagement surface. 
     In addition to minimizing the separation distance between corresponding magnetic elements, the magnetic flux density between the corresponding magnetic elements can be increased by using magnetic shunts. A magnetic shunt formed of magnetically active material such as iron or steel can be placed on or near a magnetic element having the effect of directing magnetic flux lines in a desired direction. In this way, for example, magnetic flux lines that would otherwise propagate in a direction away from a corresponding magnetic element can be partially re-directed towards a desired direction, such as towards a magnetic attachment region between the devices thereby increasing the overall magnetic flux density. Hence, increasing the available magnetic flux density between the magnetic elements can result in a substantial increase in the net magnetic attractive force. 
     For the remainder of this discussion, various embodiments of accessory device  200  are discussed. 
     In one embodiment, accessory device  200  can include a number of protective elements that can be used to protect certain aspects of electronic device  100 . For example, accessory device  200  can take the form of a protective cover. The protective cover can include a flap pivotally connected to a hinge assembly. The hinge assembly can, in turn, be coupled to electronic device  100  by way of accessory attachment feature  202 . In this way, the flap portion can be used as a protective cover to protect aspects of electronic device  100  such as a display. The flap can be formed of various materials such as plastic, cloth, leather, and so forth. The flap can be segmented in such a way that a segment of the flap can be lifted to expose a corresponding portion of the display. The flap can also include a functional element that can cooperate with a corresponding functional element in electronic device  100 . In this way, manipulating the flap can result in an alteration in the operation of electronic device  100 . 
     The flap can include magnetic material that can be used to activate a magnetically sensitive circuit in electronic device  100  based upon, for example, the Hall Effect. The magnetically sensitive circuit can respond by generating a signal that can, in turn, be used to alter an operating state of electronic device  100 . Since the cover can be easily attached directly to the housing of the tablet device without fasteners, the cover can essentially conform to the shape of electronic device  100 . In this way, the cover will not detract or otherwise obscure the look and feel of electronic device  100 . 
     Accessory device  200  can take the form of a support that can be used to enhance the functionality of electronic device  100 . For example, accessory device  200  can be configured to act as a display stand on which a display of electronic device  100  can be viewed at a comfortable viewing angle such as 60°-85°. In other words, when placed upon a horizontal surface such as a table or desk, accessory device  200  can support electronic device  100  in such a way that the visual content presented at the display can be viewed at about a viewing angle of approximately 60°-85°. Accessory device  200  can also take the form of a support that can be used to enhance the functionality of electronic device  100  in a keyboard mode. In the keyboard mode, accessory device  200  can be used to present a touch pad surface at an angle that is ergonomically friendly. In this way, input touch events can be applied (to a virtual keyboard, for example) at an angle that does not overtax a user&#39;s wrist, hands, arms, etc. 
     The remainder of this discussion will describe particular embodiments of devices that can use the magnetic attachment system. In particular,  FIG. 8A  and  FIG. 8B  show electronic device  100  presented in terms of tablet device  800  and accessory device  200  is shown as cover assembly  900  each in perspective top views. These elements may generally correspond to any of those previously mentioned. In particular,  FIGS. 8A and 8B  shows two perspective views of tablet device  800  and cover assembly  900 . For example,  FIG. 8A  shows magnetic surface  801  provided by device attachment feature  108  included in tablet device  800 . In this configuration, magnetic surface  801  does not exhibit sufficient intensity to adversely affect sensitive magnetic components in the proximity of tablet device  800 . Therefore, in this inactive mode, magnetic field  112  associated with magnetic surface  801  does not exceed B threshold .  FIG. 8B , on the other hand, is the view presented in  FIG. 8A  rotated about 180° to provide a second view of attachment feature  904  and its relationship with cover assembly  900 . 
     As shown in  FIG. 8A , tablet device  800  can include housing  802  that can enclose and support device attachment feature  108 . In order to not interfere with the magnetic field generated by device attachment feature  108 , at least that portion of housing  802  nearest device attachment feature  108  can be formed of any number of non-magnetic materials such as plastic or non-magnetic metal such as aluminum. Housing  802  can also enclose and support internally various structural and electrical components (including integrated circuit chips and other circuitry) to provide computing operations for tablet device  800 . Housing  802  can include opening  804  for placing internal components and can be sized to accommodate a display assembly or system suitable for providing a user with at least visual content as for example via a display. In some cases, the display assembly can include touch sensitive capabilities providing the user with the ability to provide tactile inputs to tablet device  800  using touch inputs. The display assembly can be formed of a number of layers including a topmost layer taking the form of transparent cover glass  806  formed of polycarbonate or other appropriate plastic or highly polished glass. 
     Although not shown, the display assembly underlying cover glass  806  can be used to display images using any suitable display technology, such as LCD, LED, OLED, electronic or e-inks, and so on. The display assembly can be placed and secured within the cavity using a variety of mechanisms. In one embodiment, the display assembly is snapped into the cavity. It can be placed flush with the adjacent portion of the housing. In this way, the display can present visual content that can include video, still images, as well as icons such as graphical user interface (GUI) that can provide information the user (e.g., text, objects, graphics) as well as receive user provided inputs. In some cases, displayed icons can be moved by a user to a more convenient location on the display. In some embodiments, a display mask can be applied to, or incorporated within or under cover glass  806 . The display mask can be used to accent an unmasked portion of the display used to present visual content and can be used to make less obvious device attachment feature  108  and securing attachment feature  110 . Cover  900  can include flap  902  and (not shown) flexible hinge  904  that can magnetically interact with magnetic attachment feature  108  to form a magnetic attachment force suitable for magnetically attaching cover  900  and tablet device  800 . Although not shown, in some embodiments, cover  900  can be folded about 360° about tablet device  800 . In this way, cover  900  can be in contact with rear surface  808  of housing  802 .  FIG. 8B  shows tablet device  800  and cover  900  rotated in such a way to show more clearly flexible hinge assembly  904 . 
     Cover assembly  900  is shown in  FIGS. 9A and 9B  attached to tablet device  800 .  FIG. 9A  shows cover assembly  900  attached to tablet device  800  in a fully closed configuration in which flap  902  fully covers cover glass  806  and the corresponding portion of the display assembly. On the other hand,  FIG. 9B  shows cover assembly  900  attached to tablet device  800  in an open configuration in which cover glass  806  is fully viewable. In one embodiment, flap  902  can have a size and shape in accordance with a top portion of tablet device  800  such as cover glass  806 . Flap  902  can be pivotally connected to flexible hinge assembly  904 . Flexible hinge assembly  904  can include magnetic attachment feature  202  in the form of an array of magnets arranged to magnetically interact with magnetic field  112  provided by magnetic attachment feature  108 . The magnetic attachment force between flexible hinge assembly  904  and attachment feature  108  can maintain cover assembly  900  and tablet device  800  in a proper orientation and placement vis-a-vis flap  902  and cover glass  806 . By proper orientation it is meant that cover assembly  900  can only properly attach to tablet device  800  having flap  902  and cover glass  806  aligned in a mating engagement. The mating arrangement between cover glass  806  and flap  902  is such that flap  902  covers substantially all of cover glass  806  when flap  902  is placed in contact with cover glass  806 . 
     In order to transition from the closed to the open configuration, releasing force F release  can be applied to flap  902 . Releasing force F release  can overcome the magnetic attractive force between attachment feature  216  in flap  902  and attachment feature  110  in tablet device  800 . Hence, cover assembly  900  can be secured to tablet device  800  until releasing force F release  is applied to flap  902 . In this way, flap  902  can be used to protect cover glass  806 . For example, cover assembly  900  can be magnetically attached to tablet device  900 . Flap  902  can then be placed upon and magnetically secured to cover glass  806  by the magnetic interaction between magnetic attachment features  110  and  216 . Flap  902  can be detached from cover glass  806  by the application of releasing force F release  directly to flap  902 . Releasing force F release  can overcome the magnetic attraction between magnetic attachment features  110  and  216 . Hence, flap  902  can then move away from cover glass  806  unhindered. In order to maintain a good magnetic attachment between flap  902  and magnetic attachment feature  110 , flap  902  can include a number of magnetic elements. Some of the magnetic elements in flap  902  can interact with corresponding magnetic elements in magnetic attachment feature  110 . The net magnetic attractive force generated between the magnetic elements can be strong enough to prevent inadvertent release of flap  902  from cover glass  806  during normal handling. The net magnetic attractive force, however, can be overcome by releasing force F release . It should be noted that using at least two magnetic attachment features  110  on either side of tablet device  800 , lateral movement of cover  900  (also referred to as racking) can be essentially eliminated. 
     In some embodiments, flap  902  can be unitary in appearance by which it is meant that flap  902  can appear as a single unit such that flap  902  can bend slightly if formed of flexible material. However, in other cases, flap  902  can include a number of segments joined to adjacent segments by associated folding regions that permit the segments to fold independently of each other as well as with respect to tablet device  800 . Accordingly,  FIG. 10A  shows a top view of a specific embodiment of cover assembly  900  in the form of cover assembly  1000 . Cover assembly  1000  can include body  1002 . Body  1002  can have a size and shape in accordance with cover glass  806 . Body  1002  can be formed from a single piece of foldable or pliable material. Body  1002  can also be divided into segments separated from each other by a folding region. In this way, the segments can be folded with respect to each other at the folding regions. 
     In one embodiment, body  1002  can be formed of layers of material attached to one another forming a laminate structure. Each layer can take the form of a single piece of material that can have a size and shape in conformance with body  1002 . Each layer can also have a size and shape that correspond to only a portion of body  1002 . For example, a layer of rigid or semi-rigid material about the same size and shape of a segment can be attached to or otherwise associated with the segment. In another example, a layer of rigid or semi-rigid material having a size and shape in accordance with body  1002  can be used to provide segmented cover assembly  1000  as a whole with a resilient foundation. It should be noted that the layers can each be formed of materials having desired properties. For example, a layer of segmented cover assembly  1000  that comes in contact with delicate surfaces such as glass can be formed of a soft material that will mar or otherwise damage the delicate surface. In another embodiment, a material such as micro-fiber can be used that can passively clean the delicate surface. On the other hand, a layer that is exposed to the external environment can be formed of a more rugged and durable material such as plastic or leather. 
     In a specific embodiment, body  1002  can be partitioned into a number of segments that can be widely varied. In the embodiment shown in  FIG. 10A , segmented body  1002  can be partitioned into three segments, segments  1004 ,  1006 , and  1008  each coupled to an adjacent segment by thinner, foldable portions  1010 . Each of the segments  1004 - 1008  can include one or more inserts disposed therein. By way of example, the segments can include a pocket region where the inserts are placed or alternatively the inserts may be embedded within the segments (e.g., insert molding). If pockets used, the pocket region can have a size and shape to accommodate corresponding inserts. The inserts can have various shapes but are most typically shaped to conform to the overall look of segmented body  1002  (e.g., rectangular). The inserts can be used to provide structural support for segmented body  1002 . That is, the inserts can provide stiffness to the cover assembly. In some cases, the inserts may be referred to as stiffeners. As such, cover assembly  1000  is relatively stiff except along the foldable regions that are thinner and do not include the inserts (e.g., allows folding) making segmented cover assembly  1000  more robust and easier to handle. In one embodiment segments  1004 ,  1006 , and  1008  can have a size relationship to each other such that a segments  1004 - 1008  can be used to form a triangular support structure. The triangular support structure can be used to enhance a user experience of tablet device  800 . 
     For example, if segmented body  1002  is constructed to have three independently foldable segments (segment  1004 , segment  1006 , and segment  1008 ), a triangular structure can be formed by coupling segment  1004  and segment  1008  (using magnets as described below or simply friction coupling). It should be noted that the properties of the triangular structure can vary in accordance with the relative sizes of the segments  1004 ,  1006 , and  1008 . In other words, when segments  1004 ,  1006 , and  1008  are about equal in width, then the triangular structure can take the form of an equilateral triangle, whereas when two segments are about of equal width, then the triangular structure can take on the shape of an isosceles triangle. In this way, the triangular structure can be shaped for a particular purpose. For example, in one configuration the triangular structure can be used to support tablet device  800  in a movie mode or in a keyboard mode. 
     In one embodiment, segmented body  1002  can include a number of magnets some of which can be used to form the triangular structure. For example, segment  1004  can include first edge attach magnets  1012  linearly arrayed along first edge  1014  of segmented body  1002  whereas segment  1008  can include second edge attach magnets  1016  linearly arrayed along second edge  1018  opposite to first edge  1014 . In this embodiment, first edge attach magnets  1012  and second edge attach magnets  1016  have a one to one correspondence in which each first edge attach magnet  1012  can be associated with a corresponding one of second edge attach magnets  1016 . Moreover, in order to create a maximum magnetic attractive force between first edge attach magnets  1012  and second edge attach magnets  1016 , each magnet pair can exhibit opposite magnetic polarities. For example, when first edge attach magnets  1012  are arranged in first polarity pattern (alternating) M 1  {P 1 , P 2 , P 1 , P 2 , P 1 , P 2 , P 1 , P 2 }, then second edge attach magnets  1016  can be arranged in complementary priority pattern M 2  {P 2 , P 1 , P 2 , P 1 , P 2 , P 1 , P 2 , P 1 }. In this way, a maximum magnetic attachment force can be realized between the two magnetic arrays while minimizing magnetic fringe effects at the ends of the magnetic arrays. In one embodiment, first edge attach magnets  1012  and second edge attach magnets  1016  can have dimensions of approximately (L×W×H) of 10 mm×5 mm×8 mm formed of neodymium (N35SH) grade magnets. It should be noted that the number of edge attach magnets can vary from as few as two to more than 16. 
     It should be noted that in some cases, it can be desirable to constrain a magnetic field provided by first edge attach magnets  1012  and second edge attach magnets  1014  in order to avoid or at least control adverse magnetic affects on sensitive magnetic circuits such as compass  120  (whose position is indicated in relation to first edge attach magnets  1012  when segmented body  1002  is in the fully closed configuration). In order to control the adverse affects of the magnetic field generated by first edge attach magnets  1012 , field shaping magnets  1022  can be placed in positions that can reduce a magnetic offset experienced by compass  120 . Moreover, as shown in insert  1024 , first edge attach magnets  1012  (as well as second edge attach magnets  1016 ) can be shaped in such a way that leakage magnetic flux Φ leakage  between the constituent magnets can be substantially reduced. In the embodiment shown in insert  1024 , magnets  1026  are trapezoidal in form that limits the amount of magnetic flux Φ leakage . In this way, the magnetic offset at compass  120  caused by first edge attach magnets  1012  can be maintained with an acceptable range. For example, the magnetic offset at compass  120  from edge attach magnets  1012  can be on the order of 10° or less at a reference location. 
     One approach to forming at least one triangular support structure can be to simply friction couple segment  1004  and segment  1008 . By friction couple it is meant that surface friction created between segments  1004  and  1008  when brought in direct contact can be sufficient to maintain the triangular structure even when used to support tablet device  800  in the movie mode or the keyboard mode. Alternatively, the triangular structure can be formed by bringing first edge attach magnets  1012  in proximity to second edge attach magnets  1016  thereby forming a magnetic circuit. It should be noted that in some embodiments, first edge attach magnets  1012  and second edge attach magnets  1016  are not required to overlay one another but merely be in proximity separated by distance “d” (shown in  FIG. 11 ) from one another to create the magnetic circuit. Therefore, by creating the magnetic circuit configured to maintain the integrity of the triangular structure, the triangular structure can be used for multiple purposes to enhance the functionality of tablet device  800 . 
     Segmented cover  1000  can also include holding magnets  1028  and  1030  that can be used to maintain segmented cover  1000  in a fixed position in relation to display  806  in the fully closed configuration. In other words, holding magnets  1028  and  1030  can reduce or even eliminate movement of cover  1000  from “side to side” (sometimes referred to as “racking”). In one embodiment, holding magnet  1030  can be oversized in relation to holding magnet  1028 . In this way, first portion  1030   a  of holding magnet  1030  (i.e., that portion of holding magnet  1030  that does not function as an edge attach magnet) can cooperate with holding magnet  1028  to reduce racking of cover  1000  whereas edge attach portion  1030   b  of holding magnet  1030  can function as part of first edge attach magnets  1012 . 
     In some cases, cover  1000  can also include magnets used to trigger magnetic sensors in tablet device  900 . For example, segment  1004  can include first sensor magnet  1032  and segment  1006  can include second sensor magnet  1034 . It should be noted that in some embodiments, first sensor magnet  1032  can be over-sized to prevent a false open condition in which tablet device  800  activates the display assembly even though body  1002  remains in the fully closed configuration. The false open condition can be triggered when body  1002  laterally moves (i.e., racking) to such an extent that a sensor disposed in tablet  800  can no longer detect the magnetic field generated by first sensor magnet  1032  causing the processor in tablet device  1032  to alter the operating state to active display mode. Therefore, the combination of oversizing of first sensor magnet  1032  and using holding magnets  1028  and  1030  to reduce racking, the incidence of false open condition can be greatly reduced. 
     In this arrangement, first sensor magnet  1032  can be detectable by a magnetically sensitive circuit (such as a Hall Effect sensor, or HFX) disposed within tablet  800 . In particular, the HFX can detect a magnetic field provided by sensor magnets  1032  and  1034  through protective layer  806 . In this way, a processor in tablet device  800  can use magnetic detection information to determine a spatial relationship between cover  1000  and tablet  800 . More specifically, the detection information can provide an indication that segment  1004  is folded away from tablet  1000  (when sensor magnet  1032  is not detected and sensor magnet  1034  is detected). In this way, the processor can alter operation of tablet device  800  in accordance with the spatial relationship between cover  1000  and tablet  800 . For example, when the processor determines that only segment  1004  is folded away to reveal a corresponding portion of the display assembly, then the processor can change the operation of tablet  800  to provide visual content only by the revealed portion of the display assembly in what is referred to as peek mode. In some embodiments, tablet device  800  can operate in what is referred to as extended peek mode when sensor magnets  1032  and  1034  are not detected but the processor can determine that cover  1000  is magnetically attached to tablet  800  (in other words, segments  1004  and  1006  are folded away from tablet device  800  to reveal a corresponding portion of the display assembly, but segment  1008  remains in place). In this way, tablet device  800  can present visual content in only that portion of the display assembly that is viewable (corresponding to folded away segments  1004  and  1006 ). 
     Cover  1000  can magnetically attach to tablet device  800  using flexible hinge assembly  1036  that can include flexible hinge  1038  and magnetic assembly  1040 . Flexible hinge assembly  1036  can be integrated in the sense that there flexible hinge assembly  1036  is formed as part of segmented cover  1000 . In some embodiments, flexible hinge assembly  1036  can be formed of the same material (fabric, leather, etc.) as is used to form a top portion of segmented cover  1000 . In this way, the visual effect can be one of continuity when viewing segmented cover  1000 . Further enhancing the sense of continuity is the wrap around nature of flexible hinge  1036 . By wrap around it is meant that material that forms body  1002  (and in particular a top portion formed of fabric, for example) can continue beyond edge  1018  (sometimes referred to as a tail) to form flexible hinge  1038  that can wrap around magnetic assembly  1040 . In this way, a sense of continuity between body  1002  and flexible hinge assembly  1036  can be achieved. 
     Flexible hinge assembly  1036  can include flexible hinge  1038  coupled to magnetic assembly  1040  configured to magnetically attach to magnetic attachment feature  108  in tablet device  800 . In one embodiment, magnetic assembly  1040  can include a plurality of magnets configured to form a magnetic attachment with corresponding magnets in magnetic attachment feature  108 . For example,  FIG. 10B  shows a representation of possible magnet arrays used to magnetically attach cover  1000  and tablet device  800 . In one embodiment, magnetic assembly  1040  can include magnetic array  1042  arranged in alternating pattern M3 as follows:
 
M3: {[P1,P2,P1],[P1,P2],[P2,P1],[P1,P2],[P2,P1,[P1,P2][P2,P1,P2]}
 
(where brackets [ ] indicate physically grouped magnets).
 
     On the other hand, magnetic attachment feature  108  disposed in tablet device  800  can include a corresponding magnetic array  1044  arranged in a manner that is complementary to alternative pattern M 3 . By complementary it is meant that magnetic polarities are inverted in that a magnet having a P 1  polarity will be paired with a magnet having a P 2  polarity and so forth. In this way, a maximum amount of magnetic attractive force between the two magnets can be realized with a minimum of magnetic fringing effects at either end of the magnetic array. 
     However, in still other embodiments as represented by magnetic array  1046 , specific magnets can be replaced by ferromagnetic blocks in order to conserve on the number of magnets used for magnetic attachment. For example, in one embodiment, a reduced number of magnets can be used in magnetic attachment feature  108  by replacing some magnets with ferromagnetic blocks (B) and can be arranged in polarity pattern M 4  as follows:
 
M4: {[P1,B,P1],[P1,P2],[P2,P1],[P1,P2],[P2,P1,[P1,P2][P2,B,P2]}
 
where B represents a ferromagnetic block formed of ferromagnetic material such as 1010 steel. It should be noted that the arrangement of magnets in either magnetic attachment feature  108  or magnetic assembly  1040  can be widely varied. Any limitations can be due primarily to the relationship between the magnetic arrays and the desired properties of the magnetic attachment.
 
       FIG. 11  shows a cross section view  1100  of flexible hinge assembly  1036  in an attachment configuration with tablet device  800  and cover  1000  in a folded configuration in accordance with the described embodiments. In particular, magnetic circuit  1102  can be formed by bringing first edge attach magnets  1012  and second edge attach magnets  1016  within distance “d” of each other. Magnetic circuit  1102  can provide sufficient magnetic force to maintain cover  1000  in the folded configuration (such as movie mode or keyboard mode). In some embodiments, magnetic circuit  1102  can be replaced by a friction coupling between edge  1012  and edge  1018 . In this way, friction couple can provide adequate support for maintaining cover  1000  in the folded configuration. 
     Flexible hinge  1038  can be formed as an extension of body  1002  in order to provide a more aesthetically pleasing look of continuity. Moreover, the flexible nature of flexible hinge  1038  provides for a smoother pivoting movement of cover body  1002  with respect to tablet device  800 . In one embodiment, protective layer  1048  can be provided as part of flexible hinge assembly  1036  that prevents any metal on metal contact between housing  802  and magnets  1050  in magnetic attachment feature  1040 . 
       FIG. 11  also illustrates representative magnetic interaction between edge attach magnets  1012  and  1016  in accordance with magnetic circuit  1102 . Magnetic circuit  1102  can be associated with magnetic attraction force F attraction . Magnetic attraction force  1104  can correspond with magnetic flux density associated with magnetic field lines  1106 . For example, the magnetic flux density associated with magnetic circuit  1102  in region A (where magnets  1012  and  1016  are closest together) can be greater than the magnetic flux density in region B where magnets  1012  and  1016  are further apart. In this way, magnetic attraction force  1104  between segment  1008  and  1004  can be strongest in region A. Moreover, a magnetic interaction between magnet  1012  and magnets  1050  and  108  can be such that net repulsive force Fr can be applied to segment  1004  that increases the net attachment force between segments  1004  and  1008 . In other words, the total attachment force between segments  1004  and  1008  can be the aggregate of magnetic attraction force F attraction  and magnetic repulsion force F repulsion . 
       FIGS. 12A-12D  show representative cross sectional views of segmented cover assembly  1000 /tablet device  800  along line AA shown in  FIG. 10A . In particular,  FIG. 12A  shows cover assembly  1000  in fully closed configuration  1200  in which interior surface  1204  of cover assembly  1000  comes in full contact with cover glass  806  of tablet device  800 . In fully closed configuration  1200 , Hall Effect sensor  118 - 1  can detect a magnetic field provided by sensor magnet  1032 . Concurrently Hall Effect sensor  118 - 2  can detect a magnetic field provided by sensor magnet  1034 . In this way, the processor can use the detection information provided by Hall Effect sensors  118 - 1 / 118 - 2  to determine a folded configuration of cover  1000  and the associated spatial relationship between cover  1000  and tablet device  800 . For example, using the detection information from Hall Effect sensors  118 - 1 / 118 - 2 , the processor determines that cover  1000  is in fully closed configuration  1200  where interior surface  1204  of cover  1000  is in full contact with cover glass  806 . In this way, once the processor has determined the spatial relationship between cover  1000  and tablet device  800 , the processor can cause tablet device  800  to operate in a manner in accordance with the determined spatial relationship. For example, when the processor determines that cover  1000  is in fully closed configuration  1200 , the associated spatial relationship is one where interior surface  1204  is in full contact with cover glass  806  thereby rendering the display and any visual content presented thereon as being un-viewable. Accordingly, the processor can direct that tablet device  800  disable or at least prevent visual from being presented by the un-viewable display. This can be referred to as a sleep mode. 
       FIG. 12B  shows partially open configuration  1202  where segment  1004  is folded away from cover glass  806  in such a way that portion  806 - 1  of display is rendered viewable. In partially open configuration  1202 , Hall Effect sensor  118 - 1  can not detect the magnetic field provided by sensor magnet  1032  since any magnetic field from magnet  1032  at Hall Effect sensor  118 - 1  is not greater that a minimum detection threshold. In this case, the processor can use detection information from Hall Effect sensor  118 - 2  and Hall Effect sensor  118 - 2  to deduce that only segment  1004  is folded away from cover glass  806  revealing portion  806 - 1  of cover glass  806 . In this way, only that portion of the display corresponding to portion  806 - 1  is viewable. In this situation, the processor can cause tablet device  800  to operate in a manner in accordance with partially open configuration  1202 . In one embodiment, tablet device  800  can operate in such a way that although the display remains fully active, visual content is presented only at the viewable portion of the display that corresponds to portion  806 - 1 . In an alternative embodiment, all but the viewable portion of the display can be de-activated. In this way, power can be conserved. In yet another alternative embodiment, visual content such as a graphical user interface, or GUI, can be altered in such a way to accommodate the reduced visual display area. For example, an amount of video resources allocated to display the GUI can be modified to take into account the reduced display area. The video resources can include number of pixels, pixel depth, and so forth. 
     It should be noted that in the case where neither Hall Effect sensors  118 - 1  or  118 - 2  detect either sensor magnet  1032  or  1034 , then cover  1000  can be in one of two possible states. A first state being the fully open configuration in which substantially all of cover glass  806  is revealed such that substantially of the display assembly can present visual content. However, a second state (also referred to as extended peek mode) can be associated with segments  1004  and  1006  being folded away from cover glass  806  but segment  1008  remains in place. The fully open configuration can be distinguished from the extended peek state by determining if cover  1000  is magnetically attached to tablet device  800 . This determination can be accomplished using magnetically sensitive circuits such as compass  120 . If a magnetic offset consistent with the presence of magnetic attachment feature  108  being in active mode is experienced by compass  120 , then the processor can infer that cover  1000  is magnetically attached to tablet device  800  and in so doing can alter the operation of tablet device  800  in accordance with the extended peek mode (such as presenting visual content at a viewable part of the display assembly). 
       FIGS. 12C and 12D  show embodiments whereby cover  1000  is folded in such a way that interior surface  1204  is in contact with rear surface  808  of tablet device  800  in first reverse folded configuration  1206 . Reverse folded configuration  1206  can be useful in those situations where tablet device  800  includes a camera or other such imaging device. In this way, a user can hold tablet device  800  using reverse folded configuration  1206  enabling use the display assembly as a viewfinder that can be used to compose an image or video. It should be noted that magnetic detection circuits such as Hall Effect sensor  118 - 1  and Hall Effect sensor  118 - 2  can be configured in such a way that in reverse folded configuration  1206 , only one of the magnetic detection circuits can detect a corresponding magnet in cover  1000 . For example, in reverse folded configuration  1206 , Hall Effect sensor  118 - 1  can detect magnet  1032  whereas Hall Effect sensor  118 - 2  can not detect magnet  1034 . This variation in detectability can be accomplished by, for example, varying the magnetic properties of the magnets or by providing a magnetic shield that reduces a magnetic field that emanates from rear surface  806  in the vicinity of Hall Effect sensor  118 - 2 . 
     Accordingly, when Hall Effect sensor  118 - 1  detects magnet  1032  and Hall Effect sensor  118 - 2  does not detect magnet  1034 , then tablet device  800  can operate in accordance with first reverse folded configuration  1206 . For example, in reverse folded configuration  1206 , tablet device  800  can operate in a manner that facilitates use of the display assembly as a view finder. In an alternative embodiment shown in  FIG. 12D  in which cover  1000  is in second reverse folded configuration also referred to as rear camera folded configuration  1208 , neither Hall Effect sensor  118 - 1  nor Hall Effect sensor  118 - 2  can detect magnets  1032  or  1034 . In this arrangement, an attachment detection device (such as compass  120 ) can be used to detect if cover  1000  is magnetically attached to tablet device  800 . In this way, when it is determined that tablet device  800  is attached to cover  1000  and cover  1000  is in second reverse folded configuration  1208 , then tablet device  800  can operate accordingly. Table 1 summarizes some of the relationships between detection signals provided by HFX sensors  118 - 1  and  118 - 2  and the corresponding spatial relationship between cover  1000  and tablet device  800  in terms of a folded configuration of cover  1000 . 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Folded Configuration 
                 HFX 118-1 Detection 
                 HFX 118-2 Detection 
               
               
                   
               
             
            
               
                 Fully Closed 
                 (D)etect 
                 (D)etect 
               
               
                 Peek Mode 
                 (N)o (D)etect 
                 (D)etect 
               
               
                 First Reverse Folded 
                 (D)etect 
                 (N)o (D)etect 
               
               
                 Reverse Camera Folded 
                 (N)o (D)etect 
                 (N)o (D)etect 
               
               
                   
               
            
           
         
       
     
     In addition to providing protection to tablet device  800 , segmented cover assembly  1000  can be manipulated to form useful support structures. Accordingly,  FIGS. 13 through 15  show useful arrangements of cover assembly  1000  in accordance with the described embodiments. 
       FIGS. 13A-13B  show a side view of a segmented cover configured to support a tablet device in a keyboard state. As shown in  FIGS. 13A and 13B , segmented cover assembly  1000  can be folded into first triangular structure  1300  by forming in one embodiment, magnetic circuit  1102  by bringing segment  1004  and  1008  in proximity to each other (it should be noted that a friction coupling between the segments can also suffice to form triangular structure  1300 ). Triangular structure  1300  can be formed that can be used in many ways to augment tablet device  800 . For example, triangular structure  1300  can be used to support tablet device  800  in such a way that a touch sensitive surface disposed beneath cover glass  806  is positioned relative to a support surface at an ergonomically advantageous angle. In this way, using the touch sensitive surface can be a user friendly experience. This is particularly relevant in those situations where the touch sensitive surface is used over an extended period of time. For example, a virtual keyboard can be presented at the touch sensitive surface. The virtual keyboard can be used to input data to tablet device  800 . By using triangular structure  1300  to support tablet device  800  at the ergonomically friendly angle, the deleterious effects of repetitive movements can be reduced or even eliminated. In the described embodiment, presentation angle θ can be in the range of 5° to 15°.  FIG. 13B  shows an alternative embodiment where cover  1000  is folded into second triangular structure  1302  in which segment  1004  is viewable in contrast to first triangular structure  1300  where segment  1004  was obscured from view by tablet device  800  and segment  1008  is viewable. 
       FIGS. 14A and 14B  shows another folded configuration of segmented cover assembly  1000  in which triangular support structure  1400  can be used to support tablet device  800  in a viewing state. By viewing state it is meant that triangular structure  1400  can support tablet device  800  in such a way that the display assembly can present visual content (visual, stills, animation, etc.). For example, in a first display configuration triangular support structure can support tablet device  800  such that the display assembly can present visual content at a presentation angle of about 65° to about 85°. In this “kickstand” state, visual content can be presented for easy viewing.  FIG. 14B  illustrates another arrangement of cover  1000  in the form of triangular support structure  1402  in which tablet device  800  can be supported in manner such that the display assembly presents visual content.  FIG. 14C  shows a front view of tablet device  800  supported in the viewing state in accordance with the described embodiments. 
       FIGS. 15A-15B  show configuration  1500  of cover assembly  1000  and tablet device  800  illustrating what is referred to as a peek mode of operation of tablet device  800 . More particularly, when segment  1004  is lifted from glass cover  806 , sensors in tablet device  800  can detect that segment  1004  and only that segment has been lifted from glass layer  806 . Once detected, tablet device  800  can activate only the exposed portion  1502  of the display. For example, tablet device  800  can utilize a Hall Effect sensor to detect that segment  1004  has been lifted from glass cover  806 . Additional sensors, such additional Hall Effect sensor or other type sensors such as optical sensors (ambient light sensor, for example) can then detect if only segment  1004  has been lifted or if additional segments have been lifted. 
     As shown in  FIG. 15B , when tablet device  800  has determined that only segment  1004  has been lifted, then tablet device  800  can change operating state to “peek” state in which only the exposed portion  1502  of the display actively presents visual content in the form of icons  1504 . Hence, information in the form of visual content such as time of day, notes, and so forth can be presented for viewing on only that portion of display viewable. Once the sensors detect that segment  1004  has been placed back on glass layer  806 , tablet  800  can return to the previous operational state such as a sleep state. Furthermore, in another embodiment, when an icon arranged to respond to a touch is displayed, then that portion of a touch sensitive layer corresponding to the visible portion of the display can also be activated. 
     Furthermore, as additional segments are lifted from cover glass  806  to further expose additional portions of cover glass  806 , additional portions of the display can be activated corresponding to the lifted segments. In this way, in the “extended” peek mode, additional visual information can be presented in the portions of the display activated. In this way, as segments are lifted from cover glass  806 , additional segments of the display can be activated providing the extended peek modes in accordance with the number of foldable segments. Alternatively, the tablet device  900  can respond to the signals from the Hall Effect sensor(s) by simply powering up the display when the flap is moved away from the display and power down (sleep) when the display is covered by the flap. 
       FIG. 16  shows an exploded view  1600  of segmented cover  1000 . Bottom layer  1602  can come in direct contact with a protected surface such as a cover glass for a display. Bottom layer  1602  can be formed of a material that can passively clean the protected surface. The material can be, for example, a microfiber material. Bottom layer  1602  can be attached to stiffening layer  1604  formed of resilient material such as plastic. Stiffening layer  1604  can, in turn, be adhesively attached to inserts  1606  to form a laminate structure. Inserts  1606  can be formed of resilient material such as plastic. It should be noted that although not shown, some of inserts  1606  can accommodate embedded components such as holding magnet  1028 , sensor magnets  1032  and  1034 , and so on. Edge support ring  1608  can be used to provide lateral stability to cover  1000 . Magnetic assembly  1040  can be attached to flexible hinge portion  1038  using adhesive layers  1610 . Magnetic assembly  1040  can include magnets  1050  supported by span  1608 . Span  1612  can be formed of a strong resilient material such as 304 SUS. It should be noted that in some embodiments, metal portions of  1612  can be sand-blasted in order to facilitate bonding between span  1612  and protective layer  1602  using adhesive layers  1616 . In a particular embodiment, span  1612  can be attached to protective layers  1602  using pressure sensitive adhesive, or PSA. An additional laminate structure can be formed of resilient material  1616  and top layer  1618 . In some embodiments, an intervening layer of material can be provided having a knitted structure that can aid in the attachment of top layer  1618  to resilient material  1616 . Top layer  1618  can be formed of many materials such as plastic, leather, and so forth in keeping with the overall look and feel of tablet device  800 . In order to provide additional structural support, edge stiffener ring  1608  can be used to reinforce edges of cover  1000 . Edge stiffener ring  1608  can be formed of plastic or other rigid or semi-rigid material. It should be noted that in order to preserve the aesthetic look of cover  1000 , cosmetic finish  1620  can be used to cover portions of magnetic assembly  1040 . 
       FIG. 17  is a block diagram of an arrangement  1700  of functional modules utilized by an electronic device. The electronic device can, for example, be tablet device  900 . The arrangement  1700  includes an electronic device  1702  that is able to output media for a user of the portable media device but also store and retrieve data with respect to data storage  1704 . The arrangement  1700  also includes a graphical user interface (GUI) manager  1706 . The GUI manager  1706  operates to control information being provided to and displayed on a display device. The arrangement  1700  also includes a communication module  1708  that facilitates communication between the portable media device and an accessory device. Still further, the arrangement  1700  includes an accessory manager  1710  that operates to authenticate and acquire data from an accessory device that can be coupled to the portable media device. 
       FIG. 18  is a block diagram of an electronic device  1750  suitable for use with the described embodiments. The electronic device  1750  illustrates circuitry of a representative computing device. The electronic device  1750  includes a processor  1752  that pertains to a microprocessor or controller for controlling the overall operation of the electronic device  1750 . The electronic device  1750  stores media data pertaining to media items in a file system  1754  and a cache  1756 . The file system  1754  is, typically, a storage disk or a plurality of disks. The file system  1754  typically provides high capacity storage capability for the electronic device  1750 . However, since the access time to the file system  1754  is relatively slow, the electronic device  1750  can also include a cache  1756 . The cache  1756  is, for example, Random-Access Memory (RAM) provided by semiconductor memory. The relative access time to the cache  1756  is substantially shorter than for the file system  1754 . However, the cache  1756  does not have the large storage capacity of the file system  1754 . Further, the file system  1754 , when active, consumes more power than does the cache  1756 . The power consumption is often a concern when the electronic device  1750  is a portable media device that is powered by a battery  1774 . The electronic device  1750  can also include a RAM  1770  and a Read-Only Memory (ROM)  1772 . The ROM  1772  can store programs, utilities or processes to be executed in a non-volatile manner. The RAM  1770  provides volatile data storage, such as for the cache  1756 . 
     The electronic device  1750  also includes a user input device  1758  that allows a user of the electronic device  1750  to interact with the electronic device  1750 . For example, the user input device  1758  can take a variety of forms, such as a button, keypad, dial, touch screen, audio input interface, visual/image capture input interface, input in the form of sensor data, etc. Still further, the electronic device  1750  includes a display  1760  (screen display) that can be controlled by the processor  1752  to display information to the user. A data bus  1766  can facilitate data transfer between at least the file system  1754 , the cache  1756 , the processor  1752 , and the CODEC  1763 . 
     In one embodiment, the electronic device  1750  serves to store a plurality of media items (e.g., songs, podcasts, etc.) in the file system  1754 . When a user desires to have the electronic device play a particular media item, a list of available media items is displayed on the display  1760 . Then, using the user input device  1758 , a user can select one of the available media items. The processor  1752 , upon receiving a selection of a particular media item, supplies the media data (e.g., audio file) for the particular media item to a coder/decoder (CODEC)  1763 . The CODEC  1763  then produces analog output signals for a speaker  1764 . The speaker  1764  can be a speaker internal to the electronic device  1750  or external to the electronic device  1750 . For example, headphones or earphones that connect to the electronic device  1750  would be considered an external speaker. 
     The electronic device  1750  also includes a network/bus interface  1761  that couples to a data link  1762 . The data link  1762  allows the electronic device  1750  to couple to a host computer or to accessory devices. The data link  1762  can be provided over a wired connection or a wireless connection. In the case of a wireless connection, the network/bus interface  1761  can include a wireless transceiver. The media items (media assets) can pertain to one or more different types of media content. In one embodiment, the media items are audio tracks (e.g., songs, audio books, and podcasts). In another embodiment, the media items are images (e.g., photos). However, in other embodiments, the media items can be any combination of audio, graphical or visual content. Sensor  1776  can take the form of circuitry for detecting any number of stimuli. For example, sensor  1776  can include a Hall Effect sensor responsive to external magnetic field, an audio sensor, a light sensor such as a photometer, and so on. 
     The magnetic attachment feature can be used to magnetically attach at least two objects. The objects can take many forms and perform many functions. When magnetically attached to each other, the objects can communicate and interact with each other to form a cooperative system. The cooperating system can perform operations and provide functions that cannot be provided by the separate objects individually. For example, at least a first object and a second object can be magnetically attached to each other such that the first object can be configured to provide a support mechanism to the second object. The support mechanism can be mechanical in nature. For example, the first object can take the form of a stand that can be used to support the second object on a working surface such as a table. In another example, the first object can take the form of a hanging apparatus. As such, the first object can be used to hang the second object that can then be used as a display for presenting visual content such as a visual, still images like a picture, art work, and so on. The support mechanism can also be used as a handle for conveniently grasping or holding the second object. This arrangement can be particularly useful when the second object can present visual content such as images (still or visual), textual (as in an e-book) or has image capture capabilities in which case the second object can be used as an image capture device such as a still or visual camera and the first object can be configured to act as a support such as a tripod or handle. 
     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 non-transitory computer readable medium. The computer readable medium is defined as 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, 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 target 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. 
     The advantages of the embodiments described are numerous. Different aspects, embodiments or implementations can yield one or more of the following advantages. Many features and advantages of the present embodiments are apparent from the written description and, thus, it is intended by the appended claims to cover all such features and advantages of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, the embodiments should not be limited to the exact construction and operation as illustrated and described. Hence, all suitable modifications and equivalents can be resorted to as falling within the scope of the invention.

Metadata:
Filing Date: 20140925
Publication Date: 20150707
Grant Date: 20150707
Priority Date: 20120808
Inventors: SARTEE JARED A.
SMITH SAMUEL G.
BALAJI SANTHANA K.
OW FLORENCE W.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/1677", "inventive": true, "first": true, "tree": "[]"}, {"code": "A45C11/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "A45C11/003", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1637", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1677", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C11/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/0252", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1675", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T24/32", "inventive": false, "first": false, "tree": "[]"}, {"code": "A45C2011/003", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F41/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02B60/1242", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/3265", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49826", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49826", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/3265", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/3265", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49826", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1675", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0266", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C11/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02D10/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1677", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0206", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1677", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T24/32", "inventive": false, "first": false, "tree": "[]"}, {"code": "A45C13/1069", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/0252", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49826", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1637", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1675", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0206", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/16", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F41/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0266", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C11/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/0252", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1637", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/0252", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02D10/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/3265", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T24/32", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T24/32", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K5/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/3265", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1677", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01F7/0252", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1637", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1637", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 50065774