PATENT DOCUMENT

Publication Number: US-12040643-B2
Application Number: US-202117394626-A
Country: US
Kind Code: B2

Title: Magnetically attachable charging devices

Abstract:
Attachment devices that can secure a phone or other electronic device in place in a vehicle or other structure. One example can provide an attachment device that can include a stalk portion to attach to a surface or structure in a vehicle, such as a vent cover, dashboard, monitor, cup holder or other surface or structure. The attachment device can further include an attachment feature to provide for an attachment to the electronic device. Further examples can provide power for a phone or other electronic device.

Claims:
What is claimed is: 
     
       1. An attachment device comprising:
 an enclosure formed by a contacting surface and a back plate; 
 a magnet array in the enclosure; 
 a mid-plate; 
 a stalk attached to the mid-plate, where the mid-plate is attached to the back plate; and 
 a front enclosure having an opening for the stalk, the front enclosure covering the mid-plate. 
 
     
     
       2. The attachment device of  claim 1  wherein the stalk comprises a grip, where the grip can form a physical connection to a structure to hold the attachment device in place. 
     
     
       3. The attachment device of  claim 2  wherein the contacting surface comprises a layer of silicone. 
     
     
       4. The attachment device of  claim 3  wherein the grip comprises a layer of silicone. 
     
     
       5. The attachment device of  claim 1  further comprising a coil in the enclosure, the coil arranged to transfer power to an electronic device that is attached to the attachment device. 
     
     
       6. The attachment device of  claim 5  further comprising near-field communication circuitry and components. 
     
     
       7. The attachment device of  claim 6  wherein the near-field communication circuitry and components comprises a tag and a capacitor. 
     
     
       8. An attachment device comprising:
 an enclosure; 
 a magnet array in the enclosure; 
 an alignment structure separate from the magnet array, where the alignment structure aligns an electronic device to the attachment device in a single orientation; and 
 a mounting structure to attach to a vehicular surface. 
 
     
     
       9. The attachment device of  claim 8  wherein the alignment structure comprises a magnet. 
     
     
       10. The attachment device of  claim 9  further comprising:
 a coil in the enclosure, the coil arranged to transfer power to the electronic device. 
 
     
     
       11. The attachment device of  claim 10  wherein the coil is laterally surrounded by the magnet array. 
     
     
       12. The attachment device of  claim 11  wherein the magnet array is configured to hold the electronic device adjacent to the attachment device in any one of a number of orientations. 
     
     
       13. The attachment device of  claim 12  wherein the magnet array is configured to hold the electronic device adjacent to the attachment device in any rotational orientation. 
     
     
       14. The attachment device of  claim 13  wherein the magnet array is configured to move between a first position in the enclosure and a second position in the enclosure, wherein the first position is located between the second position and a contacting surface of the enclosure. 
     
     
       15. The attachment device of  claim 14  wherein the contacting surface comprises silicone. 
     
     
       16. An attachment device comprising:
 an enclosure having a contacting surface; 
 a mounting structure comprising a grip to attach to a vehicular surface, where the mounting structure is attached to the enclosure; and 
 a magnet array in the enclosure wherein the magnet array is configured to move between a first position in the enclosure and a second position in the enclosure, wherein the first position is located between the second position and the contacting surface of the enclosure. 
 
     
     
       17. The attachment device of  claim 16  further comprising a connector receptacle located on the surface of the attachment device. 
     
     
       18. The attachment device of  claim 17  further comprising:
 an alignment magnet separate from the magnet array, where the alignment magnet aligns an electronic device to the attachment device in a single orientation. 
 
     
     
       19. The attachment device of  claim 18  further comprising near-field communication circuitry and components. 
     
     
       20. The attachment device of  claim 19  wherein the near-field communication circuitry and components comprises a tag and a capacitor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of and priority to United States provisional application numbers 63/081,812, filed Sep. 22, 2020, and 63/061,783, filed Aug. 5, 2020, which are incorporated by reference. 
    
    
     BACKGROUND 
     The number of types of electronic devices that are commercially available has increased tremendously the past few years and the rate of introduction of new devices shows no signs of abating. Devices such as tablet computers, laptop computers, desktop computers, all-in-one computers, cell phones, storage devices, wearable-computing devices, portable media players, portable media recorders, navigation systems, monitors, adapters, and others, have become ubiquitous. 
     As a result of the ubiquity and increasing functionality of these electronic devices, they are now a constant companion for many. They are often used during or in conjunction with many daily activities, either while performing an activity or in a manner that supplements an activity. 
     Driving is example of an activity where an electronic device is used in a supplementary manner. An electronic device, such as a phone, can be very useful while driving to provide entertainment, such as music, or to provide information, such as maps and navigation instructions. Such an electronic device can be useful for both a driver and a passenger of the vehicle. 
     Unfortunately, these phones or other electronic devices can move inside a vehicle during sharp turns or sudden stops. This can simply annoy a user, or it can become dangerous. Accordingly, it can be desirable to provide attachment devices that can securely attach a phone or other electronic device to a structure or surface of the vehicle. Another type of distraction can arise when a battery on a phone or other electronic device runs low or is not able to power the device. Accordingly, it can be desirable that some attachment devices have the capability of charging a phone or other electronic device. 
     Thus, what is needed are attachment devices that can secure a phone or other electronic device in place in a vehicle. It can also be desirable that these attachment devices be able to provide power to the phone or other electronic device. 
     SUMMARY 
     Accordingly, embodiments of the present invention can provide attachment devices that can secure a phone or other electronic device in place in a vehicle. Further embodiments can provide attachment devices that are also able to provide power to the phone or other electronic device. 
     An illustrative embodiment of the present invention can provide attachment devices having one or more attachment features for attaching to a phone or other electronic device. Once attached to an electronic device, the attachment device can secure the electronic device in place in a vehicle or other location, can provide charging for a battery of the electronic device, can be identified by the electronic device, or any combination of these. 
     These and other embodiments of the present invention can provide an attachment device that can include a stalk or other portion to attach to a surface or structure in a vehicle, such as a vent cover, dashboard, monitor, cup holder or other surface or structure. The attachment device can further include an attachment feature to provide for an attachment to an electronic device. In this way, an electronic device can be attached to a surface or structure in a vehicle through the attachment device. 
     These and other embodiments of the present invention can provide attachment devices having various attachment features, where an attachment feature can secure a phone or other electronic device to a contacting surface or structure of an attachment device. These attachment features can include one or more magnets, such as a magnet array, behind or at the contacting surface of the attachment device. This magnet array, or other magnet or magnetic structure (referred to here as a magnet array), can be a fixed magnet array positioned in an enclosure of the attachment device that forms a module of the attachment device. The magnet array can include one or more magnets. This magnet array can be attracted to a corresponding magnet array or other magnetic structure in or otherwise associated with an electronic device that is, or is being, attached to the contacting surface of the attachment device. 
     This magnet array can alternatively be a moving magnet array. The moving magnet array can be positioned in the enclosure such that the moving magnet array can move in a direction that is orthogonal (or at least nonparallel) to the contacting surface. The moving magnet array can also or instead move parallel to the contacting surface. The moving magnet array can be attracted to a corresponding magnet array in or otherwise associated with an electronic device that is, or is being, attached to the contacting surface of the attachment device. For example, the moving magnet array can be attracted to a corresponding magnet array in a case of the electronic device. As the electronic device is brought into proximity, the moving magnet array can move to a position in the enclosure such that it is closer to the electronic device, thereby increasing the magnetic attraction between the moving magnet array and the corresponding magnet array in the electronic device. 
     The fixed or moving magnet array in the attachment device can be formed of one or more rare earth magnets, one or more magnetized ferromagnetic materials, or other magnetic, magnetically conductive, or magnetizable material. The fixed or moving magnet array can instead be, or can include, a magnetically conductive structure that is not itself magnetic but can guide field lines from one or more magnets in the electronic device or elsewhere in the attachment device. The magnets in either or both the attachment device and electronic device can have various orientations. For example, they can have the same orientations, they can have alternating orientations, or their orientations can have other arrangements. 
     These and other embodiments of the present invention can provide attachment devices having other attachment features, such as one or more alignment structures that can attach an electronic device to an attachment device in a specific orientation, such as a portrait or landscape orientation. The alignment structures can be formed of one or more magnets placed in specific positions and having specific orientations. 
     These and other embodiments of the present invention can provide attachment devices having other attachment features, such as one or more high-friction or high-stiction contacting surfaces. The high-friction surfaces can cover a fixed magnet array at a contacting surface or portion thereof. The high-friction surfaces can cover a surface of a moving magnetic structure, such as a contacting surface or a portion thereof. The high-friction surfaces can engage a surface on or associated with an electronic device to increase a shear force needed to remove the electronic device from the attachment device. The high-friction surfaces can be formed of an elastomer, plastic, PVC plastic, rubber, silicon rubber, urethane, polyurethane, polycarbonate (PC), nitrile, neoprene, silicone, or other material. Some or all of the high-friction surfaces, such as a contacting surface, can also or instead be formed using an adhesive. Using an adhesive can increase both a shear force and a normal force needed to remove the electronic device from the attachment device. 
     These and other embodiments of the present invention can provide attachment devices having various alignment features where the alignment features help to align an electronic device to an attachment device. These alignment features can include markings, guides, raised features, or other identifying or mechanical features. One or more magnets, whether fixed or moving, or other magnetic structure, can be used as such an alignment feature. One or more magnets used as an alignment feature can be included as part of the above magnet array, or can be separate from the magnet array. 
     The attachment device enclosure can further house an inductive coil for providing inductive charging to an electronic device. The enclosure can further house shielding to magnetically isolate the inductive coil from the magnet array and to improve inductive coupling between the coil in the attachment device and a corresponding coil of a power receiving phone or electronic device. Control circuitry that receives an input power supply and generates alternating currents through the inductive coil can also be included in the enclosure or elsewhere in the attachment device. These alternating currents can generate a time-varying magnetic flux in the corresponding coil in an electronic device attached to the attachment device. The time-varying magnetic flux can generate currents in the corresponding coil that can be used to charge a battery in the electronic device. 
     The control circuitry can also sense currents in the coil in the attachment device that are induced by the corresponding coil in the electronic device. This can allow the control circuitry to read data transmitted by the electronic device. Specifically, a drive current to the corresponding coil can be modulated in order to transmit data to the attachment device. The modulation can be in amplitude, phase, frequency, or a combination thereof. For example, the drive current can be modulated in an on-off manner to transmit data. This modulation can generate a time-varying magnetic field that can induce currents in the coil in the attachment device. The control circuitry can read these induced currents to receive data from the electronic device. The data transmitted to the attachment device by the electronic device can include identification information for the electronic device, charge status, charging level requests, and other information. This data can be received by the attachment device and used in determining whether power should be delivered to the electronic device and in what amount. 
     Data can similarly be transmitted from the attachment device to the electronic device as well. Specifically, a drive current to the coil in the attachment device can be modulated in order to transmit data to the electronic device. The modulation can be in amplitude, phase, frequency, or a combination thereof. For example, the drive current can be modulated in an on-off manner to transmit data. This modulation can generate a time-varying magnetic field that can induce currents in the coil in the electronic device. This data can include identification and charge capability information about the attachment device. 
     Power and data can be received by an attachment device through a cable. Data can also be provided by the attachment device over this cable. The cable can be tethered to circuitry and components in the attachment device, or the cable can include a connector insert that can be inserted into a connector receptacle in the attachment device. The connector receptacle can be located in the enclosure or other portion of the attachment device. The cable can provide a power providing connection to the attachment device from a power converting brick, battery pack, external electronic device, or other power supply source. The cable can also provide data between the attachment device and a second electronic device, where the second electronic device is a different device than the electronic device attached to the contacting surface of the attachment device. 
     The attachment device enclosure can further house near-field communication circuitry and components, such as a transmitter including a near-field communication tag and capacitors. The near-field communication circuitry and components can allow an electronic device to detect and identify the attachment device. This recognition can prompt the electronic device to perform one or more activities. For example, the electronic device can launch one or more applications in response to this recognition. Various software and control features can be implemented in these and other embodiments of the present invention. The software and control features can be implemented in an attachment device, an electronic device attached to the attachment device, or in other devices associated with the electronic device or a vehicle to which the attachment device is attached, by circuitry or components in an area surrounding the attachment device or elsewhere, or by a combination of these. 
     These and other embodiments of the present invention can provide attachment devices having additional features that can increase their usefulness. For example, an attachment device can include a stalk to attach the attachment device to a surface or structure in or associated with a vehicle. This stalk can include a ball-joint or other mechanism that can allow a phone or other electronic device attached to a contacting surface of the attachment device to be rotated and titled for easy viewing. For example a backside of an electronic device can contact a contacting surface for an attachment device. A screen on a front side of the electronic device can then be rotated and tilted for easy viewing. 
     In these and other embodiments of the present invention, these structures can be formed of various materials in various ways. Some or all of each contacting surface shown here, or otherwise utilized by an embodiment of the present invention, can be formed of an elastomer, plastic, PVC plastic, rubber, silicon rubber, urethane, polyurethane, nitrile, polycarbonate, neoprene, silicone, or other material. The plates, enclosures, other enclosure and housing portions, shown here or otherwise utilized by an embodiment of the present invention, can be formed of a metal, such as stainless steel or aluminum, plastic, nylon, or other conductive or nonconductive material, such as a plastic. They can be formed using computer numerical control (CNC) or other type of machining, stamping, metal injection molding (MIM), or other technique. Ferritic portions, such as coil ferrites and bottom ferrites, can be formed of a material that has high magnetic permeability, such as stainless steel, ferritic stainless steel, oxides of iron, manganese, zinc, or other material or combination of materials. One or more e-shields can be included, for example between a coil and a contacting surface, and can be formed of a layer of copper or other conductive material to intercept electric fields between a coil in an attachment device and a corresponding coil in an electronic device, and can have a low magnetic permeability to pass magnetic fields between the coil and the corresponding coil. An e-shield can include breaks to prevent the formation of eddy currents. Control circuitry can be located on boards that can be formed of FR-4 or other material. Adhesive layers used here can be formed of a pressure-sensitive adhesive, a heat-activated film, or other type of adhesive. 
     In these and other embodiments of the present invention, portions of the attachment devices can be conductive. These conductive portions, such as shields, return plates, backplates, and other portions can be formed using stamping, forging, metal-injection molding, 3-D printing, CNC or other machining, or other manufacturing process. They can be formed of a material that has high magnetic permeability, such as stainless steel, ferritic stainless steel, oxides of iron, manganese, zinc, or other material or combination of materials. Alternately, they can be formed of a material having a low magnetic permeability, such as copper, aluminum, or other material. 
     In these and other embodiments of the present invention, portions of the attachment devices can be nonconductive. These nonconductive portions, such as an enclosure for the attachment portion, stalk, a contacting surface, and other nonconductive portions, can be formed using injection or other molding, 3-D printing, machining, or other manufacturing process. They can be formed of silicon or silicone, rubber, hard rubber, plastic, nylon, liquid-crystal polymers (LCPs), or other nonconductive material or combination of materials. The boards can be formed of FR-4 or other material. 
     These and other embodiments of the present invention can provide attachment devices that can be used to secure various types of devices, such as portable computing devices, tablet computers, desktop computers, laptop computers, all-in-one computers, cell phones, wearable-computing devices, storage devices, portable media players, navigation systems, monitors, power supplies, adapters, remote control devices, audio devices, chargers, and other devices in place in a vehicle or other conveyance, such as a train or plane, or other fixed or mobile location. 
     While embodiments of the present invention are well-suited to providing attachment device between phones and vehicles, they can be used in other types of applications as well. For example, embodiments of the present invention can provide attachment devices that can be used between tablet computers and vehicles, or between phones or tablets and other structures. 
     Various embodiments of the present invention can incorporate one or more of these and the other features described herein. A better understanding of the nature and advantages of the present invention can be gained by reference to the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an attachment device according to an embodiment of the present invention; 
         FIG.  2    is a partially exploded view of the attachment device of  FIG.  1   ; 
         FIG.  3    is an exploded view of the attachment device of  FIG.  1   ; 
         FIG.  4    illustrates a cutaway side view of the attachment device of  FIG.  1   ; 
         FIG.  5    illustrates a portion of an attachment device according to an embodiment of the present invention; 
         FIG.  6    illustrates an underside of the portion of the attachment device shown in  FIG.  5   ; 
         FIG.  7    is an exploded diagram of the portion of an attachment device of  FIG.  5   ; 
         FIGS.  8 A and  8 B  are side views of magnets that can be used in the attachment device of  FIG.  1    or in other attachment devices according to embodiments of the present invention; 
         FIG.  9    illustrates another attachment device according to an embodiment of the present invention; 
         FIG.  10    illustrates a back side of the attachment device of  FIG.  9   ; 
         FIG.  11    is an exploded view of a module for the attachment device of  FIG.  10   ; 
         FIG.  12    is an exploded view of another module for an attachment device according to an embodiment of the present invention; 
         FIG.  13    shows a simplified representation of a wireless charging system incorporating a magnetic alignment system according to some embodiments; 
         FIG.  14 A  shows a perspective view of a magnetic alignment system according to some embodiments, and  FIG.  14 B  shows a cross-section through the magnetic alignment system of  FIG.  14 A ; 
         FIG.  15 A  shows a perspective view of a magnetic alignment system according to some embodiments, and  FIG.  15 B  shows a cross-section through the magnetic alignment system of  FIG.  15 A ; 
         FIG.  16    shows a simplified top-down view of a secondary alignment component according to some embodiments; 
         FIG.  17 A  shows a perspective view of a magnetic alignment system according to some embodiments, and  FIG.  17 B  shows an axial cross-section view through a portion of the system of  FIG.  17 A , while  FIGS.  17 C through  17 E  show examples of arcuate magnets with radial magnetic orientation according to some embodiments; 
         FIGS.  18 A and  18 B  show graphs of force profiles for different magnetic alignment systems, according to some embodiments; 
         FIG.  19    shows a simplified top-down view of a secondary alignment component according to some embodiments; 
         FIG.  20 A  shows a perspective view of a magnetic alignment system according to some embodiments, and  FIGS.  20 B and  20 C  show axial cross-section views through different portions of the system of  FIG.  20 A ; 
         FIGS.  21 A and  21 B  show simplified top-down views of secondary alignment components according to various embodiments; 
         FIG.  22    shows a simplified top-down view of a secondary alignment component according to some embodiments; 
         FIG.  23    shows an example of a magnetic alignment system with an annular alignment component and a rotational alignment component according to some embodiments; 
         FIGS.  24 A and  24 B  show an example of rotational alignment according to some embodiments; 
         FIGS.  25 A and  25 B  show a perspective view and a top view of a rotational alignment component having a “z-pole” configuration according to some embodiments; 
         FIGS.  26 A and  26 B  show a perspective view and a top view of a rotational alignment component having a “quad pole” configuration according to some embodiments; 
         FIGS.  27 A and  27 B  show a perspective view and a top view of a rotational alignment component having an “annulus design” configuration according to some embodiments; 
         FIGS.  28 A and  28 B  show a perspective view and a top view of a rotational alignment component having a “triple pole” configuration according to some embodiments; 
         FIG.  29    shows graphs of torque as a function of angular rotation for magnetic alignment systems having rotational alignment components according to various embodiments; 
         FIG.  30    shows a portable electronic device having an alignment system with multiple rotational alignment components according to some embodiments; 
         FIGS.  31 A through  31 C  illustrate moving magnets according to an embodiment of the present invention; 
         FIGS.  32 A and  32 B  illustrate a moving magnetic structure according to an embodiment of the present invention; 
         FIGS.  33 A and  33 B  illustrate a moving magnetic structure according to an embodiment of the present invention; 
         FIG.  34    through  FIG.  36    illustrate a moving magnetic structure according to an embodiment of the present invention; 
         FIG.  37    illustrates a normal force between a first magnet in a first electronic device and a second magnet in a second electronic device; 
         FIG.  38    illustrates a shear force between a first magnet in a first electronic device and a second magnet in a second electronic device; 
         FIGS.  39 A and  39 B  illustrate a moving magnet in conjunction with a high friction surface according to an embodiment of the present invention; 
         FIGS.  40 A and  40 B  illustrate a moving magnet in conjunction with a high friction surface according to an embodiment of the present invention; 
         FIGS.  41 A and  41 B  illustrate a moving magnet in conjunction with a high friction surface according to an embodiment of the present invention; 
         FIGS.  42 A and  42 B  illustrate another moving magnet in conjunction with a high friction surface according to an embodiment of the present invention; 
         FIG.  43    illustrates a cutaway side view of another moving magnet structure according to an embodiment of the present invention; 
         FIG.  44    is a partially transparent view of the moving magnet structure of  FIG.  43   ; 
         FIG.  45    is another cutaway side view of the electronic device of  FIG.  43   ; 
         FIGS.  46  and  47    illustrate the electronic device of  FIG.  43    as it engages with a second electronic device; 
         FIGS.  48 A and  48 B  illustrate structures for constraining motions of magnets in an electronic device according to an embodiment of the present invention; 
         FIGS.  49 A and  49 B  illustrate structures for constraining motions of magnets in an electronic device according to an embodiment of the present invention; 
         FIGS.  50 A and  50 B  illustrate structures for constraining motions of magnets an electronic device according to an embodiment of the present invention; 
         FIG.  51    shows an exploded view of a wireless charger device incorporating an NFC tag circuit according to some embodiments; 
         FIG.  52    shows a partial cross-section view of a wireless charger device according to some embodiments; 
         FIG.  53    shows a flow diagram of a process that can be implemented in a portable electronic device according to some embodiments; and 
         FIG.  54    is a block diagram illustrating an electronic system including an electronic device and an attachment device according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
       FIG.  1    illustrates an attachment device for securing a phone or other electronic device to a vehicle or other conveyance or location according to an embodiment of the present invention. This figure, as with the other figures, is shown for illustrative purposes and does not limit either the embodiments of the present invention or the claims. 
     Attachment device  100  can be used to secure an electronic device  290  (shown in  FIG.  8 B ) to a surface or structure, such as a surface or structure in a vehicle (not shown.) In this particular example, electronic device  290  can be a phone, though electronic device  290  can instead be a tablet computer, wearable computing device, camera, or other electronic, mechanical, or electromechanical device. 
     In these and other embodiments of the present invention, attachment device  100  (and the other attachment devices shown herein) can be a passive attachment device to mechanically secure electronic device  290  to a surface or structure. In these and other embodiments the present invention, attachment device  100  (and the other attachment devices shown herein including attachment devices  300  and  500 ) can instead be a powered attachment device. When attachment device  100  is a powered attachment device, attachment device  100  can include a connector receptacle  340  (shown in  FIG.  10   ) to accept a connector insert  910  of a cable  900  (shown in  FIG.  10   ) where power is received over cable  900 . Alternatively, the cable can be tethered or connected directly to components inside attachment device  100 . A battery (not shown) in attachment device  100  can be wirelessly charged, for example by placing contacting surface  110  on a surface of a wireless charger. A power converter (not shown) can further be included in attachment device  100 , or it can be separate and attached to a surface or structure of a vehicle, or elsewhere. This power converter can receive a first voltage, such as a voltage from a car battery, and convert the received voltage to a second voltage that can be provided to control circuitry such as control circuitry  440  (shown in  FIG.  11   ) in attachment device  100  or other attachment device. 
     Attachment device  100  can include front enclosure  120  covered completely or partially by contacting surface  110 . Contacting surface  110  can physically contact a backside of a phone or other electronic device  290  such that a screen (not shown) on a front side of electronic device  290  can be viewed. Contacting surface  110  can be a high friction or high stiction surface that increases a shear force needed to remove electronic device  290  from attachment device  100 . Contacting surface  110  can also be at least somewhat adhesive. This can increase a normal force needed to remove electronic device  290  from attachment device  100 . Contacting surface  110  can be formed of an elastomer, plastic, PVC plastic, rubber, silicon rubber, polycarbonate (PC), urethane, polyurethane, nitrile, neoprene, silicone, or other material or combination of materials. For example, contacting surface  110  can be formed of PC covered in a high-friction or high-stiction material, which again can be urethane, polyurethane, or other material. 
     Contacting surface  110  can include regions  114  and  116 , which can be thinned regions of contacting surface  110 . Magnet array  210  and alignment magnet  212  (shown in  FIG.  7   ) can be placed behind regions  114  and  116 , respectively. Regions  114  and  116  can optionally be thinned to provide areas on contacting surface  110  that allow an increased magnetic flux at the surface of attachment device  100 . Also, one or more region  112 , region  114 , and region  116  can move relative to the remaining portions of contacting surface  110 , as shown below in  FIG.  39    through  FIG.  47   . 
     It can be desirable for attachment device  100  to provide a strong magnetic force to hold electronic device  290  securely in place to avoid an inadvertent disconnection. However, when no electronic device is mated with attachment device  100 , magnet array  210  can cause undesirable effects. For example, if excessive, the magnetic field provided by magnet array  210  can inadvertently demagnetize stored information, such as information stored on credit cards or transit passes. Accordingly, a magnetic field provided by magnet array  210  can be reduced when an electronic device is not attached and increased when attachment device  100  is, or is about to be, mated with electronic device  290 . This increase can allow for use of a limited magnetic flux provided by attachment device  100  when no phone is attached while allowing an increased magnetic flux for a more secure connection when a phone is attached. 
     This magnetic field can be increased in various ways to more securely attach electronic device  290  to attachment device  100 , while also limiting or reducing a magnetic field when no phone or electronic device  290  is attached. For example, the magnetic field can be generated by an electromagnet (not shown) used along with, or in place of, magnet array  210 . Current through the electromagnet can be increased during mating of attachment device  100  with electronic device  290  to increase the magnetic attraction between attachment device  100  and a phone or other electronic device  290 . Also or instead, magnet array  210  can move from a first position to a second position when attachment device  100  is, or is about to be, mated with electronic device  290 . Examples of magnet arrays that either move or are fixed (nonmoving) and that can be used as magnet array  210 , magnet array  410  (shown in  FIG.  11   ), and magnet array  610  (shown in  FIG.  12   ) are shown below at least in  FIG.  8 A ,  FIG.  8 B , and  FIG.  13    through  FIG.  50 B . 
     Attachment device  100  can include various alignment features where the alignment features help to align electronic device  290  with attachment device  100 . These alignment features can include markings, guides, raised features, or other identifying or mechanical features. Magnet array  210 , whether formed of fixed or moving magnets, or other magnets, can be used as such an alignment feature. 
     In some circumstances, it can be desirable for electronic device  290  to align to attachment device  100  in a specific orientation, such as a portrait or landscape orientation. Accordingly, attachment device  100 , and other attachment devices included in these and other embodiments of the present invention, can include one or more alignment features to align electronic device  290  in a specific orientation. For example, attachment device  100  can include various markings, guides, steps, or other features. Attachment device  100  can include one or more alignment magnets  212 , as shown in  FIG.  7   . Alignment magnet  212  can be positioned under region  116  on contacting surface  110  elsewhere in or on attachment device  100 . Alignment magnet  212  can be attracted to a corresponding magnet in electronic device  290  and can help to align electronic device  290  in a specific orientation, such as in a portrait or landscape orientation. Alignment magnet  212  can be a fixed or moving magnet. Further examples and details of alignment magnets that can be used as alignment magnet  212  (and the other alignment magnets shown here, such as alignment magnet  412  (shown in  FIG.  11   ) and alignment magnet  612  (shown in  FIG.  12   ), are shown below in  FIG.  23    through  FIG.  30   . 
     Attachment device  100  can further include stalk  130 . Stalk  130  can terminate in grip  140 , which can include slots  142 . Grip  140  and slots  142  can allow attachment device  100  to attach to a surface or other structure in a vehicle or elsewhere. Stalk  130  can include a ball joint or other feature that can allow contacting surface  110 , and therefore a screen of electronic device  290 , to tilt and rotate to different angles to facilitate viewing. 
       FIG.  2    is a partially exploded view of the attachment device of  FIG.  1   . In this example, attachment device  100  can include back plate  170 . Back plate  170  and contacting surface  110  (shown in  FIG.  1   ) can form an enclosure for a magnet array  210  and alignment magnet  212  (both shown in  FIG.  7   ) and other components, such as coil  630  and near-field communication components  650  as shown in  FIG.  12   . As such, back plate  170 , contacting surface  110 , magnet array  210 , and the other components, can form a module for attachment device  100 . Stalk  130  can be attached to mid-plate  150 , which can in turn be attached to back plate  170  with fasteners  154 . Front enclosure  120  can then be attached to mid-plate  150  to cover mid-plate  150  and back plate  170 . Side edges  121  of front enclosure  120  can cover side edges  151  of mid-plate  150  to reduce a number of visible seams on attachment device  100 . Front enclosure  120  can include opening  122  for stalk  130  and grip  140 . Grip  140  can include slots  142 . 
     In this example, contacting surface  110  can be formed of a silicone layer. The silicone layer can be formed over a more rigid layer, for example a layer formed of polycarbonate. Contacting surface  110  can be formed using a one or two shot injection-molding process. Mid-plate  150 , front enclosure  120 , and back plate  170  can be formed of metal, such as aluminum, stainless steel, or other material. Mid-plate  150 , front enclosure  120 , and back plate  170  can be stamped, machined, formed by metal-injection molding, 3-D printing, or other technique. Mid-plate  150 , front enclosure  120 , back plate  170 , and the portions of stalk  130  can be formed of plastic or other material. Mid-plate  150 , front enclosure  120 , back plate  170 , and the portions of stalk  130  can be injection molded or formed using other techniques. Slots  142  can be formed of rubber, silicone, or other material that can help to secure attachment device  100  in place in a vehicle or other structure. 
     Back plate  170  and contacting surface  110  can enclose a magnet array  210 . This magnet array  210  can attract corresponding magnets (shown as corresponding magnet array  292  in  FIG.  8 B , and shown as secondary alignment components  1318  in  FIG.  13   ) in electronic device  290  (shown in  FIG.  8 B , and which can be represented by electronic device  1304  in  FIG.  13   .) This magnetic attraction can secure electronic device  290  to attachment device  100  in a direction normal to, or orthogonal to, contacting surface  110 . The magnetic connection between electronic device  290  and attachment device  100  can provide a fast and simple way of attaching a phone or other electronic device  290  to a vehicular surface or structure. 
     It can be desirable that contacting surface  110  be adjustable relative to grip  140 . This can allow a screen (not shown) of electronic device  290  attached to contacting surface  110  to be rotated and tilted relative to a surface or structure that grip  140  is attached to. Accordingly, stalk  130  can include one or more ball-joints or other flexible joints to allow this adjustment. An example is shown below. 
       FIG.  3    is an exploded view of the attachment device of  FIG.  1   . Attachment device  100  can include contacting surface  110  that can be mated with back plate  170 . Back plate  170  can be joined to mid-plate  150  by adhesive or insulating layer  172 . Mid-plate  150  can be further attached to back plate  170  with fasteners  154  and washers  153 . Fastener  156  can pass through opening  152  in mid-plate  150  and attach to spherical joint portion  184  of stalk  130 . A ball joint formed by spherical joint portion  184  and cylindrical joint portion  180  can be included. Spherical joint portion  184  can be held in place in cylindrical joint portion  180 . Cylindrical joint portion  180  can rotate and tilt relative to spherical joint portion  184  to allow for the adjustment of a position of a screen of electronic device  290  (shown in  FIG.  8 A ) attached to contacting surface  110 . Grip  140  can be attached to plate  188 . Plate  188  can be attached to alignment feature  186 . Alignment feature  186  can be attached using fasteners  183  to cylindrical joint portion  180 . Cover  182  can be attached to alignment feature  186 . Opening  122  in front enclosure  120  can provide a passage for grip  140 . Front enclosure  120  can be formed of plastic or other material and can cover mid-plate  150  for cosmetic or other purposes. 
       FIG.  4    illustrates a cutaway side view of the attachment device of  FIG.  1   . Attachment device  100  can include contacting surface  110  that can form an enclosure with back plate  170 . Mid-plate  150  can be attached to back plate  170 . Fastener  156  can attach mid-plate  150  to spherical joint portion  184  of stalk  130 . Spherical joint portion  184  can be held in place in cylindrical joint portion  180 . Cylindrical joint portion  180  can rotate and tilt relative to spherical joint portion  184  to allow for the adjustment of a position of a screen (not shown) of electronic device  290  attached to contacting surface  110 . Alignment feature  186  can be attached to cylindrical joint portion  180  using fasteners  183 . Plate  188  can attach alignment feature  186  to grip  140 . Front enclosure  120  can cover a rear surface of mid-plate  150  for cosmetic or other reasons. 
       FIG.  5    illustrates a portion of an attachment device according to an embodiment of the present invention. This portion, which can be referred to as a module, can include contacting surface  110  and back plate  170 , where contacting surface  110  and back plate  170  form an enclosure. Region  116  and region  114 , which can be thinned, can be located over magnet array  210  and alignment magnets  212  (shown in  FIG.  7   ), respectively. Thinned region  114  can define interior region  112 . Region  114  or region  112 , or both, can move relative to the other portions of contacting surface  110 , as shown in  FIG.  39    through  FIG.  47    below. 
     Contacting surface  110  and back plate  170  can provide an enclosure housing magnet array  210 , alignment magnets  212 , and other components as shown herein to form a module. The resulting module can be used to form attachment device  100  by attaching mid-plate  150 , stalk  130 , and front enclosure  120  (all shown in  FIG.  2   .) The resulting module or similar modules can also be used to form other attachment devices, such as the attachment device  300  shown in  FIG.  9   . 
       FIG.  6    illustrates an underside of the portion of the attachment device shown in  FIG.  5   . Mid-plate  150  (shown in  FIG.  4   ) can be secured to back plate  170  using fasteners  154  (shown in  FIG.  3   ), which can be screwed into threaded portions  159 . 
     Back plate  170  and contacting surface  110  can house magnet array  210  (shown in  FIG.  7   .) Magnet array  210  can be fixed in place relative to back plate  170 . Alternatively, magnet array  210  can move between at least a first position and a second position. For example, when attachment device is not mated with an electronic device, magnet array  210  can be in the first position away from contacting surface  110 . This can reduce a stray magnetic field at contacting surface  110 , which can help to protect magnetically stored information. As electronic device  290  (shown in  FIG.  8 B ) is brought into proximity to attachment device  100 , corresponding magnets or magnet array  292  (shown in  FIG.  8 A  and also shown as secondary alignment components  1318  in  FIG.  13   ) in electronic device  290  can attract magnet array  210  in attachment device  100 . This attraction can cause the movement of magnet array  210  in attachment device  100  to the second position, which can be closer to contacting surface  110 . This change in position can increase the magnetic field between magnet array  210  and corresponding magnets or magnet array  292  in electronic device  290 , thereby securing electronic device  290  in place against contacting surface  110  of attachment device  100 . Examples of magnet arrays that are fixed as well as examples of magnet arrays that are capable of moving are shown below in  FIG.  8 A ,  FIG.  8 B , and  FIG.  13    through  FIG.  50 B . 
       FIG.  7    is an exploded diagram of the portion of an attachment device of  FIG.  5   . Contacting surface  110  and back plate  170  can form an enclosure supporting magnet array  210  and alignment magnet  212 . Magnet array  210  and alignment magnet  212  can be supported by shield  220  and shield  222 , respectively. Return plate  230  can be attached to back plate  170 . Adhesive layers  240  and  250  can attach back plate  170  to contacting surface  110 . Adhesive layer  240  can be a narrow strip or bead that secures an outside edge of contacting surface  110  to back plate  170 . Magnet array  210  and shield  220  can move relative to return plate  230  as shown in the following figures. Additionally, other examples that can be used for these components are shown below. For example, the fixed and moving magnets of  FIGS.  13  through  50 B  can be used as magnet array  210  and the other magnet arrays and alignment magnets in these examples. 
     In these and other embodiments of the present invention, these structures can be formed of various materials in various ways. Contacting surface  110 , contacting surface  310  (shown in  FIG.  11   ), or contacting surface  510  (shown in  FIG.  12   ), and the other contacting surfaces shown here or otherwise utilized by an embodiment of the present invention, can be formed of an elastomer, plastic, PVC plastic, rubber, silicon rubber, urethane, polyurethane, nitrile, polycarbonate (PC), neoprene, silicone, or other material. For example, they can be formed of a layer of elastomer, plastic, PVC plastic, rubber, silicon rubber, urethane, polyurethane, nitrile, polycarbonate (PC), neoprene, silicone, or other material over a layer of PC. Back plate  170 , mid-plate  150  (shown in  FIG.  2   ), front enclosure  120  (shown in  FIG.  2   ), and the other enclosures, plates, and other enclosure portions, shown here or otherwise utilized by an embodiment of the present invention, can be formed of a metal, such as stainless steel or aluminum, plastic, nylon, or other conductive or nonconductive material. They can be formed using computer numerical control (CNC) or other type of machining, stamping, metal injection molding (MIM), or other technique. Return plate  230 , shield  220 , and shield  222 , can be formed of materials having a high magnetic permeability, such as stainless steel, ferritic stainless steel, oxides of iron, manganese, zinc, or other material or combination of materials. Adhesive layers  240  and  250  can be a pressure-sensitive adhesive, a heat-activated film, or other type of adhesive. 
       FIGS.  8 A and  8 B  are cross-sections of magnets that can be used in the attachment device of  FIG.  1    or in other attachment devices according to embodiments of the present invention. These cross-sections are taken along cut-line A-B shown in  FIG.  5   . In  FIG.  8 A , alignment magnet  212  can be attached to shield  222  in attachment device  100 . Magnet array  210  can be attached to shield  220 . Shield  220  can be magnetically attached to return plate  230 . In this configuration, magnetic flux provided at contacting surface  110  by magnet array  210  can be minimized by the position of magnet array  210  away from contacting surface  110 . This minimization can help to protect magnetically stored information that might encounter contacting surface  110 . Magnet array  210  and alignment magnet  212  can be housed by contacting surface  110  and back plate  170 . Contacting surface  110  can include thinned regions  114  and  116 , as well as region  112 . 
     In  FIG.  8 B , corresponding magnet or magnet array  292  of electronic device  290  can attract magnet array  210  and shield  220  in attachment device  100 . Shield  220  can separate from return plate  230 . Magnet array  210  and shield  220  can move closer to a top surface of contacting surface  110 . In this configuration, magnetic flux provided at contacting surface  110  by magnet array  210  can be increased by the position of magnet array  210  being closer to contacting surface  110 . This can help to secure electronic device  290  to contacting surface  110  of attachment device  100 . Again, alignment magnet  212  can be attached to shield  222 , and shield  222  and return plate  230  can be attached to back plate  170 . 
     An electronic device can often operate in a high power consumption mode when it is attached to an attachment device according to an embodiment of the present invention. For example, the electronic device can provide music or navigation instructions. These and other activities can consume a fair amount of power from a battery internal to the electronic device. Accordingly, in these and other embodiments of the present invention, it can be desirable for an attachment device to be able to charge the electronic device. Examples of attachment devices that can charge electronic devices are shown in the following figures. 
       FIG.  9    illustrates another attachment device according to an embodiment of the present invention. Attachment device  300  can include contacting surface  310 , front enclosure  320 , and grip  330 . Grip  330  can include slots  332  to allow grip  330  to attach to a surface or structure in a vehicle or elsewhere. Power and data can be received by attachment device  300  through cable  900 . Cable  900  can include connector insert  910  that can plug into connector receptacle  340  in attachment device  300 . Alternatively, cable  900  can be directly tethered to internal components or circuitry of attachment device  300 . Data can be received or provided by an external device through cable  900  as well. Alternatively, attachment device  300  (or attachment device  500  below, or other attachment device) can include a battery for power, where the battery is charged over cable  900  or wirelessly, for example by placing contacting surface  310  on a surface of a wireless charger. 
     Connector receptacle  340  can be a universal serial bus (USB) connector, such as a USB Type-C connector, a Lightning™ connector, or other type of connector. Connector receptacle  340  can accept corresponding connector insert  910  of cable  900  through which power and data can be received by attachment device  300  and data can be provided by attachment device  300 . 
     Contacting surface  310  can physically contact electronic device  290  (shown in  FIG.  8 B .) For example, a backside of electronic device  290  can contact contacting surface  310  of attachment device  300  such that a screen (not shown) of electronic device  290  is visible. Contacting surface  310  can be a high friction or high stiction surface that increases a shear force needed to remove electronic device  290  from attachment device  300 . Contacting surface  310  can also be at least somewhat adhesive. This can increase both a normal force and a shear force needed to remove electronic device  290  from attachment device  300 . Contacting surface  310  can be formed of an elastomer, plastic, PVC plastic, rubber, silicon rubber, urethane, polyurethane, nitrile, neoprene, silicone, or other material. Contacting surface  310  can be relatively plain as shown, or can include features such as region  112 , region  114 , or region  116  as with contacting surface  110  (shown in  FIG.  1   .) 
       FIG.  10    illustrates a back side of the attachment device of  FIG.  9   . Attachment device  300  can include grip  330  having slots  332 . Attachment device  300  can include contacting surface  310 , back plate  370 , and front enclosure  320 . Back plate  370  and contacting surface  310  can form an enclosure to house electrical and magnetic components as shown in the following figure. Electrical access to these components, more specifically to contacts on a back side of control circuitry  440  (shown in  FIG.  11   ) can be gained through connector  372  or cable  900 . Connector  372  can be used for testing and programming and might not otherwise be directly accessible during use but can instead be protected by front enclosure  320 . Cable  900  can be a tethered cable, or it can connect to attachment device  300  by plugging connector insert  910  into connector receptacle  340 . 
     In this example, back plate  370  and contacting surface  310  can form an enclosure to house electrical and magnetic components as a module as shown in the following figure. Front enclosure  320  and grip  330  can be formed on a surface of back plate  370  by insert molding or other process. Front enclosure  320  and grip  330  can be formed separately or together in a single molding or other process. 
       FIG.  11    is an exploded view of a module for the attachment device of  FIG.  10   . Attachment device  300  can include an enclosure formed by contacting surface  310  and back plate  370 . Magnet array  410  and alignment magnet  412  can be attached to shield  420  and shield  422 , respectively. Coil  430  can include leads  432  that can be attached to control circuitry  440 . Control circuitry  440  can control charging currents provided to coil  430  through leads  432 . Return plate  450  can include nonconductive portion  452  to protect leads  432 . Similarly, magnet array  410  and shield  420  can include opening  414  for leads  432 . Back plate  370  can be attached to contacting surface  310  to form an enclosure for a module including magnet array  410 , alignment magnet  412 , shield  420 , coil  430 , control circuitry  440 , and return plate  450 . Coil ferrite  438  can magnetically isolate inductive coil  430  from magnet array  410  and to improve inductive coupling between the coil  430  and a corresponding coil (not shown) of a power receiving phone or electronic device  290  (shown in  FIG.  8 B .) One or more e-shields (not shown) can be included, for example between coil  430  and contacting surface  310 , and can be formed of a layer of copper or other conductive material to intercept electric fields between coil  430  and a corresponding coil (not shown) in electronic device  290 , and can have a low magnetic permeability to pass magnetic fields between coil  430  and the corresponding coil. Such an e-shield can include breaks to prevent the formation of eddy currents. 
     In this example, the resulting module can be included in a completed attachment device by including portions such as stalk  130  and front enclosure  120  (shown in  FIG.  2   ), by including portions such as front enclosure  320  and grip  330  (shown in  FIG.  10   ), or by including other portions that can be used to attach the module to a surface of structure in a vehicle or other conveyance or location. 
     These attachment device enclosures can further house near-field communication circuitry and components, such as a near-field communication tag and capacitors. The near-field communication circuitry and components can allow an electronic device to detect the attachment device. This recognition can prompt the electronic device to perform one or more activities. For example, the electronic device can launch one or more applications in response to this recognition. Various software and control features can be implemented in these and other embodiments of the present invention. The software and control features can be implemented in an attachment device, an electronic device attached to the attachment device, or in other devices associated with the electronic device or a vehicle to which the attachment device is attached, by circuitry or components in an area surrounding the attachment device or elsewhere, or by a combination of these. An example of a module for an attachment device that includes near-field communications components is shown in the following figure. 
       FIG.  12    is an exploded view of another module for an attachment device according to an embodiment of the present invention. Attachment device  500  can include an enclosure formed of contacting surface  510  and back plate  570 . Attachment device  500  can further include a stalk or other attachment structure (not shown). For example, attachment device  500  can include stalk  130  or grip  330 , as shown in the above examples. 
     Attachment device  500  can enclose a transmitter including near-field communications components  650 . Near-field communications components  650  can include a tag, capacitor, and support ring. A magnetometer or other sensor (not shown) in an electronic device  290  (shown in  FIG.  8 B ) can sense magnet array  610  in attachment device  500 . In response, electronic device  290  can activate its own internal receiver near-field communications components and circuitry (not shown) to generate a radio-frequency field. Near-field communications components  650  in attachment device  500  can modulate this radio-frequency field to transmit data back to the receiver in electronic device  290 . The modulated radio-frequency field can be read by the near field communications components and circuitry in electronic device  290 . Electronic device  290  can then determine that it is mounted on attachment device  500 . Once this determination is been made, electronic device  290  can enter an appropriate mode. 
     Attachment device  500  can further include contacting surface  510  attached to back plate  570  with adhesive  512 . Contacting surface  510  and back plate  570  can form an enclosure to house magnet array  610  and alignment magnets  612  as a module. Shield  620  and shield  622  can be provided for magnet array  610  and alignment magnet  612 . Shield  620  can be attached to back plate  570  by adhesive  616 . Alignment magnet  612  can be attached to back plate  570  by adhesive  618 . Coil  630  and control circuitry  660  can provide charging currents to electronic device  290 . Coil  630  can be supported by coil ferrite  638 . Coil ferrite  638  and bottom ferrite  640  can provide shielding for coil  630 . Coil ferrite  638  can magnetically isolate inductive coil  630  from magnet array  610  and to improve inductive coupling between the coil  630  and a corresponding coil (not shown) of a power receiving phone or electronic device  290 . Bottom ferrite  640  can be attached to coil  630  with adhesive layer  642  and to back plate  570  with adhesive layer  644 . Control circuitry  660  can be attached to back plate  570  with adhesive  662 . One or more e-shields (not shown) can be included, for example between coil  630  and contacting surface  510 , and can be formed of a layer of copper or other conductive material to intercept electric fields between coil  630  and a corresponding coil (not shown) in electronic device  290  (shown in  FIG.  8 B ), and can have a low magnetic permeability to pass magnetic fields between coil  630  and the corresponding coil. Such an e-shield can include breaks to prevent the formation of eddy currents. 
     In this example, the resulting module can be included in a completed attachment device by including portions such as stalk  130  and front enclosure  120  (shown in  FIG.  2   ), by including portions such as front enclosure  320  and grip  330  (shown in  FIG.  10   ), or by including other portions that can be used to attach the module to a surface of structure in a vehicle or other conveyance or location. 
     These circuits and components can allow attachment devices  100 ,  300 , and  500  to provide power to an attached electronic device, such as electronic device  290  (shown in  FIG.  8 B .) They can also allow attachment devices  100 ,  300 , and  500  to receive data from electronic device  290 . They can also allow attachment devices  100 ,  300 , and  500  to provide data to electronic device  290 . They can also allow the electronic device to detect that the electronic device  290  is attached to an attachment device, such as attachment device  100 ,  300 , or  500 . One or more of these functions can be compatible with various specifications or protocols, such as the Qi wireless charging and data protocol or an NFC standard, such as ISO/IEC 14443, or with other standards or protocols that are currently available or are being developed. 
     For example, power can be received by attachment device  300  (or attachment devices  100  or  500 ) via a cable  900  and provide to an electronic device, such as electronic device  290 . This received power can be an AC voltage that is converted to a DC voltage, or it can be a DC voltage. Control circuitry  440  can provide an alternating current to coil  430 . This current can generate a time-varying magnetic flux that can induce currents in a corresponding coil in electronic device  290 . These induced currents can be used to charge a battery in electronic device  290 . 
     Also, data can be received by attachment device  500  (or attachment devices  100  or  300 ) from an electronic device, such as electronic device  290 . For example, control circuitry (not shown) in electronic device  290  (shown in  FIG.  8 B ) can generate a current in the corresponding coil. This current can be modulated to convey data. The current can be modulated in amplitude, phase, or frequency. The current can induce a current in coil  430 , from which data can be read by control circuitry  440 . The read data can be used by attachment device  300 , or sent to another electronic device via cable  900 . 
     Similarly, data can be provided by attachment device  300  (or attachment devices  100  or  500 ) to the electronic device. Control circuitry  440  can receive data, either from attachment device  300  itself, or from an external source (not shown) via the cable  900 . Control circuitry  440  can modulate a current provided to coil  430 . This current can be modulated in amplitude, phase, or frequency. The current can induce a current in the corresponding coil in the electronic device, from which the data can be read by an electronic device, such as electronic device  290 . 
     The electronic device  290  can detect that the electronic device  290  is attached to an attachment device, such as attachment device  100 ,  300 , or  500 . A magnetometer or other sensor (not shown) in electronic device  290  can sense magnet array  410  in attachment device  500  (as an example.) In response, electronic device  290  can activate a receiver including internal near-field communications components and circuitry (not shown) to generate a radio-frequency field. A transmitter, such as near-field communications components  650  in attachment device  500  (or attachment device  100  or attachment device  300 ) can modulate this radio-frequency field. The modulated radio-frequency field can be read by the near field communications components and circuitry in electronic device  290 . Electronic device  290  can then determine that it is mounted on attachment device  500 . 
     Embodiments of the present invention can provide attachment devices having various combinations of the components and features described herein. For example, an attachment device, such as attachment device  100  (shown in  FIG.  1   , or attachment device  300  or attachment device  500 ), can include a magnet array, such as magnet array  210 . This attachment device can further include an alignment magnet, such as alignment magnet  212 . A coil and electronics, such as coil,  430  and control circuitry  440 , can be included in an alignment device, such as attachment device  300  (shown in  FIG.  11   .) Near-field communication circuitry, such as near-field communication components  650 , can be included as well, either with or without a coil and circuitry, such as coil  630  and control circuitry  660  in an attachment device, such as attachment device  500  (shown in  FIG.  12   , (or attachment device  100  or attachment device  300 ).) 
     While a phone or electronic device is not shown in many of the examples, such a phone or electronic device is partially explained in the context of electronic device  290  (shown in  FIG.  8 B ), electronic device  1304  (shown in  FIG.  13   ), electronic device  5414  (shown in  FIG.  54   ) and the other electronic devices shown herein. 
     In these and other embodiments of the present invention, these structures can be formed of various materials in various ways. Some or all of each contacting surface  110 ,  310 ,  510 , or other contacting surface shown here, or otherwise utilized by an embodiment of the present invention, can be formed of an elastomer, plastic, PVC plastic, rubber, silicon rubber, urethane, polyurethane, nitrile, polycarbonate, neoprene, silicone, or other material. The plates, such as mid-plate  150 , back plate  170 , front enclosure  120 , and other enclosure and housing portions, shown here or otherwise utilized by an embodiment of the present invention, can be formed of a metal, such as stainless steel or aluminum, plastic, nylon, or other conductive or nonconductive material, such as a plastic. They can be formed using computer numerical control (CNC) or other type of machining, stamping, metal injection molding (MIM), or other technique. Coil ferrite  438 , coil ferrite  638 , bottom ferrite  640 , and other ferritic portions incorporated by embodiments of the present invention can be formed of a material that has high magnetic permeability, such as stainless steel, ferritic stainless steel, oxides of iron, manganese, zinc, or other material or combination of materials. One or more e-shields (not shown) can be included, and can be formed of a layer of copper or other conductive material to intercept electric fields between a coil, such as coil  430  or coil  630 , in an attachment device and a corresponding coil (not shown) in an electronic device, such as electronic device  290  (shown in  FIG.  8 B ), and can have a low magnetic permeability to pass magnetic fields between coil  430  or coil  630  and the corresponding coil. An e-shield can include breaks to prevent the formation of eddy currents. The control circuits, such a control circuitry  440  or control circuitry  660 , can be located on boards that can be formed of FR-4 or other material. Adhesive layers used here can be formed of a pressure-sensitive adhesive, a heat-activated film, or other type of adhesive. 
     In these and other embodiments of the present invention, portions of the attachment devices can be conductive. These conductive portions, such as shields, return plates, backplates, and other portions can be formed using stamping, forging, metal-injection molding, 3-D printing, CNC or other machining, or other manufacturing process. They can be formed of a material that has high magnetic permeability, such as stainless steel, ferritic stainless steel, oxides of iron, manganese, zinc, or other material or combination of materials. Alternately, the can be formed of a material having a low magnetic permeability, such as copper, aluminum, or other material. 
     In these and other embodiments of the present invention, portions of the attachment devices can be nonconductive. These nonconductive portions, such as an enclosure for the attachment portion, stalk, a contacting surface, and other nonconductive portions, can be formed using injection or other molding, 3-D printing, machining, or other manufacturing process. They can be formed of silicon or silicone, rubber, hard rubber, plastic, nylon, liquid-crystal polymers (LCPs), or other nonconductive material or combination of materials. The boards can be formed of FR-4 or other material. 
     These and other embodiments of the present invention can provide attachment devices that can be used to secure various types of devices, such as portable computing devices, tablet computers, desktop computers, laptop computers, all-in-one computers, cell phones, wearable-computing devices, storage devices, portable media players, navigation systems, monitors, power supplies, adapters, remote control devices, audio devices, chargers, and other devices in place in a vehicle or other conveyance, such as a train or plane, or other fixed or mobile location. 
     While embodiments of the present invention are well-suited to providing attachment device between phones and vehicles, they can be used in other types of applications as well. For example, embodiments of the present invention can provide attachment devices that can be used between tablet computers and vehicles, or between phones or tablets and other structures. 
     Described herein are various embodiments of magnetic alignment systems and components thereof. The magnetic alignment systems shown below can be used as magnet array  210  and alignment magnet  212 , as magnet array  410  and alignment magnet  412 , and as magnet array  610  and alignment magnet  612 , or as other magnet arrays and alignment magnets in other embodiments of the present invention. A magnetic alignment system can include annular alignment components comprising a ring of magnets having a particular magnetic orientation or pattern of magnetic orientations such that a “primary” annular alignment component can attract and hold a complementary “secondary” annular alignment component. In some embodiments described below, the primary annular alignment component is assumed to be in an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), which can be wireless charging device, and which might or might not surround an inductive charging coil, while the secondary annular alignment component is assumed to be in a portable electronic device, which might or might not surround a receiver coil that can receive power from the inductive charging coil of the wireless charging device. Many variations are possible; for instance, a “primary” annular alignment component can be in a portable electronic device while a “secondary” annular alignment component can be in an attachment device, which can be wireless charging device. Also possible are “auxiliary” annular alignment components that are complementary to the primary and secondary annular alignment components such that one surface of the auxiliary annular alignment component is attracted to the primary alignment component while the opposite surface is attracted to the secondary alignment component. An auxiliary annular alignment component can be disposed, e.g., in a case for a portable electronic device. 
     In some embodiments, a magnetic alignment system can also include a rotational alignment component that facilitates aligning two devices in a preferred rotational orientation. It should be understood that any device that has an annular alignment component might or might not also have a rotational alignment component. 
     In some embodiments, a magnetic alignment system can also include an near-field communication (NFC) coil and supporting circuitry to allow devices to identify themselves to each other using an NFC protocol. NFC coils can be disposed inboard of the annular alignment component or outboard of the annular alignment component. It should be understood that an NFC component is optional in the context of providing magnetic alignment. 
       FIG.  13    shows a simplified representation of a wireless charging system  1300  incorporating a magnetic alignment system  1306  according to some embodiments. A portable electronic device  1304  is positioned on a charging surface  1308  of a wireless charging device  1302 . Portable electronic device  1304  can be a consumer electronic device, such as a smart phone, tablet, wearable device, or the like, or any other electronic device for which wireless charging is desired. Wireless charging device  1302  can be any device that is configured to generate time-varying magnetic flux to induce a current in a suitably configured receiving device. For instance, wireless charging device  1302  can be an attachment device, such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device consistent with an embodiment of the present invention, wireless charging mat, puck, docking station, or the like. Wireless charging device  1302  can include or have access to a power source such as battery power or standard AC power. 
     To enable wireless power transfer, portable electronic device  1304  and wireless charging device  1302  can include inductive coils  1310  and  1312 , respectively, which can operate to transfer power between them. For example, inductive coil  1312  can be a transmitter coil that generates a time-varying magnetic flux  1314 , and inductive coil  1310  can be a receiver coil in which an electric current is induced in response to time-varying magnetic flux  1314 . The received electric current can be used to charge a battery of portable electronic device  1304 , to provide operating power to a component of portable electronic device  1304 , and/or for other purposes as desired. (“Wireless power transfer” and “inductive power transfer,” as used herein, refer generally to the process of generating a time-varying magnetic field in a conductive coil of a first device that induces an electric current in a conductive coil of a second device.) 
     To enable efficient wireless power transfer, it is desirable to align inductive coils  1312  and  1310 . According to some embodiments, magnetic alignment system  1306  can provide such alignment. In the example shown in  FIG.  13   , magnetic alignment system  1306  includes a primary magnetic alignment component  1316  disposed within or on a surface of wireless charging device  1302  and a secondary magnetic alignment component  1318  disposed within or on a surface of portable electronic device  1304 . Primary alignment components  1316  and secondary alignment components  1318  are configured to magnetically attract one another into an aligned position in which inductive coils  1310  and  1312  are aligned with one another to effectuate wireless power transfer. 
     According to embodiments described herein, a magnetic alignment component (including a primary or secondary alignment component) of a magnetic alignment system can be formed of arcuate magnets arranged in an annular configuration. In some embodiments, each magnet can have its magnetic polarity oriented in a desired direction so that magnetic attraction between the primary and secondary magnetic alignment components provides a desired alignment. In some embodiments, an arcuate magnet can include a first magnetic region with magnetic polarity oriented in a first direction and a second magnetic region with magnetic polarity oriented in a second direction different from (e.g., opposite to) the first direction. As will be described, different configurations can provide different degrees of magnetic field leakage. 
     In this example, portable electronic device  1304  can be a phone or other electronic device. Wireless charging device  1302  can be an attachment device such as attachment device  100 , attachment device  300 , or attachment device  500 . Primary alignment components  1316  can be used as magnet array  210 , magnet array  410 , magnet array  610 , or as a magnet array in other embodiments of the present invention. Charging surface  1308  can be used as contacting surface  110 , contacting surface  310 , or contacting surface  510 . Inductive coil  1312  can be optional where wireless charging device  1302  is used as an attachment device such as attachment device  100 . Inductive coil  1312  can be used as coil  430 , coil  630 , or other coil in these and other embodiments of the present invention. 
       FIG.  14 A  shows a perspective view of a magnetic alignment system  1400  according to some embodiments, and  FIG.  14 B  shows a cross-section through magnetic alignment system  1400  across the cut plane indicated in  FIG.  14 A . Magnetic alignment system  1400  can be an implementation of magnetic alignment system  1306  of  FIG.  13   . In magnetic alignment system  1400 , the alignment components all have magnetic polarity oriented in the same direction (along the axis of the annular configuration.) For convenience of description, an “axial” direction (also referred to as a “longitudinal” or “z” direction) is defined to be parallel to an axis of rotational symmetry  1401  of magnetic alignment system  1400 , and a transverse plane (also referred to as a “lateral” or “x” or “y” direction) is defined to be normal to axis  1401 . The term “proximal side” is used herein to refer to a side of one alignment component that is oriented toward the other alignment component when the magnetic alignment system is aligned, and the term “distal side” is used to refer to a side opposite the proximal side. 
     As shown in  FIG.  14 A , magnetic alignment system  1400  can include a primary alignment component  1416  (which can be an implementation of primary alignment component  1316  of  FIG.  13   ) and a secondary alignment component  1418  (which can be an implementation of secondary alignment component  1318  of  FIG.  13   ). Primary alignment component  1416  and secondary alignment component  1418  have annular shapes and may also be referred to as “annular” alignment components. The particular dimensions can be chosen as desired. In some embodiments, primary alignment component  1416  and secondary alignment component  1418  can each have an outer diameter of about 174 mm and a radial width of about 6 mm. The outer diameters and radial widths of primary alignment component  1416  and secondary alignment component  1418  need not be exactly equal. For instance, the radial width of secondary alignment component  1418  can be slightly less than the radial width of primary alignment component  1416  and/or the outer diameter of secondary alignment component  1418  can also be slightly less than the radial width of primary alignment component  1416  so that, when in alignment, the inner and outer sides of primary alignment component  1416  extend beyond the corresponding inner and outer sides of secondary alignment component  1418 . Thicknesses (or axial dimensions) of primary alignment component  1416  and secondary alignment component  1418  can also be chosen as desired. In some embodiments, primary alignment component  1416  has a thickness of about 1.5 mm while secondary alignment component  1418  has a thickness of about 0.37 mm. 
     Primary alignment component  1416  can include a number of sectors, each of which can be formed of one or more primary arcuate magnets  1426 , and secondary alignment component  1418  can include a number of sectors, each of which can be formed of one or more secondary arcuate magnets  1428 . In the example shown, the number of primary magnets  1426  is equal to the number of secondary magnets  1428 , and each sector includes exactly one magnet, but this is not required. Primary magnets  1426  and secondary magnets  1428  can have arcuate (or curved) shapes in the transverse plane such that when primary magnets  1426  (or secondary magnets  1428 ) are positioned adjacent to one another end-to-end, primary magnets  1426  (or secondary magnets  1428 ) form an annular structure as shown. In some embodiments, primary magnets  1426  can be in contact with each other at interfaces  1430 , and secondary magnets  1428  can be in contact with each other at interfaces  1432 . Alternatively, small gaps or spaces may separate adjacent primary magnets  1426  or secondary magnets  1428 , providing a greater degree of tolerance during manufacturing. 
     In some embodiments, primary alignment component  1416  can also include an annular shield  1414  disposed on a distal surface of primary magnets  1426 . In some embodiments, shield  1414  can be formed as a single annular piece of material and adhered to primary magnets  1426  to secure primary magnets  1426  into position. Shield  1414  can be formed of a material that has high magnetic permeability, such as stainless steel, and can redirect magnetic fields to prevent them from propagating beyond the distal side of primary alignment component  1416 , thereby protecting sensitive electronic components located beyond the distal side of primary alignment component  1416  from magnetic interference. 
     Primary magnets  1426  and secondary magnets  1428  can be made of a magnetic material such as an NdFeB material, other rare earth magnetic materials, or other materials that can be magnetized to create a persistent magnetic field. Each primary magnet  1426  and each secondary magnet  1428  can have a monolithic structure having a single magnetic region with a magnetic polarity aligned in the axial direction as shown by magnetic polarity indicators  1415 ,  1417  in  FIG.  14 B . For example, each primary magnet  1426  and each secondary magnet  1428  can be a bar magnet that has been ground and shaped into an arcuate structure having an axial magnetic orientation. (As will be apparent, the term “magnetic orientation” refers to the direction of orientation of the magnetic polarity of a magnet.) In the example shown, primary magnet  1426  has its north pole oriented toward the proximal surface and south pole oriented toward the distal surface while secondary magnet  1428  has its south pole oriented toward the proximal surface and north pole oriented toward the distal surface. In other embodiments, the magnetic orientations can be reversed such that primary magnet  1426  has its south pole oriented toward the proximal surface and north pole oriented toward the distal surface while secondary magnet  1428  has its north pole oriented toward the proximal surface and south pole oriented toward the distal surface. 
     As shown in  FIG.  14 B , the axial magnetic orientation of primary magnet  1426  and secondary magnet  1428  can generate magnetic fields  1440  that generate an attractive force between primary magnet  1426  and secondary magnet  1428 , thereby facilitating alignment between respective electronic devices in which primary alignment component  1416  and secondary alignment component  1418  are disposed (e.g., as shown in  FIG.  13   ). While shield  1414  can redirect some of magnetic fields  1440  away from regions below primary magnet  1426 , magnetic fields  1440  may still propagate to regions laterally adjacent to primary magnet  1426  and secondary magnet  1428 . In some embodiments, the lateral propagation of magnetic fields  1440  may result in magnetic field leakage to other magnetically sensitive components. For instance, if an inductive coil having a ferromagnetic shield is placed in the interior region of annular primary alignment component  1416  (or secondary alignment component  1418 ), leakage of magnetic fields may  1440  may saturate the ferrimagnetic shield, which can degrade wireless charging performance. 
     It will be appreciated that magnetic alignment system  1400  is illustrative and that variations and modifications are possible. For instance, while primary alignment component  1416  and secondary alignment component  1418  are each shown as being constructed of eight arcuate magnets, other embodiments may use a different number of magnets, such as sixteen magnets, thirty-six magnets, or any other number of magnets, and the number of primary magnets need not be equal to the number of secondary magnets. In other embodiments, primary alignment component  1416  and/or secondary alignment component  1418  can each be formed of a single, monolithic annular magnet; however, segmenting magnetic alignment components  1416  and  1418  into arcuate magnets may improve manufacturing because smaller arcuate segments are less brittle than a single, monolithic annular magnet and are less prone to yield loss due to physical stresses imposed on the magnetic material during manufacturing. 
     As noted above with reference to  FIG.  14 B , a magnetic alignment system with a single axial magnetic orientation may allow lateral leakage of magnetic fields, which may adversely affect performance of other components of an electronic device. Accordingly, some embodiments provide magnetic alignment systems with reduced magnetic field leakage. Examples will now be described. 
       FIG.  15 A  shows a perspective view of a magnetic alignment system  1500  according to some embodiments, and  FIG.  15 B  shows a cross-section through magnetic alignment system  1500  across the cut plane indicated in  FIG.  15 A . Magnetic alignment system  1500  can be an implementation of magnetic alignment system  1306  of  FIG.  13   . In magnetic alignment system  1500 , the alignment components have magnetic components configured in a “closed loop” configuration as described below. 
     As shown in  FIG.  15 A , magnetic alignment system  1500  can include a primary alignment component  1516  (which can be an implementation of primary alignment component  1316  of  FIG.  13   ) and a secondary alignment component  1518  (which can be an implementation of secondary alignment component  1318  of  FIG.  13   ). Primary alignment component  1516  and secondary alignment component  1518  have annular shapes and may also be referred to as “annular” alignment components. The particular dimensions can be chosen as desired. In some embodiments, primary alignment component  1516  and secondary alignment component  1518  can each have an outer diameter of about 174 mm and a radial width of about 6 mm. The outer diameters and radial widths of primary alignment component  1516  and secondary alignment component  1518  need not be exactly equal. For instance, the radial width of secondary alignment component  1518  can be slightly less than the radial width of primary alignment component  1516  and/or the outer diameter of secondary alignment component  1518  can also be slightly less than the radial width of primary alignment component  1516  so that, when in alignment, the inner and outer sides of primary alignment component  1516  extend beyond the corresponding inner and outer sides of secondary alignment component  1518 . Thicknesses (or axial dimensions) of primary alignment component  1516  and secondary alignment component  1518  can also be chosen as desired. In some embodiments, primary alignment component  1516  has a thickness of about 1.5 mm while secondary alignment component  1518  has a thickness of about 0.37 mm. 
     Primary alignment component  1516  can include a number of sectors, each of which can be formed of a number of primary magnets  1526 , and secondary alignment component  1518  can include a number of sectors, each of which can be formed of a number of secondary magnets  1528 . In the example shown, the number of primary magnets  1526  is equal to the number of secondary magnets  1528 , and each sector includes exactly one magnet, but this is not required; for example, as described below a sector may include multiple magnets. Primary magnets  1526  and secondary magnets  1528  can have arcuate (or curved) shapes in the transverse plane such that when primary magnets  1526  (or secondary magnets  1528 ) are positioned adjacent to one another end-to-end, primary magnets  1526  (or secondary magnets  1528 ) form an annular structure as shown. In some embodiments, primary magnets  1526  can be in contact with each other at interfaces  1530 , and secondary magnets  1528  can be in contact with each other at interfaces  1532 . Alternatively, small gaps or spaces may separate adjacent primary magnets  1526  or secondary magnets  1528 , providing a greater degree of tolerance during manufacturing. 
     In some embodiments, primary alignment component  1516  can also include an annular shield  1514  disposed on a distal surface of primary magnets  1526 . In some embodiments, shield  1514  can be formed as a single annular piece of material and adhered to primary magnets  1526  to secure primary magnets  1526  into position. Shield  1514  can be formed of a material that has high magnetic permeability, such as stainless steel, and can redirect magnetic fields to prevent them from propagating beyond the distal side of primary alignment component  1516 , thereby protecting sensitive electronic components located beyond the distal side of primary alignment component  1516  from magnetic interference. 
     Primary magnets  1526  and secondary magnets  1528  can be made of a magnetic material such as an NdFeB material, other rare earth magnetic materials, or other materials that can be magnetized to create a persistent magnetic field. Each secondary magnet  1528  can have a single magnetic region with a magnetic polarity having a component in the radial direction in the transverse plane (as shown by magnetic polarity indicator  1517  in  FIG.  15 B ). As described below, the magnetic orientation can be in a radial direction with respect to axis  1501  or another direction having a radial component in the transverse plane. Each primary magnet  1526  can include two magnetic regions having opposite magnetic orientations. For example, each primary magnet  1526  can include an inner arcuate magnetic region  1552  having a magnetic orientation in a first axial direction (as shown by polarity indicator  1553  in  FIG.  15 B ), an outer arcuate magnetic region  1554  having a magnetic orientation in a second axial direction opposite the first direction (as shown by polarity indicator  1555  in  FIG.  15 B ), and a central non-magnetized region  1556  that does not have a magnetic orientation. Central non-magnetized region  1556  can magnetically separate inner arcuate region  1552  from outer arcuate region  1554  by inhibiting magnetic fields from directly crossing through central region  1556 . Magnets having regions of opposite magnetic orientation separated by a non-magnetized region are sometimes referred to herein as having a “quad-pole” configuration. 
     In some embodiments, each secondary magnet  1526  can be made of a magnetic material that has been ground and shaped into an arcuate structure, and a magnetic orientation having a radial component in the transverse plane can be created, e.g., using a magnetizer. Similarly, each primary magnet  1526  can be made of a single piece of magnetic material that has been ground and shaped into an arcuate structure, and a magnetizer can be applied to the arcuate structure to induce an axial magnetic orientation in one direction within an inner arcuate region of the structure and an axial magnetic orientation in the opposite direction within an outer arcuate region of the structure, while demagnetizing or avoiding creation of a magnetic orientation in the central region. In some alternative embodiments, each primary magnet  1526  can be a compound structure with two arcuate pieces of magnetic material providing inner arcuate magnetic region  1552  and outer arcuate magnetic region  1554 ; in such embodiments, central non-magnetized region  1556  can be formed of an arcuate piece of nonmagnetic material or formed as an air gap defined by sidewalls of inner arcuate magnetic region  1552  and outer arcuate magnetic region  1554 . 
     As shown in  FIG.  15 B , the magnetic polarity of secondary magnet  1528  (shown by indicator  1517 ) can be oriented such that when primary alignment component  1516  and secondary alignment component  1518  are aligned, the south pole of secondary magnet  1528  is oriented toward the north pole of inner arcuate magnetic region  1552  (shown by indicator  1553 ) while the north pole of secondary magnet  1528  is oriented toward the south pole of outer arcuate magnetic region  1554  (shown by indicator  1555 ). Accordingly, the respective magnetic orientations of inner arcuate magnetic region  1552 , secondary magnet  1528  and outer arcuate magnetic region  1556  can generate magnetic fields  1540  that produce an attractive force between primary magnet  1526  and secondary magnet  1528 , thereby facilitating alignment between respective electronic devices in which primary alignment component  1516  and secondary alignment component  1518  are disposed (e.g., as shown in  FIG.  13   ). Shield  1514  can redirect some of magnetic fields  1540  away from regions below primary magnet  1526 . Further, the “closed-loop” magnetic field  1540  formed around central nonmagnetic region  1556  can have tight and compact field lines that do not stray from primary and secondary magnets  1526  and  1528  as far as magnetic field  1540  strays from primary and secondary magnets  226  and  228  in  FIG.  15 B . Thus, magnetically sensitive components can be placed relatively close to primary alignment component  1516  with reduced concern for stray magnetic fields. Accordingly, as compared to magnetic alignment system  200 , magnetic alignment system  1500  can help to reduce the overall size of a device in which primary alignment component  1516  is positioned and can also help reduce noise created by magnetic field  1540  in adjacent components or devices, such as a power-receiving device in which secondary alignment component  1518  is positioned. 
     It will be appreciated that magnetic alignment system  1500  is illustrative and that variations and modifications are possible. For instance, while primary alignment component  1516  and secondary alignment component  1518  are each shown as being constructed of eight arcuate magnets, other embodiments may use a different number of magnets, such as sixteen magnets, thirty-six magnets, or any other number of magnets, and the number of primary magnets need not be equal to the number of secondary magnets. In other embodiments, secondary alignment component  1518  can be formed of a single, monolithic annular magnet. Similarly, primary alignment component  1516  can be formed of a single, monolithic annular piece of magnetic material with an appropriate magnetization pattern as described above, or primary alignment component  1516  can be formed of a monolithic inner annular magnet and a monolithic outer annular magnet, with an annular air gap or region of non-magnetic material disposed between the inner annular magnet and outer annular magnet. In some embodiments, a construction using multiple arcuate magnets may improve manufacturing because smaller arcuate magnets are less brittle than a single, monolithic annular magnet and are less prone to yield loss due to physical stresses imposed on the magnetic material during manufacturing. It should also be understood that the magnetic orientations of the various magnetic alignment components or individual magnets do not need to align exactly with the lateral and axial directions. The magnetic orientation can have any angle that provides a closed-loop path for a magnetic field through the primary and secondary alignment components. 
     As noted above, in embodiments of magnetic alignment systems having closed-loop magnetic orientations, such as magnetic alignment system  1500 , secondary alignment component  1518  can have a magnetic orientation in the transverse plane. For example, in some embodiments, secondary alignment component  1518  can have a magnetic polarity in a radial orientation.  FIG.  16    shows a simplified top-down view of a secondary alignment component  1618  according to some embodiments having secondary magnets  1628   a - h  with radial magnetic orientations as shown by magnetic polarity indicators  1617   a - h . In this example, each secondary magnet  1628   a - h  has a north magnetic pole oriented toward the radially outward side and a south magnetic pole toward the radially inward side; however, this orientation can be reversed, and the north magnetic pole of each secondary magnet  1628   a - h  can be oriented toward the radially inward side while the south magnetic pole is oriented toward the radially outward side. 
       FIG.  17 A  shows a perspective view of a magnetic alignment system  1700  according to some embodiments. Magnetic alignment system  1700 , which can be an implementation of magnetic alignment system  1500 , includes a secondary alignment component  1718  having a radially outward magnetic orientation (e.g., as shown in  FIG.  16   ) and a complementary primary alignment component  1716 . In this example, magnetic alignment system  1700  includes a gap  1717  between two of the sectors; however, gap  1717  is optional and magnetic alignment system  1700  can be a complete annular structure. Also shown are components  1702 , which can include, for example an inductive coil assembly or other components located within the central region of primary magnetic alignment component  1716  or secondary magnetic alignment component  1718 . Magnetic alignment system  1700  can have a closed-loop configuration similar to magnetic alignment system  1500  (as shown in  FIG.  15 B ) and can include arcuate sectors  1701 , each of which can be made of one or more arcuate magnets. In some embodiments, the closed-loop configuration of magnetic alignment system  1700  can reduce or prevent magnetic field leakage that may affect components  1702 . 
       FIG.  17 B  shows an axial cross-section view through one of arcuate sectors  1701 . Arcuate sector  1701  includes a primary magnet  1726  and a secondary magnet  1728 . As shown by orientation indicator  1719 , secondary magnet  1728  has a magnetic polarity oriented in a radially outward direction, i.e., the north magnetic pole is toward the radially outward side of magnetic alignment system  1700 . Like primary magnets  1526  described above, primary magnet  1726  includes an inner arcuate magnetic region  1752 , an outer arcuate magnetic region  1754 , and a central non-magnetized region  1756  (which can include, e.g., an air gap or a region of nonmagnetic or non-magnetized material). Inner arcuate magnetic region  1752  has a magnetic polarity oriented axially such that the north magnetic pole is toward secondary magnet  1728 , as shown by indicator  1753 , while outer arcuate magnetic region  1754  has an opposite magnetic orientation, with the south magnetic pole oriented toward secondary magnet  1728 , as shown by indicator  1755 . As described above with reference to  FIG.  15 B , the arrangement of magnetic orientations shown in  FIG.  17 B  results in magnetic attraction between primary magnet  1726  and secondary magnet  1728 . In some embodiments, the magnetic polarities can be reversed such that the north magnetic pole of secondary magnet  1728  is oriented toward the radially inward side of magnetic alignment system  1700 , the north magnetic pole of outer arcuate region  1754  of primary magnet  1726  is oriented toward secondary magnet  1728 , and the north magnetic pole of inner arcuate region  1752  is oriented away from secondary magnet  1728 . 
     When primary alignment component  1716  and secondary alignment component  1718  are aligned, the radially symmetrical arrangement and directional equivalence of magnetic polarities of primary alignment component  1716  and secondary alignment component  1718  allow secondary alignment component  1718  to rotate freely (relative to primary alignment component  1716 ) in the clockwise or counterclockwise direction in the lateral plane while maintaining alignment along the axis. 
     As used herein, a “radial” orientation need not be exactly or purely radial. For example,  FIG.  17 C  shows a secondary arcuate magnet  1738  according to some embodiments. Secondary arcuate magnet  1738  has a purely radial magnetic orientation, as indicated by arrows  1739 . Each arrow  1739  is directed at the center of curvature of magnet  1738 ; if extended inward, arrows  1739  would converge at the center of curvature. However, achieving this purely radial magnetization requires that magnetic domains within magnet  1738  be oriented obliquely to neighboring magnetic domains. For some types of magnetic materials, purely radial magnetic orientation may not be practical. Accordingly, some embodiments use a “pseudo-radial” magnetic orientation that approximates the purely radial orientation of  FIG.  17 C .  FIG.  17 D  shows a secondary arcuate magnet  1748  with pseudo-radial magnetic orientation according to some embodiments. Magnet  1748  has a magnetic orientation, shown by arrows  1749 , that is perpendicular to a baseline  1751  connecting the inner corners  1757 ,  1759  of arcuate magnet  1748 . If extended inward, arrows  1749  would not converge. Thus, neighboring magnetic domains in magnet  1748  are parallel to each other, which is readily achievable in magnetic materials such as NdFeB. The overall effect in a magnetic alignment system, however, can be similar to the purely radial magnetic orientation shown  FIG.  17 C .  FIG.  17 E  shows a secondary annular alignment component  1758  made up of magnets  1748  according to some embodiments. Magnetic orientation arrows  1749  have been extended to the center point  1761  of annular alignment component  1758 . As shown the magnetic field direction can be approximately radial, with the closeness of the approximation depending on the number of magnets  1748  and the inner radius of annular alignment component  1758 . In some embodiments, 138 magnets  1748  can provide a pseudo-radial orientation; in other embodiments, more or fewer magnets can be used. It should be understood that all references herein to magnets having a “radial” magnetic orientation include pseudo-radial magnetic orientations and other magnetic orientations that are approximately but not purely radial. 
     In some embodiments, a radial magnetic orientation in a secondary alignment component  1718  (e.g., as shown in  FIG.  17 B ) provides a magnetic force profile between secondary alignment component  1718  and primary alignment component  1716  that is the same around the entire circumference of the magnetic alignment system. The radial magnetic orientation can also result in greater magnetic permeance, which allows secondary alignment component  1718  to resist demagnetization as well as enhancing the attractive force in the axial direction and improving shear force in the lateral directions when the two components are aligned. 
       FIGS.  18 A and  18 B  show graphs of force profiles for different magnetic alignment systems, according to some embodiments. Specifically,  FIG.  18 A  shows a graph  1800  of vertical attractive (normal) force in the axial (z) direction for different magnetic alignment systems of comparable size and using similar types of magnets. Graph  1800  has a horizontal axis representing displacement from a center of alignment, where 0 represents the aligned position and negative and positive values represent left and right displacements from the aligned position in arbitrary units, and a vertical axis showing the normal force (F NORMAL ) as a function of displacement in arbitrary units. For purposes of this description, F NORMAL  is defined as the magnetic force between the primary and secondary alignment components in the axial direction; F NORMAL &gt;0 represents attractive force while F NORMAL &lt;0 represents repulsive force. Graph  1800  shows normal force profiles for three different types of magnetic alignment systems. A first type of magnetic alignment system uses central alignment components, such as a pair of complementary disc-shaped magnets placed along an axis; a representative normal force profile for a “central” magnetic alignment system is shown as line  1801  (dot-dash line). A second type of magnetic alignment system uses annular alignment components with axial magnetic orientations, e.g., magnetic alignment system  1400  of  FIGS.  14 A and  14 B ; a representative normal force profile for such an annular-axial magnetic alignment system is shown as line  1803  (dashed line). A third type of magnetic alignment system uses annular alignment components with closed-loop magnetic orientations and radial symmetry (e.g., magnetic alignment system  1700  of  FIG.  17   ); a representative normal force profile for a radially symmetric closed-loop magnetic alignment system is shown as line  1805  (solid line). 
     Similarly,  FIG.  18 B  shows a graph  1820  of lateral (shear) force in a transverse direction for different magnetic alignment systems. Graph  1820  has a horizontal axis representing displacement from a center of alignment using the same convention and units as graph  1800 , and a vertical axis showing the shear force (F SHEAR ) as a function of direction in arbitrary units. For purposes of this description, F SHEAR  is defined as the magnetic force between the primary and secondary alignment components in the lateral direction; F SHEAR &gt;0 represents force toward the left along the displacement axis while F SHEAR &lt;0 represents force toward the right along the displacement axis. Graph  1820  shows shear force profiles for the same three types of magnetic alignment systems as graph  1800 : a representative shear force profile for a central magnetic alignment system is shown as line  1821  (dot-dash line); a representative shear force profile for an annular-axial magnetic alignment system is shown as line  1823  (dashed line); and a representative normal force profile for a radially symmetric closed-loop magnetic alignment system is shown as line  1825  (solid line). 
     As shown in  FIG.  18 A , each type of magnetic alignment system achieves the strongest magnetic attraction in the axial direction when the primary and secondary alignment components are in the aligned position ( 0  on the horizontal axis), as shown by respective peaks  1811 ,  1813 , and  1815 . While the most strongly attractive normal force is achieved in the aligned positioned for all systems, the magnitude of the peak depends on the type of magnetic alignment system. In particular, a radially-symmetric closed-loop magnetic alignment system (e.g., magnetic alignment system  1700  of  FIG.  17   ) provides stronger magnetic attraction when in the aligned position than the other types of magnetic alignment systems. This strong attractive normal force can overcome small misalignments due to frictional force and can achieve a more accurate and robust alignment between the primary and secondary alignment components, which in turn can provide a more accurate and robust alignment between a portable electronic device and a wireless charging device within which the magnetic alignment system is implemented. 
     As shown in  FIG.  18 B , the strongest shear forces (attractive or repulsive) are obtained when the primary and secondary alignment components are laterally just outside of the aligned position, e.g., at −2 and +2 units of separation from the aligned position, as shown by respective peaks  1831   a - b ,  1833   a - b , and  1835   a - b . Similarly to the normal force, the magnitude of the peak strength of shear force depends on the type of magnetic alignment system. In particular, a radially-symmetric closed-loop magnetic alignment system (e.g., magnetic alignment system  1700  of  FIG.  17   ) provides higher magnitude of shear force when just outside of the aligned position than the other types of magnetic alignment systems. This strong shear force can provide tactile feedback to help the user identify when the two components are aligned. In addition, like the strong normal force, the strong shear force can overcome small misalignments due to frictional force and can achieve a more accurate and robust alignment between the primary and secondary alignment components, which in turn can provide a more accurate and robust alignment between a portable electronic device and a wireless charging device within which the magnetic alignment system is implemented. 
     A radially-symmetric closed-loop magnetic alignment system (e.g., magnetic alignment system  1700  of  FIG.  17   ) can provide accurate and robust alignment in the axial and lateral directions. Further, because of the radial symmetry, the alignment system does not have a preferred rotational orientation in the lateral plane about the axis; the shear force profile is the same regardless of relative rotational orientation of the electronic devices being aligned. 
     In some embodiments, a closed-loop magnetic alignment system can be designed to provide one or more preferred rotational orientations.  FIG.  19    shows a simplified top-down view of a secondary alignment component  1918  according to some embodiments. Secondary alignment component  1918  includes sectors  1928   a - h  with radial magnetic orientations as shown by magnetic polarity indicators  1917   a - h . Each of sectors  1928   a - h  can include one or more secondary arcuate magnets (not shown). In this example, secondary magnets in sectors  1928   b ,  1928   d ,  1928   f , and  1928   h  each have a north magnetic pole oriented toward the radially outward side and a south magnetic pole toward the radially inward side, while secondary magnets in sectors  1928   a ,  1928   c ,  1928   e , and  1928   g  each have a north magnetic pole oriented toward the radially inward side and a south magnetic pole toward the radially outward side. In other words, magnets in sectors  1928   a - h  of secondary alignment component  1918  have alternating magnetic orientations. A complementary primary alignment component can have sectors with correspondingly alternating magnetic orientations. 
     For example,  FIG.  20 A  shows a perspective view of a magnetic alignment system  2000  according to some embodiments. Magnetic alignment system  2000  includes a secondary alignment component  2018  having alternating radial magnetic orientations (e.g., as shown in  FIG.  19   ) and a complementary primary alignment component  2016 . Some of the arcuate sections of magnetic alignment system  2000  are not shown in order to reveal internal structure; however, it should be understood that magnetic alignment system  2000  can be a complete annular structure. Also shown are components  2002 , which can include, for example, inductive coil assemblies or other components located within the central region of primary annular alignment component  2016  and/or secondary annular alignment component  2018 . Magnetic alignment system  2000  can be a closed-loop magnetic alignment system similar to magnetic alignment system  1500  described above and can include arcuate sectors  2001   b ,  2001   c  of alternating magnetic orientations, with each arcuate sector  2001   b ,  2001   c  including one or more arcuate magnets in each of primary annular alignment component  2016  and secondary annular alignment component  2018 . In some embodiments, the closed-loop configuration of magnetic alignment system  2000  can reduce or prevent magnetic field leakage that may affect component  2002 . 
       FIG.  20 B  shows an axial cross-section view through one of arcuate sectors  2001   b , and  FIG.  20 C  shows an axial cross-section view through one of arcuate sectors  2001   c . Arcuate sector  2001   b  includes a primary magnet  2026   b  and a secondary magnet  2028   b . As shown by orientation indicator  2017   b , secondary magnet  2028   b  has a magnetic polarity oriented in a radially outward direction, i.e., the north magnetic pole is toward the radially outward side of magnetic alignment system  2000 . Like primary magnets  1526  described above, primary magnet  2026   b  includes an inner arcuate magnetic region  2052   b , an outer arcuate magnetic region  2054   b , and a central nonmagnetic region  2056   b  (which can include, e.g., an air gap or a region of nonmagnetic material). Inner arcuate magnetic region  2052   b  has a magnetic polarity oriented axially such that the north magnetic pole is toward secondary magnet  2028   b , as shown by indicator  2053   b , while outer arcuate magnetic region  2054   b  has an opposite magnetic orientation, with the south magnetic pole oriented toward secondary magnet  2028   b , as shown by indicator  2055   b . As described above with reference to  FIG.  15 B , the arrangement of magnetic orientations shown in  FIG.  20 B  results in magnetic attraction between primary magnet  2026   b  and secondary magnet  2028   b.    
     As shown in  FIG.  20 C , arcuate sector  2001   c  has a “reversed” magnetic orientation relative to arcuate sector  2001   b . Arcuate sector  2001   c  includes a primary magnet  2026   c  and a secondary magnet  2028   c . As shown by orientation indicator  2017   c , secondary magnet  2028   c  has a magnetic polarity oriented in a radially inward direction, i.e., the north magnetic pole is toward the radially inward side of magnetic alignment system  2000 . Like primary magnets  1526  described above, primary magnet  2026   c  includes an inner arcuate magnetic region  2052   c , an outer arcuate magnetic region  2054   c , and a central nonmagnetic region  2056   c  (which can include, e.g., an air gap or a region of nonmagnetic material). Inner arcuate magnetic region  2052   c  has a magnetic polarity oriented axially such that the south magnetic pole is toward secondary magnet  2028   c , as shown by indicator  2053   c , while outer arcuate magnetic region  2054   c  has an opposite magnetic orientation, with the north magnetic pole oriented toward secondary magnet  2028   c , as shown by indicator  2055   c . As described above with reference to  FIG.  15 B , the arrangement of magnetic orientations shown in  FIG.  20 C  results in magnetic attraction between primary magnet  2026   c  and secondary magnet  2028   c.    
     An alternating arrangement of magnetic polarities as shown in  FIGS.  19  and  20 A- 20 C  can create a “ratcheting” feel when secondary alignment component  2018  is aligned with primary alignment component  2016  and one of alignment components  2016 ,  2018  is rotated relative to the other about the common axis. For instance, as secondary alignment component  2018  is rotated relative to primary alignment component  2016 , radially-outward magnet  2028   b  alternately come into proximity with a complementary magnet  2026   b  of primary alignment component  2016 , resulting in an attractive magnetic force, and with an anti-complementary magnet  2026   c  of primary alignment component  2016 , resulting in a repulsive magnetic force. If primary magnets  2026   b ,  2026   c  and secondary magnets  2028   b ,  2028   c  have the same angular size and spacing, in any given orientation, each pair of magnets will experience similar net attractive or repulsive magnetic forces such that alignment is stable and robust in rotational orientations in which complementary magnet pairs  2026   b ,  2028   b  and  2026   c ,  2028   c  are in proximity. In other rotational orientations, a torque toward a stable rotational orientation can be experienced. 
     In the examples shown in  FIGS.  19  and  20 A through  20 C , each sector includes one magnet, and the direction of magnetic orientation alternates with each magnet. In some embodiments, a sector can include two or more magnets having the same direction of magnetic orientation. For example,  FIG.  21 A  shows a simplified top-down view of a secondary alignment component  2118  according to some embodiments. Secondary alignment component  2118  includes secondary magnets  2128   b  with radially outward magnetic orientations and secondary magnets  2128   c  with radially inward orientations, similarly to secondary alignment component  2018  described above. In this example, the magnets are arranged such that a pair of outwardly-oriented magnets  2128   b  (forming a first sector) are adjacent to a pair of inwardly-oriented magnets  2128   c  (forming a second sector adjacent to the first sector). The pattern of alternating sectors (with two magnets per sector) repeats around the circumference of secondary alignment component  2118 . Similarly,  FIG.  21 B  shows a simplified top-down view of another secondary alignment component  2118 ′ according to some embodiments. Secondary alignment component  2118 ′ includes secondary magnets  2128   b  with radially outward magnetic orientations and secondary magnets  2128   c  with radially inward orientations. In this example, the magnets are arranged such that a group of four radially-outward magnets  2128   b  (forming a first sector) is adjacent to a group of four radially-inward magnets  2128   c  (forming a second sector adjacent to the first sector). The pattern of alternating sectors (with four magnets per sector) repeats around the circumference of secondary alignment component  2118 ′. Although not shown in  FIGS.  21 A and  21 B , the structure of a complementary primary alignment component for secondary alignment component  2118  or  2118 ′ should be apparent in view of  FIGS.  20 A- 20 C . A shear force profile for the alignment components of  FIGS.  21 A and  21 B  can be similar to the ratcheting profile described above, although the number of rotational orientations that provide stable alignment will be different. 
     In other embodiments, a variety of force profiles can be created by changing the alignment of different component magnets of the primary and/or secondary alignment components. As just one example,  FIG.  22    shows a simplified top-down view of a secondary alignment component  2218  according to some embodiments having sectors  2228   a - h  with location-dependent magnetic orientations as shown by magnetic polarity indicators  2217   a - h . In this example, secondary alignment component  2218  can be regarded as bisected by bisector line  2201 , which defines two halves of secondary alignment component  2218 . In a first half  2203 , sectors  2228   e - h  have magnetic polarities oriented radially outward, similarly to examples described above. 
     In the second half  2205 , sectors  2228   a - d  have magnetic polarities oriented substantially parallel to bisector line  2201  rather than radially. In particular, sectors  2228   a  and  2228   b  have magnetic polarities oriented in a first direction parallel to bisector line  2201 , while sectors  2228   c  and  2228   d  have magnetic polarities oriented in the direction opposite to the direction of the magnetic polarities of sectors  2228   a  and  2228   b . A complementary primary alignment component can have an inner annular region with magnetic north pole oriented toward secondary alignment component  2218 , an outer annular region with magnetic north pole oriented away from secondary alignment component  2218 , and a central non-magnetized region, providing a closed-loop magnetic orientation as described above. The asymmetric arrangement of magnetic orientations in secondary alignment component  2218  can modify the shear force profile such that secondary alignment component  2218  generates less shear force in the direction toward second half  2205  than in the direction toward first half  2203 . In some embodiments, an asymmetrical arrangement of this kind can be used where the primary alignment component is mounted in a docking station and the secondary alignment component is mounted in a portable electronic device that docks with the docking station. Assuming secondary annular alignment component  2218  is oriented in the portable electronic device such that half-annulus  2205  is toward the top of the portable electronic device, the asymmetric shear force can facilitate an action of sliding the portable electronic device downward to dock with the docking station or upward to remove it from the docking station, while still providing an attractive force to draw the portable electronic device into a desired alignment with the docking station. 
     It will be appreciated that the foregoing examples are illustrative and not limiting. Sectors of a primary and/or secondary alignment component can include magnetic elements with the magnetic polarity oriented in any desired direction and in any combination, provided that the primary and secondary alignment components of a given magnetic alignment system have complementary magnetic orientations to provide forces toward the desired position of alignment. Different combinations of magnetic orientations may create different shear force profiles, and the selection of magnetic orientations may be made based on a desired shear force profile. 
     In various embodiments described above, a magnetic alignment system can provide robust alignment in a lateral plane and may or may not provide rotational alignment. For example, radially symmetric magnetic alignment system  1700  of  FIGS.  17 A- 17 B  may not define a preferred rotational orientation. Radially alternating magnetic alignment system  2000  of  FIGS.  20 A- 20 C  can define multiple equally preferred rotational orientations. For some applications, such as alignment of a portable electronic device with a wireless charging puck, rotational orientation may not be a concern. In other applications, such as alignment of a portable electronic device in an attachment device, such as attachment device  100 , attachment device  300 , attachment device  500  (shown above) a docking station or upright holder, a particular rotational alignment may be desirable. Accordingly, in some embodiments an annular magnetic alignment system can be augmented with one or more rotational alignment components that can be positioned externally to and spaced apart from the annular magnetic alignment components to help guide devices into a target rotational orientation relative to each other. 
       FIG.  23    shows an example of a magnetic alignment system with an annular alignment component and a rotational alignment component according to some embodiments. In this example, primary alignment components of the magnetic alignment system are included in an accessory device  2302 , and secondary alignment components of the magnetic alignment system are included in a portable electronic device  2304 . Portable electronic device  2304  can be, for example, a smart phone whose front surface provides a touchscreen display and whose back surface is designed to support wireless charging. Accessory device  2302  can be, for example, a charging dock that supports portable electronic device  2304  such that its display is visible and accessible to a user.  FIG.  23    shows proximal surfaces of portable electronic device  2304  and accessory  2302 . For instance, accessory device  2302  can support portable electronic device  2304  such that the display is vertical or at a conveniently tilted angle for viewing and/or touching. In the example shown, accessory device  2302  supports portable electronic device  2304  in a “portrait” orientation (shorter sides of the display at the top and bottom); however, in some embodiments accessory device  2302  can support portable electronic device  2304  in a “landscape” orientation (longer sides of the display at the top and bottom). Accessory device  2302  can also be mounted on a swivel, gimbal, or the like, allowing the user to adjust the orientation of portable electronic device  2304  by adjusting the orientation of accessory device  2302 . 
     Accessory device  2302  can be used as all or part of attachment device  100 , attachment device  300 , or attachment device  500 , all shown above, or as all or part of another attachment device according to an embodiment of the present invention. 
     As described above, components of a magnetic alignment system can include a primary annular alignment component  2316  disposed in accessory  2302  and a secondary annular alignment component  2318  disposed in portable electronic device. Primary annular alignment component  2316  can be similar or identical to any of the primary alignment components described above. For example, primary annular alignment component  2316  can be formed of arcuate magnets  2326  arranged in an annular configuration. Although not shown in  FIG.  23   , one or more gaps can be provided in primary annular alignment component  2316 , e.g., by omitting one or more of arcuate magnets  2326  or by providing a gap at one or more interfaces  2330  between adjacent arcuate magnets  2326 . In some embodiments, each arcuate magnet  2326  can include an inner region having a first magnetic orientation (e.g., axially oriented in a first direction) and an outer region having a second magnetic orientation opposite the first magnetic orientation (e.g., axially oriented opposite the first direction), with a non-magnetized gap region between the inner and outer regions (which can include an air gap or a nonmagnetic material). In some embodiments, primary annular alignment component can also include a shield (not shown) on the distal side of arcuate magnets  2326 . 
     Likewise, secondary annular alignment component  2318  can be similar or identical to any of the secondary alignment components described above. For example, secondary annular alignment component  2318  can be formed of arcuate magnets  2328  arranged in an annular configuration. Although not shown in  FIG.  23   , one or more gaps can be provided in secondary annular alignment component  2318 , e.g., by omitting one or more arcuate magnets  2328  or by providing a gap at one or more interfaces  2332  between adjacent magnets  2328 . As described above, arcuate magnets  2328  can provide radially-oriented magnetic polarities. For instance, all sectors of secondary annular alignment component  2318  can have a radially-outward magnetic orientation or a radially-inward magnetic orientation, or some sectors of secondary annular alignment component  2318  may have a radially-outward magnetic orientation while other sectors of secondary annular alignment component  2318  have a radially-inward magnetic orientation. 
     As described above, primary annular alignment component  2316  and secondary annular alignment component  2318  can provide shear forces that promote alignment in the lateral plane so that center point  2301  of primary annular alignment component  2316  aligns with center point  2303  of secondary annular alignment component  2318 . However, primary annular alignment component  2316  and secondary annular alignment component  2318  might not provide shear forces that favor any particular rotational orientation, such as portrait orientation. 
     Accordingly, in some embodiments, a magnetic alignment system can incorporate one or more rotational alignment components in addition to the annular alignment components. The rotational alignment components can include one or more magnets that provide torque about the common axis of the (aligned) annular alignment components, so that a preferred rotational orientation can be reliably established. For example, as shown in  FIG.  23   , a primary rotational alignment component  2322  can be disposed outside of and spaced apart from primary annular alignment component  2316  while a secondary rotational alignment component  2324  is disposed outside of and spaced apart from secondary annular alignment component  2318 . Secondary rotational alignment component  2324  can be positioned at a fixed distance (y 0 ) from center point  2303  of secondary annular alignment component  2318  and centered between the side edges of portable electronic device  2304  (as indicated by distance xo from either side edge). Similarly, primary rotational alignment component  2322  can be positioned at the same distance y 0  from center point  2301  of primary annular alignment component  2316  and located at a rotational angle that results in a torque profile that favors the desired orientation of portable electronic device  2304  relative to accessory  2302  when secondary rotational alignment component  2324  is aligned with primary rotational alignment component  2322 . It should be noted that the same distance y 0  can be applied in a variety of portable electronic devices having different form factors, so that a single accessory can be compatible with a family of portable electronic devices. A longer distance y 0  can increase torque toward the preferred rotational alignment; however, the maximum distance y 0  may be limited by design considerations, such as the size of the smallest portable electronic device in a family of portable electronic devices that incorporate mutually compatible magnetic alignment systems. 
     According to some embodiments, each of primary rotational alignment component  2322  and secondary rotational alignment component  2324  can be implemented using one or more rectangular or square blocks of magnetic material each of which has each been magnetized such that its magnetic polarity is oriented in a desired direction. The magnetic orientations of rotational alignment components  2322  and  2324  can be complementary so that an attractive magnetic force is generated when the proximal surfaces of rotational alignment components  2322  and  2324  are near each other. This attractive magnetic force can help to rotate portable electronic device  2304  and accessory  2302  into a preferred rotational orientation in which the proximal surfaces of rotational alignment components  2322  and  2324  are in closest proximity to each other. Examples of magnetic orientations for rotational alignment components  2322  and  2324  that can be used to provide a desired attractive force are described below. In some embodiments, primary rotational alignment component  2322  and secondary rotational alignment component  2324  can have the same lateral dimensions and the same thickness. The dimensions can be chosen based on a desired magnetic field strength, the dimensions of devices in which the rotational alignment components are to be deployed, and other design considerations. In some embodiments, the lateral dimensions can be about 6 mm by about 23 mm, and the thickness can be anywhere from about 0.3 mm to about 1.5 mm. In some embodiments, each of primary rotational alignment component  2322  and secondary rotational alignment component  2324  can be implemented using multiple rectangular blocks of magnetic material positioned adjacent to each other. As in other embodiments, a small gap may be present between adjacent magnets, e.g., due to manufacturing tolerances. 
       FIGS.  24 A and  24 B  show an example of rotational alignment according to some embodiments. In  FIG.  24 A , accessory  2302  is placed on the back surface of portable electronic device  2304  such that primary annular alignment component  2316  and secondary alignment component  2318  are aligned with each other in the lateral plane (which is the plane of the page in  FIG.  24 A ); in the view shown, center point  2301  of primary annular alignment component  2316  overlies center point  2303  of secondary annular alignment component  2318  A relative rotation is present such that rotational alignment components  2322  and  2324  are not aligned. In this configuration, an attractive force between rotational alignment components  2322  and  2324  can help guide portable electronic device  2304  and accessory  2302  into a target rotational orientation as shown in  FIG.  17 B . In  FIG.  24 B , the attractive magnetic force between rotational alignment components  2322  and  2324  has brought portable electronic device  2304  and accessory  2302  into the target rotational alignment with the sides of portable electronic device  2304  parallel to the sides of accessory  2302 . In some embodiments, the same attractive magnetic force between rotational alignment components  2322  and  2324  can help to hold portable electronic device  2304  and accessory  2302  in a fixed rotational alignment. 
     Rotational alignment components  2322  and  2324  can have various patterns of magnetic orientations. As long as the magnetic orientations of rotational alignment components  2322  and  2324  are complementary to each other, a torque toward the target rotational orientation can be present when the devices are brought into lateral alignment and close to the target rotational orientation.  FIGS.  25 A- 28 B  show examples of magnetic orientations for a rotational alignment component according to various embodiments. While the magnetic orientation is shown for only one rotational alignment component, it should be understood that the magnetic orientation of a complementary rotational alignment component can be complementary to (e.g., the reverse of) the magnetic orientation of shown. 
       FIGS.  25 A and  25 B  show a perspective view and a top view of a rotational alignment component  2524  having a “z-pole” configuration according to some embodiments. It should be understood that the perspective view is not to any particular scale and that the lateral (xy) dimensions and axial (z) thickness can be varied as desired. As shown in  FIG.  25 A , rotational alignment component  2524  can have a uniform magnetic orientation along the axial direction, as indicated by arrows  2505 . Accordingly, as shown in  FIG.  25 B , a north magnetic pole (N) may be nearest the proximal surface  2503  of rotational alignment component  2524 . A complementary z-pole alignment component can have a uniform magnetic orientation with a south magnetic pole nearest the proximal surface. The z-pole configuration can provide reliable alignment. 
     Other configurations can provide reliable alignment as well as a stronger, or more salient, “clocking” sensation for the user. A “clocking sensation,” as used herein, refers to a user-perceptible torque about the common axis of the annular alignment components that pulls toward the target rotational alignment and/or resists small displacements from the target rotational alignment. A greater variation of torque as a function of rotational angle can provide a more salient clocking sensation. Following are examples of magnetization configurations for a rotational alignment component that can provide more salient clocking sensations than the z-pole configuration of  FIGS.  25 A and  25 B . 
       FIGS.  26 A and  26 B  show a perspective view and a top view of a rotational alignment component  2624  having a “quad pole” configuration according to some embodiments. It should be understood that the perspective view is not to any particular scale and that the lateral (xy) dimensions and axial (z) thickness can be varied as desired. As shown in  FIG.  26 A , rotational alignment component  2624  has a first magnetized region  2625  with a magnetic orientation along the axial direction such that the north magnetic pole (N) is nearest the proximal (+z) surface  2603  of rotational alignment component  2624  (as indicated by arrow  2605 ) and a second magnetized region  2627  with a magnetic orientation opposite to the magnetic orientation of the first region such that the south magnetic pole (S) is nearest to proximal surface  2603  (as indicated by arrows  2607 ). Between magnetized regions  2625  and  2627  is a neutral region  2629  that is not magnetized. In some embodiments, rotational alignment component  2624  can be formed from a single piece of magnetic material that is exposed to a magnetizer to create regions  2625 ,  2627 ,  2629 . Alternatively, rotational alignment component  2624  can be formed using two pieces of magnetic material with a nonmagnetic material or an air gap between them. As shown in  FIG.  26 B , the proximal surface of rotational alignment component  2624  can have one region having a “north” polarity and another region having a “south” polarity. A complementary quad-pole rotational alignment component can have corresponding regions of south and north polarity at the proximal surface. 
       FIGS.  27 A and  27 B  show a perspective view and a top view of a rotational alignment component  2724  having an “annulus design” configuration according to some embodiments. It should be understood that the perspective view is not to any particular scale and that the lateral (xy) dimensions and axial (z) thickness can be varied as desired. As shown in  FIG.  27 A , rotational alignment component  2724  has an outer magnetized region  2725  with a magnetic orientation along the axial direction such that the north magnetic pole (N) is nearest the proximal (+z) surface  2703  of rotational alignment component  2724  (as shown by arrows  2705 ) and an inner magnetized region  2727  with a magnetic orientation opposite to the magnetic orientation of the first region such that the south magnetic pole (S) is nearest to proximal surface  2703 . Between magnetized regions  2725  and  2727  is a neutral annular region  2729  that is not magnetized. In some embodiments, rotational alignment component  2724  can be formed from a single piece of magnetic material that is exposed to a magnetizer to create regions  2725 ,  2727 ,  2729 . Alternatively, rotational alignment component  2724  can be formed using two or more pieces of magnetic material with a nonmagnetic material or an air gap between them. As shown in  FIG.  27 B , the proximal surface of rotational alignment component  2724  can have an annular outer region having a “north” polarity and an inner region having a “south” polarity. The proximal surface of a complementary annulus-design rotational alignment component can have an annular outer region of south polarity and an inner region of north polarity. 
       FIGS.  28 A and  28 B  show a perspective view and a top view of a rotational alignment component  2824  having a “triple pole” configuration according to some embodiments. It should be understood that the perspective view is not to any particular scale and that the lateral (xy) dimensions and axial (z) thickness can be varied as desired. As shown in  FIG.  28 A , rotational alignment component  2824  has a central magnetized region  2825  with a magnetic orientation along the axial direction such that the south magnetic pole (S) is nearest the proximal (+z) surface  2803  of rotational alignment component  2824  (as shown by arrow  2805 ) and outer magnetized regions  2827 ,  2829  with a magnetic orientation opposite to the magnetic orientation of central region  2825  such that the north magnetic pole (N) is nearest to proximal surface  2803  (as shown by arrows  2807 ,  2809 ). Between central magnetized region  2825  and each of outer magnetized regions  2827 ,  2829  is a neutral region  2831 ,  2833  that is not strongly magnetized. In some embodiments, rotational alignment component  2824  can be formed from a single piece of magnetic material that is exposed to a magnetizer to create regions  2825 ,  2827 ,  2829 . Alternatively, rotational alignment component  2824  can be formed using three (or more) pieces of magnetic material with nonmagnetic materials or air gaps between them. As shown in  FIG.  28 B , the proximal surface may have a central region having a “south” polarity with an outer region having “north” polarity to either side. The proximal surface of a complementary triple-pole rotational alignment component can have a central region of north polarity with an outer region of south polarity to either side. 
     It should be understood that the examples in  FIGS.  25 A- 28 B  are illustrative and that other configurations may be used. The selection of a magnetization pattern for a rotational alignment component can be independent of the magnetization pattern of an annular alignment component with which the rotational alignment component is used. 
     In some embodiments, the selection of a magnetization pattern for a rotational alignment component can be based on optimizing the torque profile. For example, as noted above, it may be desirable to provide a strong tactile “clocking” sensation to a user when close to the desired rotational alignment. The clocking sensation can be a result of torque about a rotational axis defined by the annular alignment components. The amount of torque depends on various factors, including the distance between the axis and the rotational alignment component (distance y 0  in  FIG.  23   ), as well as the strength of the magnetic fields of the rotational alignment components (which may depend on the size of the rotational alignment components) and whether the annular alignment components exert any torque toward a preferred rotational orientation. 
       FIG.  29    shows graphs of torque as a function of angular rotation (in degrees) for an alignment system of the kind shown in  FIG.  23   , for different magnetization configurations of the rotational alignment component according to various embodiments. Angular rotation is defined such that zero degrees corresponds to the target rotational alignment (where the proximal surfaces of rotational angular components  2322  and  2324  are in closest proximity, e.g., as shown in  FIG.  24 B ). Torque is defined such that positive (negative) values indicate force in the direction of decreasing (increasing) rotational angle. For purpose of generating the torque profiles, it is assumed that annular alignment components  2316  and  2318  are rotationally symmetric and do not exert torque about the z axis defined by center points  2301  and  2303 . Three different magnetization configurations are considered. Line  2904  corresponds to the quad-pole configuration of  FIGS.  26 A and  26 B . Line  2905  corresponds to the annulus design configuration of  FIGS.  27 A and  27 B . Line  2906  corresponds to the triple-pole configuration of  FIGS.  28 A and  28 B . As shown, the annulus design (line  2905 ) and triple-pole (line  2906 ) configurations provide a sharper peak in the torque and therefore a more salient clocking sensation for the user, as compared to the quad-pole configuration (line  2904 ). In addition, the triple-pole configuration provides a stronger peak torque and therefore a more salient clocking sensation than the annulus-design configuration. It should be understood that the numerical values in  FIG.  29    are illustrative, and that torque in a particular embodiment may depend on a variety of other factors in addition to the magnetization configuration, such as the magnet volume, aspect ratio, and distance y0 from the center of the annular alignment component. 
     In the examples shown above, a single rotational alignment component is placed outside the annular alignment component at a distance y 0  from the center of the annular alignment component. This arrangement allows a single magnetic element to generate enough torque to produce a salient clocking sensation for a user aligning devices. In some embodiments, other arrangements are also possible. For example,  FIG.  30    shows a portable electronic device  3004  having an alignment system  3000  with multiple rotational alignment components according to some embodiments. In this example, alignment system  3000  includes an annular alignment component  3018  and a set of rotational alignment components  3024  positioned at various locations around the perimeter of annular alignment component  3018 . In this example, there are four rotational alignment components  3024  positioned at angular intervals of approximately 90 degrees. In other embodiments, different numbers and spacing of rotational alignment components can be used. Each rotational alignment component  3024  can have any of the magnetization configurations described above, including z-pole, quad-pole, triple-pole, or annulus-design configurations, or a different configuration. Further, different rotational alignment components  3024  can have different magnetization configurations from each other. It should be noted that rotational alignment components  3024  can be placed close to the perimeter of annular alignment component  3018 , and the larger number of magnetic components can provide increased torque at a smaller radius. Complementary rotation alignment components can be disposed around the outer perimeter of any type of annular alignment component (e.g., primary alignment components, secondary alignment components, or annular alignment components as described herein). 
     It will be appreciated that the foregoing examples of rotational alignment components are illustrative and that variations or modifications are possible. In some embodiments, a rotational alignment component can be provided as an optional adjunct to an annular alignment component, and a device that has both an annular alignment component and a rotational alignment component can align laterally to any other device that has a complementary annular alignment component, regardless of whether the other device has or does not have a rotational alignment component. Thus, for example, portable electronic device  2304  of  FIG.  23    can align rotationally to accessory  2302  (which has both annular alignment component  2316  and rotational alignment component  2322 ) as well as aligning laterally to another accessory (such as attachment device  100 , attachment device  300 , or attachment device  500 ) that has annular alignment component  2316  but not rotational alignment component  2322 . In the latter case, lateral alignment can be achieved, e.g., to support efficient wireless charging, but there may be no preferred rotational alignment, or rotational alignment may be achieved using a non-magnetic feature (e.g., a mechanical retention feature such as a ledge, a clip, a notch, or the like). A rotational alignment component can be used together with any type of annular alignment component (e.g., primary alignment components, secondary alignment components, or annular alignment components as described herein). 
     In embodiments described above, it is assumed (though not required) that the magnetic alignment components are fixed in position relative to the device enclosure and do not move in the axial or lateral direction. This provides a fixed magnetic flux. In some embodiments, it may be desirable for one or more of the magnetic alignment components to move in the axial direction. For example, in various embodiments of the present invention, it can be desirable to limit the magnetic flux provided by these magnetic structures. Limiting the magnetic flux can help to prevent the demagnetization of various charge and payment cards that a user might be carrying with an electronic device that incorporates one of these magnetic structures. But in some circumstances, it can be desirable to increase this magnetic flux in order to increase a magnetic attraction between an electronic device and an accessory or a second electronic device. Also, it can be desirable for one or more of the magnetic alignment components to move laterally. For example, an electronic device and an attachment structure or wireless device can be offset from each other in a lateral direction. The ability of a magnetic alignment component to move laterally can compensate for this offset and improve coupling between devices, particularly where a coil moves with the magnetic alignment component. Accordingly, embodiments of the present invention can provide structures where some or all of the magnets in these magnetic structures are able to change positions or otherwise move. Examples of magnetic structures having moving magnets are shown in the following figures. 
       FIGS.  31 A through  31 C  illustrate examples of moving magnets according to an embodiment of the present invention. In these examples, first electronic device  3100  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  3110  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  31 A , moving magnet  3110  can be housed in a first electronic device  3100 . First electronic device  3100  can include device enclosure  3130 , magnet  3110 , and shield  3120 . Magnet  3110  can be in a first position (not shown) adjacent to nonmoving shield  3120 . In this position, magnet  3110  can be separated from device enclosure  3130 . As a result, the magnetic flux  3112  at a surface of device enclosure  3130  can be relatively low, thereby protecting magnetic devices and magnetically stored information, such as information stored on payment cards. As magnet  3110  in first electronic device  3100  is attracted to a second magnet (not shown) in a second electronic device (not shown), magnet  3110  can move, for example it can move away from shield  3120  to be adjacent to device enclosure  3130 , as shown. With magnet  3110  at this location, magnetic flux  3112  at surface of device enclosure  3130  can be relatively high. This increase in magnetic flux  3112  can help to attract the second electronic device to first electronic device  3100 . 
     With this configuration, it can take a large amount of magnetic attraction for magnet  3110  to separate from shield  3120 . Accordingly, these and other embodiments of the present invention can include a shield that is split into a shield portion and a return plate portion. For example, in  FIG.  31 B , line  3160  can be used to indicate a split of shield  3120  into a shield  3140  and return plate  3150 . 
     In  FIG.  31 C , moving magnet  3110  can be housed in first electronic device  3100 . First electronic device  3100  can include device enclosure  3130 , magnet  3110 , shield  3140 , and return plate  3150 . In the absence of a magnetic attraction, magnet  3110  can be in a first position (not shown) such that shield  3140  can be adjacent to return plate  3150 . Again, in this configuration, magnetic flux  3112  at a surface of device enclosure  3130  can be relatively low. As magnet  3110  and first electronic device is attracted to a second magnet (not shown) in a second electronic device (not shown), magnet  3110  can move, for example it can move away from return plate  3150  to be adjacent to device enclosure  3130 , as shown. In this configuration, shield  3140  can separate from return plate  3150  and the magnetic flux  3112  at a surface of device enclosure  3130  can be increased. As before, this increase in magnetic flux  3112  can help to attract the second electronic device to the first electronic device  3100 . 
     In these and other embodiments of the present invention, various housings and structures can be used to guide a moving magnet. Also, various surfaces can be used in conjunction with these moving magnets. These surfaces can be rigid. Alternatively, these surfaces can be compliant and at least somewhat flexible. Examples are shown in the following figures. 
       FIGS.  32 A and  32 B  illustrate a moving magnetic structure according to an embodiment of the present invention. In this example, first electronic device  3200  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  3210  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above).  FIG.  32 A  illustrates a moving first magnet  3210  in a first electronic device  3200 . First electronic device  3200  can include first magnet  3210 , protective surface  3212 , housings  3220  and  3222 , compliant structure  3224 , shield  3240 , and return plate  3250 . In this figure, first magnet  3210  is not attracted to a second magnet (not shown), and therefore shield  3240  is magnetically attracted to or attached to return plate  3250 . In this position, compliant structure  3224  can be expanded or relaxed. Compliant structure  3224  can be formed of an elastomer, silicon rubber open cell foam, silicon rubber, polyurethane foam, or other foam or other compressible material. 
     In  FIG.  32 B , second electronic device  3260  has been brought into proximity of first electronic device  3200 . Second magnet  3270  can attract first magnet  3210 , thereby causing shield  3240  and return plate  3250  to separate from each other. Housings  3220  and  3222  can compress compliant structure  3224 , thereby allowing protective surface  3212  of first electronic device  3200  to move towards or adjacent to housing  3280  of second electronic device  3260 . Second magnet  3270  can be held in place in second electronic device  3260  by housing  3290  or other structure. As second electronic device  3260  is removed from first electronic device  3200 , first magnet  3210  and shield  3240  can be magnetically attracted to return plate  3250 , as shown in  FIG.  32 A . 
       FIGS.  33 A and  33 B  illustrate moving magnetic structures according to an embodiment of the present invention. In this example, first electronic device  3300  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  3310  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above).  FIG.  33 A  illustrates a moving first magnet  3310  in a first electronic device  3300 . First electronic device  3300  can include first magnet  3310 , pliable surface  3312 , housing portions  3320  and  3322 , shield  3340 , and return plate  3350 . In this figure, first magnet  3310  is not attracted to a second magnet, and therefore shield  3340  is magnetically attached or attracted to return plate  3350 . In this position, pliable surface  3312  can be relaxed. Pliable surface  3312  can be formed of an elastomer, silicon rubber open cell foam, silicon rubber, polyurethane foam, or other foam or other compressible material. 
     In  FIG.  33 B , second electronic device  3360  has been brought into the proximity of first electronic device  3300 . Second magnet  3370  can attract first magnet  3310 , thereby causing shield  3340  and return plate  3350  to separate from each other. First magnet  3310  can stretch pliable surface  3312  towards second electronic device  3360 , thereby allowing first magnet  3310  of first electronic device  3300  to move towards housing  3380  of second electronic device  3360 . Second magnet  3370  can be held in place in second electronic device  3360  by housing  3390  or other structure. As second electronic device  3360  is removed from first electronic device  3300 , first magnet  3310  and shield  3340  can be magnetically attracted to return plate  3350  as shown in  FIG.  33 A . 
       FIGS.  34 - 36    illustrate a moving magnetic structure according to an embodiment of the present invention. In this example, first electronic device  3400  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  3410  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  34   , first magnet  3410  and shield  3440  can be magnetically attracted or attached to return plate  3450  in first electronic device  3400 . First electronic device  3400  can be at least partially housed in device enclosure  3420 . In  FIG.  35   , housing  3480  of second electronic device  3460  can move laterally across a surface of device enclosure  3420  of first electronic device  3400  in a direction  3485 . Second magnet  3470  in second electronic device  3460  can begin to attract first magnet  3410  in first electronic device  3400 . This magnetic attraction  3415  can cause first magnet  3410  and shield  3440  to pull away from return plate  3450  by overcoming the magnetic attraction  3445  between shield  3440  and return plate  3450 . In  FIG.  36   , second magnet  3470  in second electronic device  3460  has become aligned with first magnet  3410  in first electronic device  3400 . First magnet  3410  and shield  3440  have pulled away from return plate  3450  thereby reducing the magnetic attraction  3445 . First magnet  3410  has moved nearby or adjacent to device enclosure  3420 , thereby increasing the magnetic attraction  3415  to second magnet  3470  in second electronic device  3460 . 
     As shown in  FIGS.  34 - 36   , the magnetic attraction between first magnet  3410  in first electronic device  3400  and the second magnet  3470  in the second electronic device  3460  can increase when first magnet  3410  and shield  3440  pull away from return plate  3450 . This is shown graphically in the following figures. 
       FIG.  37    illustrates a normal force between a first magnet in first electronic device and a second magnet in a second electronic device as a function of a lateral offset between them. As shown in  FIGS.  34 - 36   , with a large offset between first magnet  3410  and second magnet  3670 , first magnet  3410  and shield  3440  can remain attached to return plate  3450  in first electronic device  3400  and the magnetic attraction  3415  can be minimal. The shear force necessary to overcome this magnetic attraction is illustrated here as curve  3710 . As shown in  FIG.  35   , as the offset or lateral distance between first magnet  3410  and second magnet  3470  decreases, first magnet  3410  and shield  3440  can pull away or separate from return plate  3450 , thereby increasing the magnetic attraction  3415  between first magnet  3410  and second magnet  3470 . This is illustrated here as discontinuity  3720 . As shown in  FIG.  36   , as first magnet  3410  and second magnet  3470  come into alignment, the magnetic attraction  3415  increases along curve  3730  to a maximum  3740 . The difference between curve  3710  and curve  3730  can show the increase in magnetic attraction between a phone or other electronic device, such as second electronic device  3460  and an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention) or wireless charging device, such as first electronic device  3400 , that results from first magnet  3410  being able to move axially. It should also be noted that in this example first magnet  3410  does not move in a lateral direction, though in other examples it is capable of such movement. Where first magnet  3410  is capable of moving in a lateral direction, curve  3730  can have a flattened peak from an offset of zero to an offset that can be overcome by a range of possible lateral movement of first magnet  3410 . 
       FIG.  38    illustrates a shear force between a first magnet in a first electronic device and a second magnet in a second electronic device as a function of a lateral offset between them. With no offset between first magnet  3410  and second magnet  3460 , there it is no shear force to move second magnet  3470  relative to first magnet  3410 , as shown in  FIG.  34   . As the offset is increased, the shear force, that is the force attempting to realign the magnets, can increase along curve  3840 . At discontinuity  3810 , first magnet  3410  and shield  3440  can return to return plate  3450  (as shown in  FIGS.  34 - 36   ), thereby decreasing the magnetic shear force to point  3820 . The magnetic shear force can continue to drop off along curve  3830  as the offset increases. The difference between curve  3830  and curve  3840  can show the increase in magnetic attraction between a phone or other electronic device, such as second electronic device  3460  and an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention) or wireless charging device, such as first electronic device  3400 , that results from first magnet  3410  being able to move axially. It should also be noted that in this example first magnet  3410  does not move in a lateral direction, though in other examples it is capable of such movement. Where first magnet  3410  is capable of moving in a lateral direction, curve  3830  can remain at zero until the lateral movement of the second magnet  3470  overcomes the range of possible lateral movement of first magnet  3410 . 
     In these and other embodiments of the present invention, it can be desirable to further increase this shear force. Accordingly, embodiments of the present invention can provide various high friction or high stiction surfaces, suction cups, pins, or other structures to increase this shear force. Examples are shown in the following figures. 
       FIGS.  39 A and  39 B  illustrate a moving magnet in conjunction with a high friction or high stiction surface according to an embodiment of the present invention. In this example, first electronic device  3900  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  3910  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  39 A , first magnet  3910  and shield  3940  can be magnetically attracted or attached to return plate  3950  in first electronic device  3900 . First electronic device  3900  can be housed in device enclosure  3920 . Some or all of a surface of device enclosure  3920  can have a coating, layer, or other structure  3922 . Structure  3922  can provide a high friction or high stiction surface. In  FIG.  39 B , first magnet  3910  and shield  3940  can be attracted to a second magnet (not shown) in a second electronic device (not shown.) As before, the separation of first magnet  3910  and shield  3940  from return plate  3950  can provide an increased amount of magnetic flux to hold the second electronic device in place relative to first electronic device  3900 . Structure  3922  can increase the friction or stiction between first electronic device  3900  and the second electronic device in a lateral or shear direction. Structure  3922  can also increase the stiction between first electronic device  3900  and the second electronic device in a normal direction. 
       FIGS.  40 A and  40 B  illustrate a moving magnet in conjunction with a high friction or high stiction surface according to an embodiment of the present invention. In this example, first electronic device  4000  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  4010  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  40 A , first magnet  4010  and shield  4040  can be magnetically attracted or attached to return plate  4050  in first electronic device  4000 . First electronic device  4000  can be housed in device enclosure  4020 . Some or all of a surface of device enclosure  4020  can have a coating, layer, or other structure  4022 , in this example over first magnet  4010 . Structure  4022  can provide a high friction or high stiction surface. In  FIG.  40 B , first magnet  4010  and shield  4040  can be attracted to a second magnet (not shown) in a second electronic device (not shown.) This can cause first magnet  4010  and shield  4040  to separate from return plate  3950 , thereby deforming structure  4022 , which can be pliable or compliant. As before, first magnet  4010  can provide an increased amount of magnetic flux to hold the second electronic device in place relative to first electronic device  4000 . Structure  4022  can increase the friction or stiction between first electronic device  4000  and the second electronic device in a lateral or shear direction. Structure  4022  can also increase the stiction between first electronic device  4000  and the second electronic device in a normal direction. 
       FIGS.  41 A and  41 B  illustrate a moving magnet in conjunction with a high friction surface according to an embodiment of the present invention. In this example, first electronic device  4100  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  4110  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  41 A , first magnet  4110  and shield  4140  can be magnetically attracted or attached to return plate  4150  in first electronic device  4100 . First electronic device  4100  can be housed in device enclosure  4120 . Some or all of a surface of device enclosure  4120  can have a coating, layer, or other structure  4122 , in this example over a top surface of first electronic device  4100 . Structure  4122  can provide a high friction or high stiction surface. In  FIG.  41 B , first magnet  4110  and shield  4140  can be attracted to a second magnet (not shown) in a second electronic device (not shown.) The separation of first magnet  4110  and shield  4140  from return plate  4150  can push the top surface formed by structure  4122  upward where it can engage the second electronic device with a high-friction surface. As before, first magnet  4110  can provide an increased amount of magnetic flux to hold the second electronic device in place relative to first electronic device  4100 . Structure  4122  can increase the friction or stiction between first electronic device  4100  and the second electronic device in a lateral or shear direction. Structure  4122  can also increase the stiction between first electronic device  4100  and the second electronic device in a normal direction. 
       FIGS.  42 A and  42 B  illustrate another moving magnet in conjunction with a high friction or high stiction surface according to an embodiment of the present invention. In this example, first electronic device  4200  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  4210  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  42 A , first magnet  4210  and first return plate  4250  can be fixed in place in device enclosure  4220  of first electronic device  4200 . Some or all of a surface of device enclosure  4220  can have a coating, layer, or other structure  4222 . Structure  4222  can provide a high friction or high stiction surface. First electronic device  4200  can further include a moving second magnet  4291  and second shield  4292 , which can be attached to sliding mechanism  4290 . In  FIG.  42 B , as a second electronic device (not shown) comes into contact with first electronic device  4200 , sliding mechanism  4290  can be depressed, thereby moving second magnet  4291  away from second shield  4292  and the top surface of device enclosure  4220 . The polarity of second magnet  4291  can be in opposition to, or the opposite of, the polarity of first magnet  4210 , such that the net magnetic flux at a top surface of device enclosure  4220  is increased as sliding mechanism  4290  is depressed. Structure  4222  can increase the friction or stiction between first electronic device  4200  and the second electronic device in a lateral or shear direction. Structure  4222  can also increase the stiction between first electronic device  4200  and the second electronic device in a normal direction. 
       FIG.  43    illustrates a cutaway side view of another moving magnet structure according to an embodiment of the present invention. In this example, moving magnets can be incorporated with inductive charging, near field communication complements, or other electronic circuits or components in an electronic device. First electronic device  4300  can be, or can be a part of, attachment device  100 , attachment device  300 , attachment device  500 , a charging puck, card reader, or other electronic device. Moving first magnets  4210  (which can be any of the annular magnets shown above), shields  4240 , and return plates  4250  can be housed in device enclosure  4220  of first electronic device  4200 . Return plates  4250  can be attached to beams  4270 . Beams  4270  can be anchored to device enclosure  4220  at points  4274 . Beams  4270  can have tips  4272  extending above a top surface of device enclosure  4220 . A high friction or high stiction structure  4222  can be included over all or a portion of a top surface of first electronic device  4200 . 
       FIG.  44    is a partially transparent view of the moving magnet structure of  FIG.  43   . First electronic device  4300  can be housed in device enclosure  4320 . As before, first electronic device  4300  can include inductive charging, near field communication complements, or other electronic circuits for components  4378 . Return plates  4350  (shown in  FIG.  43   ) can be attached to beams  4370 . 
       FIG.  45    is another cutaway side view of the electronic device of  FIG.  43   . First electronic device  4300  can be housed in device enclosure  4320 . As before, first electronic device  4300  can include inductive charging, near field communication components, or other electronic circuits for components  4378 . Return plates  4350  can be attached to beams  4370 . First magnets  4310  and shield  4340  can be attracted or attached to return plate  4350 . A high friction or high stiction structure  4322  can cover some or all of a top surface of first electronic device  4300 . Beams  4370  can be attached to return plates  4350 , can be anchored at points  4374 , and can have a tip  4372  extending above top surface of device enclosure  4320 . 
       FIGS.  46  and  47    illustrate the electronic device of  FIG.  43    as it engages with a second electronic device. In  FIG.  46   , second electronic device  4380  can include second magnets  4390 . Second electronic device  4380  can engage with first electronic device  4300 . First electronic device  4300  can include first magnets  4310 , shields  4340 , and return plates  4350 . Return plates  4350  can be attached to beams  4370 . Beams  4370  can include tips  4372  which can extend above a top surface of device enclosure  4320 . Tips  4372  can prevent second electronic device  4380  from engaging with the high friction or high stiction structure  4322  of first electronic device  4300  until the second electronic device  4380  is aligned, or nearly aligned, with first electronic device  4300 . Beams  4370  can be attached at points  4374  to device enclosure  4320 . First electronic device  4300  can include components  4378 . 
     In  FIG.  47   , second electronic device  4380  can be aligned with the first electronic device  4300 . When this occurs, first magnets  4310  and shields  4340  can detach from return plates  4350 . This can increase magnetic flux between second magnets  4390  in second electronic device  4380  and first magnets  4310  and first electronic device  4300 . Tips  4372  can become depressed into device enclosure  4320  due to this increase magnetic attraction, thereby further pushing return plates  4350  away from shields  4340 . High friction or high stiction structure  4322  can engage with second electronic device  4380  to increase the shear force necessary for a detachment of second electronic device  4380  from first electronic device  4300 . Structure  4322  can also increase the stiction between first electronic device  4300  and the second electronic device in a normal direction. 
     In these and other embodiments of the present invention, various structures can be used to constrain movement of magnets in an electronic device. Examples are shown in the following figures. 
       FIGS.  48 A and  48 B  illustrate structures for constraining motions of magnets in an electronic device according to an embodiment of the present invention. In this example, first electronic device  4800  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  4810  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  48 A , magnet  4810 , shield  4840 , and structure  4870  can be housed by device enclosure  4820  in electronic device  4800 . Structure  4870  can include notch  4872 , which can accept tab  4824 . In  FIG.  48 B , magnet  4810  has moved, taking along with it shield  4840  and structure  4870 . Notch  4872  accepts tab  4824  as shield  4840  detaches from return plate  4850 . This can constrain the motion of magnets  4810  in electronic device  4800 . Electronic device  4800  can include a top device enclosure portion  4822 . Tab  4824  can be formed as part of or separate from top device enclosure portion  4822 . 
       FIGS.  49 A and  49 B  illustrate structures for constraining motions of magnets in an electronic device according to an embodiment of the present invention. In this example, first electronic device  4800  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  4810  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  49 A , magnet  4910 , shield  4940 , and return plate  4950  can be housed in device enclosure  4920  of electronic device  4900 . Top device enclosure portion  4922  can include guide  4924 . Guide  4924  can constrain motion of magnet  4910  in electronic device  4900 . In  FIG.  49 B , magnet  4910  and shield  4940  have detached from return plate  4950  and have been guided into position by guide  4924 . Guide  4924  can include one or more chamfered edges  4925 . Again, guide  4924  can be formed along with or separate from top device enclosure portion  4922  of electronic device  4900 . 
       FIGS.  50 A and  50 B  illustrate structures for constraining motions of magnets in an electronic device according to an embodiment of the present invention. In this example, first electronic device  5000  can be an attachment device (such as attachment device  100 , attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention), a wireless charging device, or other device having a magnet  5010  (which can be, e.g., any of the annular or other magnetic alignment components such as the magnet arrays and alignment magnets described above). In  FIG.  50 A , magnet  5010 , shield  5040 , and return plate  5050  can be housed in device enclosure  5020  of electronic device  5000 . Magnet  5010  and shield  5040  can be supported by structure  5070 . Structure  5070  can be attached to anchor  5074  through actuators  5072 . Actuators  5072  can have hinges  5073  and  5075  at each end to allow structure  5070  to move relative to anchor  5074 . Anchor  5074  can be attached to, or formed as either part of, top device enclosure portion  5022  or device enclosure  5020 . In  FIG.  50 B , magnet  5010  and shield  5040  have detached from return plate  5050 . Actuators  5072  have changed positions but continued to connect structure  5070  to anchor  5074 . Anchor  5074  can be attached to, or formed as either part of, top device enclosure portion  5022  or device enclosure  5020 . 
     For various applications, it may be desirable to enable a device having a magnetic alignment component to identify other devices that are brought into alignment. In some embodiments where the devices support a wireless charging standard that defines a communication protocol between devices, the devices can use that protocol to communicate. For example, the Qi standard for wireless power transfer defines a communication protocol that enables a power-receiving device (i.e., a device that has an inductive coil to receive power transferred wirelessly) to communicate information to a power-transmitting device (i.e., a device that has an inductive coil to generate time-varying magnetic fields to transfer power wirelessly to another device) via a modulation scheme in the inductive coils. The Qi communication protocol or similar protocols can be used to communicate information such as device identification or charging status or requests to increase or decrease power transfer from the power-receiving device to the power-transmitting device. 
     In some embodiments, a separate communication subsystem, such as a Near-Field Communication (NFC) subsystem can be provided to enable additional communication between devices. For example, each device that has an annular magnetic alignment component can also have an NFC coil that can be disposed inside and concentric with the annular magnetic alignment component. Where the device also has an inductive charging coil (which can be a transmitter coil or a receiver coil), the NFC coil can be disposed in a gap between the inductive charging coil and an annular magnetic alignment component. In some embodiments, the NFC coils can be used to allow a portable electronic device to identify other devices, such as a wireless charging device and/or an auxiliary device, when the respective magnetic alignment components of the devices are brought into alignment. For example, the NFC coil of a power-receiving device can be coupled to an NFC reader circuit while the NFC coil of a power-transmitting device or an accessory device is coupled to an NFC tag circuit. When devices are brought into proximity, the NFC reader circuit of the power-receiving device can be activated to read the NFC tag of the power-transmitting device and/or the accessory device. In this manner, the power-receiving device can obtain information (e.g., device identification) from the power-transmitting device and/or the accessory device. 
     In some embodiments, an NFC reader in a portable electronic device can be triggered by detecting a change in the DC (or static) magnetic field generated by the magnetic alignment component of the portable electronic device that corresponds to a change expected when another device with a complementary magnetic alignment component is brought into alignment. When the expected change is detected, the NFC reader can be activated to read an NFC tag in the other device, assuming the other device is present. 
     In some embodiments, an NFC tag may be located in a device that includes a wireless charger and an annular alignment structure. The NFC tag can be positioned and configured such that when the wireless charger device is aligned with a portable device having a complementary annular alignment structure and an NFC reader, the NFC tag is readable by the NFC reader of the portable electronic device. 
       FIG.  51    shows an exploded view of a wireless charger device  5102  incorporating an NFC tag according to some embodiments, and  FIG.  52    shows a partial cross-section view of wireless charger device  5102  according to some embodiments. As shown in  FIG.  51   , wireless charger device  5102  can include an enclosure  5104 , which can be made of plastic or metal (e.g., aluminum), and a charging surface  5106 , which can be made of silicone, plastic, glass, or other material that is permeable to AC and DC magnetic fields. Charging surface  5106  can be shaped to fit within a circular opening  5103  at the top of enclosure  5104 . 
     A wireless transmitter coil assembly  5111  can be disposed within enclosure  5104 . Wireless transmitter coil assembly  5111  can include a wireless transmitter coil  5112  for inductive power transfer to another device as well as AC magnetic and/or electric shield(s)  5113  disposed around some or all surfaces of wireless transmitter coil  5112 . Control circuitry  5114  (which can include, e.g., a logic board and/or power circuitry) to control wireless transmitter coil  5112  can be disposed in the center of coil  5112  and/or underneath coil  5112 . In some embodiments, control circuitry  5114  can operate wireless transmitter coil  5112  in accordance with a wireless charging protocol such as the Qi protocol or other protocols. 
     A primary annular magnetic alignment component  5116  can surround wireless transmitter coil assembly  5111 . Primary annular magnetic alignment component  5116  can include a number of arcuate magnet sections arranged in an annular configuration as shown. Each arcuate magnet section can include an inner arcuate region having a magnetic polarity oriented in a first axial direction, an outer arcuate region having a magnetic polarity oriented in a second axial direction opposite the first axial direction, and a central arcuate region that is not magnetically polarized. In some embodiments, the diameter and thickness of primary annular magnetic alignment component  5116  is chosen such that arcuate magnet sections of primary annular magnetic alignment component  5116  fit under a lip  5109  at the top surface of enclosure  5104 , as best seen in  FIG.  52   . For instance, each arcuate magnet section can be inserted into position under lip  5109 , either before or after magnetizing the inner and outer regions. In some embodiments, primary annular magnetic alignment component  5116  can have a gap  5136  between two adjacent arcuate magnet sections. Gap  5136  can be aligned with an opening  5107  in a side surface of enclosure  5104  to allow external wires to be connected to wireless transmitter coil  5112  and/or control circuitry  5114 . 
     A support ring subassembly  5140  can include an annular frame  5142  that extends in the axial direction and a friction pad  5144  at the top edge of frame  5142 . Friction pad  5144  can be made of a material such as silicone or thermoplastic elastomers (TPE) such as thermoplastic urethane (TPU) and can provide support and protection for charging surface  5106 . Frame  5142  can be made of a material such as polycarbonate (PC), glass-fiber reinforced polycarbonate (GFPC), or glass-fiber reinforced polyamide (GFPA). Frame  5142  can have an NFC coil  5164  disposed thereon. For example, NFC coil  5164  can be a four-turn or five-turn solenoidal coil made of copper wire or other conductive wire that is wound onto frame  5142 . In some embodiments, NFC coil  5164  can be electrically connected to NFC tag circuitry (not shown) that can be disposed on frame  5142 . The relevant design principles of NFC circuits are well understood in the art and a detailed description is omitted. Frame  5142  can be inserted into a gap region  5117  between primary annular magnetic alignment component  5116  and wireless transmitter coil assembly  5111 . In some embodiments, gap region  5117  is shielded by AC shield  5113  from AC electromagnetic fields generated in wireless transmitter coil  5112  and is also shielded from DC magnetic fields of primary annular magnetic alignment component  5116  by the closed-loop configuration of the arcuate magnet sections. 
       FIG.  53    shows a flow diagram of a process  5300  that can be implemented in portable electronic device  5004  according to some embodiments. In some embodiments, process  5300  can be performed iteratively while portable electronic device  5004  is powered on. At block  5302 , process  5300  can determine a baseline magnetic field, e.g., using magnetometer  5080 . At block  5304 , process  5300  can continue to monitor signals from magnetometer  5080  until a change in magnetic field is detected. At block  5306 , process  5300  can determine whether the change in magnetic field matches a magnitude and direction of change associated with alignment of a complementary magnetic alignment component. If not, then the baseline magnetic field can be updated at block  5302 . If, at block  5306 , the change in magnetic field matches a magnitude and direction of change associated with alignment of a complementary alignment component, then at block  5308 , process  5300  can activate the NFC reader circuitry associated with NFC coil  5060  to read an NFC tag of an aligned device. At block  5310 , process  5300  can receive identification information read from the NFC tag. At block  5312 , process  5300  can modify a behavior of portable electronic device  5004  based on the identification information, for example, generating a color wash effect as described above. After block  5312 , process  5300  can optionally return to block  5302  to provide continuous monitoring of magnetometer  5080 . It should be understood that process  5300  is illustrative and that other processes may be performed in addition to or instead of process  5300 . 
       FIG.  54    is a block diagram illustrating an exemplary wireless charging system including electronic device  5414  and attachment device  500  (which can instead be attachment device  300 , attachment device  500 , or other attachment device according to an embodiment of the present invention) that can be aligned together via a magnetic alignment system  5408 . Magnetic alignment system  5408  can include a primary alignment component  5410  within attachment device  500  and a secondary alignment component  5412  within portable electronic device  5414 . The electronic device can include a computing system  5416  coupled to a memory bank  5418 . Computing system  5416  can include control circuitry configured to execute instructions stored in memory bank  5418  for performing a plurality of functions for operating the electronic device. The control circuitry can include one or more suitable computing devices, such as microprocessors, computer processing units (CPUs), graphics processing units (GPUs), field programmable gate arrays (FPGAs), and the like. 
     Computing system  5416  can also be coupled to a user interface system  5420 , a communication system  5422 , and a sensor system  5424  for enabling the electronic device to perform one or more functions. For instance, user interface system  5420  can include a display, speaker, microphone, actuator for enabling haptic feedback, and one or more input devices such as a button, switch, capacitive screen for enabling the display to be touch sensitive, and the like. Communication system  5422  can include wireless telecommunication components, Bluetooth components, and/or wireless fidelity (Wi-Fi) components for enabling the electronic device to make phone calls, interact with wireless accessories, and access the Internet. In some embodiments, communication system  5422  can also include NFC components  560  that is formed as part of a proximity detector for identifying attachment device  500 , as discussed above. Sensor system  5424  can include light sensors, accelerometers, gyroscopes, temperature sensors, and any other type of sensor that can measure a parameter of an external entity and/or environment. 
     These electrical components require a power source to operate. Accordingly, the electronic device also includes a battery  5426  for discharging stored energy to power the electrical components of the electronic device. To replenish the energy discharged to power the electrical components, the electronic device includes charging circuitry  5428  and an inductive coil  5430  for receiving power from attachment device  500  coupled to an external power source  5432 . 
     Attachment device  500  can include a transmitter coil  5434  for generating time-varying magnetic flux capable of generating a corresponding current in coil  5430  of the electronic device. The generated current can be utilized by charging circuitry  5428  to charge battery  5426 . Attachment device  500  can further include a computing system  5436  coupled to a communication system  5440  and wireless charging circuitry  5442 . Computing system  5436  can include any suitable control circuitry discussed herein configured to control the functionality of attachment device  500 , such as to control wireless charging circuitry  5442  to use power received from power source  5432  to generate time-varying magnetic flux to charge the electronic device. 
     While these and other embodiments of the present invention can be particularly well-suited to securing a phone in place relative to an interior of a vehicle (or other mobile locations, such a train, plane, bicycle, rover, motorcycle, jet ski, or other conveyance), other devices, such as tablet computers, laptop computers, desktop computers, all-in-one computers, cell phones, storage devices, wearable-computing devices, portable media players, navigation systems, monitors, adapters, and others can be secured in place in a vehicle or other conveyance, or other fixed or mobile location. 
     In these and other embodiments of the present invention, portions of the attachment devices can be conductive. These conductive portions, such as a shield, return plate, backplate, and other portions can be formed using stamping, forging, metal-injection molding, 3-D printing, CNC or other machining, or other manufacturing process. They can be formed of stainless steel, aluminum, or other material. 
     In these and other embodiments of the present invention, portions of the attachment devices can be nonconductive. These nonconductive portions, such as a housing for the attachment portion, stalk, a contacting surface, and other nonconductive portions, can be formed using injection or other molding, 3-D printing, machining, or other manufacturing process. They can be formed of silicon or silicone, rubber, hard rubber, plastic, nylon, liquid-crystal polymers (LCPs), or other nonconductive material or combination of materials. 
     It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     The above description of embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described, and many modifications and variations are possible in light of the teaching above. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Thus, it will be appreciated that the invention is intended to cover all modifications and equivalents within the scope of the following claims.

Metadata:
Filing Date: 20210805
Publication Date: 20240716
Grant Date: 20240716
Priority Date: 20200805
Inventors: KARANIKOS, DEMETRIOS B.
SANGHVI, VARUN K.
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/90", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/366", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/0252", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/90", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0044", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/0044", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/90", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0044", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 80115363