PATENT DOCUMENT

Publication Number: US-11867352-B2
Application Number: US-202117317725-A
Country: US
Kind Code: B2

Title: Adapter for charging and stabilizing cameras

Abstract:
Adapters that can mount phones or other electronic devices on camera stabilizers, where the adapters are portable, can capable of charging, and can allow cameras on the phones to be easily leveled or adjusted to any orientation. An adapter can include a base portion having an opening, where a fastener in the opening can attach the adapter to a camera stabilizer, as well as an upright portion having an enclosure and a contacting surface. The enclosure can house a first magnet array for magnetically attracting a second magnet array in a phone, such that the phone can be readily mounted to a camera stabilizer. The enclosure can further house near-field communication circuits and components for identification. The upright portion and base portion can be connected by a fixed right angle or by a hinge, which can allow the adapter to fold into a more convenient form.

Claims:
What is claimed is: 
     
       1. An adapter comprising:
 a lateral base portion, wherein the base portion includes an opening, wherein the opening is configured to provide an attachment to a camera stabilizer; and 
 an upright portion comprising:
 a contacting surface for contacting an electronic device; and 
 an enclosure, the enclosure forming a ring around the contacting surface, the enclosure further forming sides and a back of the upright portion, 
 
 wherein the enclosure and the contacting surface enclose:
 an attachment structure to attach the electronic device to the adapter; and 
 charging components to charge the electronic device. 
 
 
     
     
       2. The adapter of  claim 1  wherein the upright portion is attached to the base portion with a right-angle portion such that the upright portion is orthogonal to the base portion. 
     
     
       3. The adapter of  claim 1  wherein the upright portion is attached to the base portion with a hinge such that the upright portion is rotatable relative to the base portion. 
     
     
       4. The adapter of  claim 1  further comprising a near-field communication transmitter. 
     
     
       5. The adapter of  claim 1  wherein the contacting surface provides a high-friction surface. 
     
     
       6. The adapter of  claim 5  wherein the surface of the contacting surface is adhesive. 
     
     
       7. The adapter of  claim 1  wherein the attachment structure comprises a magnet array. 
     
     
       8. The adapter of  claim 7  wherein the camera stabilizer is one of a tripod or a gimbal. 
     
     
       9. An adapter comprising:
 a base portion forming a base; and 
 an upright portion attached to the base portion with a hinge such that the base portion is rotatable relative to the upright portion, the upright portion comprising: 
 a contacting surface for contacting an electronic device; and 
 an enclosure, the enclosure around the contacting surface, the enclosure further forming sides and a back of the upright portion, 
 wherein the enclosure and the contacting surface enclose an attachment feature. 
 
     
     
       10. The adapter of  claim 9  wherein the upright portion includes a recess and the base portion is rotatable about the hinge such that the base portion fits in the recess. 
     
     
       11. The adapter of  claim 9  wherein the base portion includes a receptacle for receiving power and the enclosure and the contacting surface further enclose a charging coil. 
     
     
       12. The adapter of  claim 9  further comprising a near-field communication transmitter. 
     
     
       13. The adapter of  claim 9  wherein the contacting surface provides a high-friction surface. 
     
     
       14. The adapter of  claim 13  wherein the surface of the contacting surface is adhesive. 
     
     
       15. An adapter comprising:
 a lateral base portion; and 
 an upright portion attached to the base portion with a right-angle portion such that the upright portion is orthogonal to the base portion, the upright portion comprising:
 a contacting surface for contacting an electronic device; and 
 an enclosure, the enclosure around the contacting surface, the enclosure further forming sides and a back of the upright portion, 
 
 wherein the enclosure and the contacting surface enclose an attachment feature. 
 
     
     
       16. The adapter of  claim 15  wherein the enclosure for the upright portion is formed with an enclosure for the base portion and the right-angle portion as a single piece. 
     
     
       17. The adapter of  claim 15  wherein the attachment feature comprises a magnet array and the enclosure and the contacting surface further enclose a charging coil. 
     
     
       18. The adapter of  claim 15  further comprising a near-field communication transmitter. 
     
     
       19. The adapter of  claim 15  wherein the contacting surface provides a high-friction surface. 
     
     
       20. The adapter of  claim 19  wherein the surface of the contacting surface is adhesive.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of and priority to U.S. provisional application No. 63/081,844, filed Sep. 22, 2020, and 63/061,458, filed Aug. 5, 2020, which are incorporated by reference. 
    
    
     BACKGROUND 
     The capabilities of some electronic devices to perform non-traditional tasks has been growing at an increasing rate. Examples include watches that can track a runner&#39;s course and tablet computers that can provide turn-by-turn directions. Other examples include the video and still cameras that are provided on some phones. 
     New phones can include multiple cameras, where each camera has a different focal length or range of focal lengths and can optimized for specific types of images, such as portraits, group photos, or low-light photography. Specialized software and processors can help to improve the quality of these various types of images. Some of these cameras have such a high quality that they are replacing traditional single-lens reflex (SLR) and other cameras in many applications. 
     The adoption of phone cameras into these non-traditional uses has been slowed by a lack of enabling infrastructure. While there are vast numbers and types of camera stabilizers such as tripods, gimbals, and other devices for SLR cameras, the same does not exist for cameras on phones. 
     Accordingly, it can be desirable to provide adapters, mounts, and other devices to allow existing camera stabilizers to be used with cameras on phones. Also, since many photographers have camera bags and camera backpacks that are already loaded with equipment, it can be desirable that these adapters be small and compact. 
     In many circumstances, these phone cameras might be used for very long periods. They can also be used in power-intensive applications such as recording video. As such, it can also be desirable that a phone be able to be charged while the phones are mated to the adapters. Since these adapters might be used in various environments, it can also be desirable that the cameras on the phones be readily placed in various orientations or positions to provide flexibility for a user. 
     Thus, what is needed are adapters that can mount phones on camera stabilizers, where the adapters are highly portable and are useful in a number of situations and environments. 
     SUMMARY 
     Accordingly, embodiments of the present invention can provide adapters that can attach phones or other electronic devices to camera stabilizers, where the adapters are highly portable and are useful in a number of situations and environments. An illustrative embodiment of the present invention can provide an adapter having a lateral base portion having an opening. The opening can be used to fasten the adapter to a camera stabilizer such as a tripod, gimbal, pier, drone, or other device. The adapter can further have an upright portion, where the upright portion can include a contacting surface for physically contacting a phone. The contacting surface can have a high friction or high stiction surface to increase friction between the adapter and phone. This can increase a shear force needed to remove the phone from the adapter. The upright portion and the base portion can be connected through a fixed right angle. The upright portion and the base portion can alternatively be connected though a hinge. This can allow the upright portion to be folded closed, that is, next to the base portion for a more compact arrangement, or opened to an angle, such as a right-angle. This can allow the adapter to more adroitly fit in a user&#39;s likely already crowded bag or backpack. 
     The upright portion can further include an enclosure forming a ring around the contacting surface, as well as sides and a back of the upright portion. The enclosure can house or support an attachment feature to attach a phone or other electronic device to the adapter. The attachment feature can be a magnet, a plurality of magnets, or a first magnet array. The attachment feature, such as a first magnet array, can magnetically attract a second attachment feature, such as a second magnet array, in a phone or other electronic device. The first magnet array can be positioned behind the ring around the contacting surface or elsewhere in the enclosure. The first magnet array can be fixed in place in the enclosure. Alternatively, when the phone or other electronic device is in proximity to the adapter, the first magnet array can move within the enclosure towards the contacting surface to increase the magnetic attraction between the phone and the adapter. This can increase a normal force necessary to remove the phone from the adapter. The first magnet array can have a shape and arrangement such that the phone (and its camera) can be freely rotatable about an axis of connection with the adapter. This can help in leveling and otherwise positioning the camera in a portrait or landscape mode, as well as at any angle between them. The adapter can further include additional magnets separate from the first magnet array to improve the alignment of the phone to the adapter at a specific position, such as in a portrait, landscape, or other orientation. The magnetic attachment between the electronic device and the adapter can provide a fast and simple way of attaching a phone or other electronic device to a camera stabilizer. 
     The enclosure can further include charging components such as an inductive coil for providing inductive charging and transmitting data to the phone and for receiving data from the phone. The enclosure can further include shielding to magnetically isolate the inductive coil from the first magnet array. This isolation can improve inductive coupling from the inductive coil to a corresponding coil of a power receiving phone or electronic device. Control electronics that receive an input power supply and generate alternating currents through the inductive coil can also be included in the enclosure. These alternating currents can generate a time-varying magnetic flux in the corresponding coil. The time-varying magnetic flux can generate currents in the corresponding coil that can be used to charge a battery in the phone. The time-varying magnetic flux can be modulated to transmit data to the phone. The control electronics can also sense currents induced in the coil in the adapter by the phone or other electronic device. The control circuitry can further read data transmitted by the phone using these induced currents. The data can include device identification for the phone, charge status, charging level requests, and other information. 
     Power and data can be received by an adapter through a cable. Data can also be transmitted by the adapter over this cable. The cable can be tethered to circuitry and components in the adapter, or the cable can include a connector insert that can be inserted into a connector receptacle in the adapter. The connector receptacle or other cable connection can be located in the base portion, upright portion, right-angle portion, or other portion of the adapter. The cable can provide a connection to the adapter from a power converting brick, battery pack, electronic device, or other power supply source. The cable can also provide data to be transmitted from the adapter to a phone or other external electronic device. 
     The adapter enclosure can further house near-field communication circuitry and components, such as a near-field communication tag and capacitors. This near-field communication circuitry in the adapter can be or include a near-field communication transmitter that can communicate with a near-field communication receiver in the phone or other electronic device. The near-field communication circuitry and components can allow a phone or other electronic device to detect an attached adapter for a camera stabilizer. This recognition can prompt the phone to perform one or more activities. For example, the phone can launch one or more camera applications, where the launched applications can be predetermined by the adapter manufacturer, software developers, the user, or others. A leveling application can automatically start on the phone after the recognition of an adapter attachment. Other devices, such as a watch that can be used to control the phone&#39;s camera, can be prompted to run specific software by the phone or the adapter. Further, specific applications for specific camera stabilizers can be launched. Other functions, such as notifications, can be disabled or silenced. The near-field communication circuitry and components can further provide identification and authentication information to the phone. This can be used by the phone in determining whether it is safe to be charged by the adapter, and at what power level the adapter can charge the phone. 
     While embodiments of the present invention are well-suited to providing adapters between phones and camera stabilizers, they can be used in other types of applications as well. For example, embodiments of the present invention can provide adapters that can be used between tablet computers and camera stabilizers, 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 adapter for a camera stabilizer according to an embodiment of the present invention; 
         FIG.  2    illustrates an adapter for a camera stabilizer according to an embodiment of the present invention; 
         FIG.  3    illustrates the backside of the adapter of  FIG.  2   ; 
         FIG.  4 A  and  FIG.  4 B  illustrate an adapter for a camera stabilizer according to an embodiment of the present invention; 
         FIG.  5    illustrates a cutaway side view of the adapter of  FIG.  4 A ; 
         FIG.  6    is an exploded view of the adapter of  FIG.  4 A ; 
         FIG.  7    illustrates an operation of an electronic device that is mated with an adapter according to an embodiment of the present invention; 
         FIG.  8    shows a simplified representation of a wireless charging system incorporating a magnetic alignment system according to some embodiments; 
         FIG.  9 A  shows a perspective view of a magnetic alignment system according to some embodiments, and  FIG.  9 B  shows a cross-section through the magnetic alignment system of  FIG.  9 A ; 
         FIG.  10 A  shows a perspective view of a magnetic alignment system according to some embodiments, and  FIG.  10 B  shows a cross-section through the magnetic alignment system of  FIG.  10 A ; 
         FIG.  11    shows a simplified top-down view of a secondary alignment component according to some embodiments; 
         FIG.  12 A  shows a perspective view of a magnetic alignment system according to some embodiments, and  FIG.  12 B  shows an axial cross-section view through a portion of the system of  FIG.  12 A , while  FIGS.  12 C through  12 E  show examples of arcuate magnets with radial magnetic orientation according to some embodiments; 
         FIGS.  13 A and  13 B  show graphs of force profiles for different magnetic alignment systems, according to some embodiments; 
         FIG.  14    shows a simplified top-down view of a secondary alignment component according to some embodiments; 
         FIG.  15 A  shows a perspective view of a magnetic alignment system according to some embodiments, and  FIGS.  15 B and  15 C  show axial cross-section views through different portions of the system of  FIG.  15 A ; 
         FIGS.  16 A and  16 B  show simplified top-down views of secondary alignment components according to various embodiments; 
         FIG.  17    shows a simplified top-down view of a secondary alignment component according to some embodiments; 
         FIG.  18    shows an example of a portable electronic device and an accessory incorporating a magnetic alignment system with an annular alignment component and a rotational alignment component according to some embodiments; 
         FIGS.  19 A and  19 B  show an example of rotational alignment according to some embodiments; 
         FIGS.  20 A and  20 B  show a perspective view and a top view of a rotational alignment component having a “z-pole” configuration according to some embodiments; 
         FIGS.  21 A through  21 F  show rotational alignment components according to some embodiments; 
         FIG.  22    shows graphs of torque as a function of angular rotation for magnetic alignment systems having rotational alignment components according to various embodiments; 
         FIG.  23    shows a portable electronic device having an alignment system with multiple rotational alignment components according to some embodiments; 
         FIGS.  24 A through  24 C  illustrate moving magnets according to an embodiment of the present invention; 
         FIGS.  25 A and  25 B  illustrate a moving magnetic structure according to an embodiment of the present invention; 
         FIGS.  26 A and  26 B  illustrate a moving magnetic structure according to an embodiment of the present invention; 
         FIG.  27    through  FIG.  29    illustrate a moving magnetic structure according to an embodiment of the present invention; 
         FIG.  30    illustrates a normal force between a first magnet in a first electronic device and a second magnet in a second electronic device; 
         FIG.  31    illustrates a shear force between a first magnet in a first electronic device and a second magnet in a second electronic device; 
         FIGS.  32 A and  32 B  illustrate a moving magnet in conjunction with a high friction surface according to an embodiment of the present invention; 
         FIGS.  33 A and  33 B  illustrate a moving magnet in conjunction with a high friction surface according to an embodiment of the present invention; 
         FIGS.  34 A and  34 B  illustrate a moving magnet in conjunction with a high friction surface according to an embodiment of the present invention; 
         FIGS.  35 A and  35 B  illustrate another moving magnet in conjunction with a high friction surface according to an embodiment of the present invention; 
         FIG.  36    illustrates a cutaway side view of another moving magnet structure according to an embodiment of the present invention; 
         FIG.  37    is a partially transparent view of the moving magnet structure of  FIG.  36   ; 
         FIG.  38    is another cutaway side view of the electronic device of  FIG.  36   ; 
         FIGS.  39  and  40    illustrate the electronic device of  FIG.  36    as it engages with a second electronic device; 
         FIGS.  41 A and  41 B  illustrate structures for constraining motions of magnets in an electronic device according to an embodiment of the present invention; 
         FIGS.  42 A and  42 B  illustrate structures for constraining motions of magnets in an electronic device according to an embodiment of the present invention; 
         FIGS.  43 A and  43 B  illustrate structures for constraining motions of magnets an electronic device according to an embodiment of the present invention; 
         FIG.  44    shows an exploded view of a wireless charger device incorporating an NFC tag circuit according to some embodiments; 
         FIG.  45    shows a partial cross-section view of wireless charger device according to some embodiments; and 
         FIG.  46    shows a flow diagram of a process that can be implemented in a portable electronic device according to some embodiments. 
     
    
    
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
       FIG.  1    illustrates an adapter for a camera stabilizer according to an embodiment of the present invention. Adapter  100  can be used to secure electronic device  180  to camera stabilizer  190 . In this particular example, electronic device  180  can be a phone, though electronic device  180  can instead be a tablet computer, wearable computing device, camera (such as an SLR or a camera colloquially referred to as a point and shoot camera), or other electronic or mechanical device. Electronic device  180  can include one or more lenses, flash units, Light Detection and Ranging (LiDAR) Scanners or other components  182 . Camera stabilizer  190  is shown as a tripod, though camera stabilizer  190  can instead be a gimbal, pier, drone, or other camera stabilizer or other control or positioning device. 
     In these and other embodiments of the present invention, adapter  100  can be a passive adapter to mechanically secure electronic device  180  to camera stabilizer  190 . In these and other embodiments the present invention, adapter  100  can instead be a powered adapter. When adapter  100  is a powered adapter, adapter  100  can include a connector receptacle  450  (shown in  FIG.  4   ) for a cable (not shown.) A power converter (not shown) can further be included in adapter  100  or can be separate from adapter  100  and attached to camera stabilizer  190  or elsewhere. 
     Photographers often have a large number of devices, lenses, batteries, and other components. They can often carry these components in a camera bag, in which space can be at a premium. Accordingly, it can be desirable that adapter  100  have a small form factor. It can also be desirable that adapter  100  fold into a compact shape for storage and transport. An example is shown in the following figure. 
       FIG.  2    illustrates an adapter for a camera stabilizer according to an embodiment of the present invention. Adapter  110  can be used as adapter  100  in  FIG.  1   , or as an adapter in other systems according to an embodiment of the present invention. Adapter  110  can include base portion  230  attached to upright portion  200  at hinge  240 . Base portion  230  can include a hole or opening  232  for accepting a fastener (not shown) to secure adapter  110  to camera stabilizer  190  (shown in  FIG.  1   .) Upright portion  200  can include enclosure  210 . Enclosure  210  can form ring  212  around contacting surface  220 . It should be noted that while ring  212  is shown in this example as being roughly circular, in other embodiments of the present invention ring  212  can have an oval, square, or other shape. Contacting surface  220  can physically contact electronic device  180 . Contacting surface  220  can be a high friction or high stiction surface that increases a shear force needed to remove electronic device  180  from adapter  110 . Contacting surface  220  can also be at least somewhat adhesive. This can increase a normal force needed to remove electronic device  180  from adapter  110 . Contacting surface  220 , 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. Enclosure  210 , and the other enclosures 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. 
     Enclosure  210  and contacting surface  220  can enclose or house one or more attachment features that can be used to secure electronic device  180  to adapter  100 . For example, enclosure  210  and contacting surface  220  can enclose one or more magnets  500 , as shown in  FIG.  5   . These one or more magnets  500  can attract corresponding magnets (shown as secondary alignment components  818  in  FIG.  8   ) in electronic device  180  (shown in  FIG.  1   .) This magnetic attraction can secure electronic device  180  to adapter  110  in a direction normal to, or orthogonal to, contacting surface  220 . The magnetic connection between electronic device  180  and adapter  110  can provide a fast and simple way of attaching a phone or other electronic device  180  to a camera stabilizer  190  (shown in  FIG.  1   .) 
     Accordingly, it can be desirable for adapter  110  to provide a strong magnetic force to hold electronic device  180  securely in place to avoid an inadvertent disconnection. However, when no electronic device  180  is mated with adapter  110 , magnets  500  can cause undesirable effects. For example, magnets  500  can inadvertently demagnetize information, such as information on credit cards or transit passes. Accordingly, a magnetic field provided by magnets  500  can be increased when adapter  110  is, or is about to be, mated with electronic device  180 . 
     This magnetic field can be increased in various ways to more securely attach electronic device  180  to adapter  100 . For example, the magnetic field can be generated by an electromagnet (not shown) used along with, or in place of, magnets  500 . Current through the electromagnet can be increase increased during mating of adapter  110  to electronic device  180  to increase the magnetic attraction provided by the electromagnet. Also or instead, magnets  500  can move from a first position to a second position when adapter  110  is, or is about to be, mated with electronic device  180 . Examples of magnets  500  that either move or are fixed (nonmoving) are shown below. 
       FIG.  3    illustrates the backside of the adapter of  FIG.  2   . Adapter  110  can include a base portion  230  and an upright portion  200 . Base portion  230  can be joined to upright portion  200  at hinge  240 . Hinge  240  can allow base portion  230  to move through positions  300  for storage. Base portion  230  can fit in recess  202  in a back side of upright portion  200 . Since base portion  230  fits in recess  202 , base portion  230  does not contribute to the overall size of adapter  110  when folded for transport, thereby saving space. Base portion  230  can include opening  232 . A fastener (not shown) can pass through opening  232  to secure adapter  110  to camera stabilizer  190 , as shown in  FIG.  1   . In these and other embodiments of the present invention, opening  232  can be replace by a fastener attached to base portion  230 , where the fastener is used to attach adapter  110  to a camera stabilizer. 
       FIGS.  4 A and  4 B  illustrate an adapter for a camera stabilizer according to an embodiment of the present invention. In  FIG.  4 A , adapter  120  can be used as adapter  100  in  FIG.  1   , or as an adapter in other systems according to an embodiment of the present invention. Adapter  120  can include base portion  430  and upright portion  400 . Base portion  430  can be joined to upright portion  400  by right-angle portion  440 . Base portion  430  can include opening  432  for accepting a fastener (not shown) to secure adapter  120  to camera stabilizer  190  (shown in  FIG.  1   .) Base portion  430  can include opening  434  in a side for connector receptacle  450 . Connector receptacle  450  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  450  can accept a connector insert of a cable (not shown) through which power and data can be received by adapter  120  and data can be provided by adapter  120 . Upright portion  400  can include enclosure  410  and contacting surface  420 . Enclosure  410  can provide ring  412  around contacting surface  420 . It should be noted that while ring  412  is shown in this example as being roughly circular, in other embodiments of the present invention ring  412  can have an oval, square, or other shape. Contacting surface  420  can physically contact electronic device  180  (shown in  FIG.  1   .) Contacting surface  420  can be a high friction or high stiction surface that increases a shear force needed to remove electronic device  180  from adapter  120 . Contacting surface  420  can also be at least somewhat adhesive. This can increase a normal force needed to remove electronic device  180  from adapter  120 . Contacting surface  420  can be formed of an elastomer, plastic, PVC plastic, rubber, silicon rubber, urethane, polyurethane, nitrile, neoprene, silicone, or other material. 
     In  FIG.  4 B , adapter  120  can include base portion  430  and upright portion  400 . Base portion  430  can be joined to upright portion  400  by right-angle portion  440 . Base portion  430  can include opening  434  in a side for connector receptacle  450 . Connector receptacle  450  can accept a connector insert of a cable (not shown) through which power and data can be received by adapter  120  and data can be provided by adapter  120 . 
       FIG.  5    illustrates a cutaway side view of the adapter of  FIG.  4 A . Adapter  120  can include base portion  430  having opening  432 , as well as upright portion  400 . Base portion  430  can be joined to upright portion  400  by right-angle portion  440 . Upright portion  400  can be housed by enclosure  410  and contacting surface  420 . 
     Enclosure  410  and contacting surface  420  can house magnets  500 . Magnets  500  can be fixed in place relative to enclosure  410 . Alternatively, magnets  500  can move between at least a first position and a second position. For example, when adapter  120  is not mated with electronic device  180  (shown in  FIG.  1   ), magnets  500  can be in the first or recessed position away from ring  412  and contacting surface  420 . This can reduce a stray magnetic field at contacting surface  420 , which can help to protect magnetically stored information, such as information stored on a user&#39;s credit cards or transit passes. As electronic device  180  is brought into the proximity of adapter  120 , magnets (shown as secondary alignment components  818  in  FIG.  8   ) in the electronic device  180  can attract magnets  500  in adapter  120 . This attraction can cause the movement of magnets  500  to the second position, which can be closer to a surface of ring  412  and contacting surface  420 . This change in position can increase the magnetic field between magnets  500  and magnets in electronic device  180 , thereby securing electronic device  180  in place against contacting surface  420  of adapter  120 . Examples of magnets  500  that are fixed as well as examples of magnets  500  that are capable of moving are shown in figures below. 
     Electronic device  180  can often operate in a high power consumption mode when it is attached to adapter  120 . For example, electronic device  180  can include a flash. Electronic device  180  can operate in a video mode, which can involve writing large volumes of data to a memory. These and other activities can consume a fair amount of power from a battery internal to electronic device  180 . 
     Accordingly, in these and other embodiments of the present invention, it can be desirable for adapter  120  to be able to charge electronic device  180 . For this reason, enclosure  410  and contacting surface  420  can further house coil  570  and control electronics  590 . Coil  570  can be shielded by shield  580 . Shield  580  can be formed of a material that has high magnetic permeability, such as stainless steel. Shield  580  can shield magnets  500  from coil  570 . Shield  580  can further improve the inductive coupling between coil  570  and a corresponding coil (shown as inductive coil  810  in  FIG.  8   ) in electronic device  180 . Control electronics  590  can provide an alternating current to coil  570 . The resulting current in coil  570  can generate a time-varying magnetic flux that can induce sympathetic currents in a corresponding coil in electronic device  180 . Control electronics (not shown) in electronic device  180  can use these induced currents to charge an internal battery. 
     Coil  570  and control electronics  590  can also allow adapter  120  to receive data from electronic device  180 . For example, control circuits in electronic device  180  can provide current to the coil in electronic device  180 . These currents can generate sympathetic currents in coil  570  in adapter  120 . These sympathetic currents in coil  570  can be read by control electronics  590  in adapter  120 . These currents can be modulated in amplitude, phase, or frequency to convey data from electronic device  180  to adapter  120 . This data can include charge status, identification, authorization, information regarding power receiving capability, update information, or other types of information or data. For example, electronic device  180  can inform adapter  120  of the charging status and power receiving capability of electronic device  180 . This data can be used by adapter  120 . This data can also be provided to an external device by control electronics  590  through flexible circuit board  442 , board  610 , and a cable (not shown.) For example, image and sound captured by electronic device  180  can be provided to an external device (not shown), such as a monitor, through adapter  120 . 
     Similarly, data can be sent from adapter  120  to electronic device  180 . Data can be generated by adapter  120  or received by adapter  120  through connector receptacle  450 . Control electronics  590  can receive data (for example from board  610  through flexible circuit board  442 ) and generate currents in coil  570 . The currents in coil  570  can be modulated in amplitude, phase, or frequency to convey data from adapter  120  to electronic device  180 . This data can include identification, authorization, information regarding power providing capability, or other types of information or data. The currents in coil  570  can generate induced currents in the corresponding coil in electronic device  180 , which can be read by the control electronics in electronic device  180 . 
     Power and data can be received at board  610  through a cable attached at connector receptacle  450  (shown in  FIG.  4 A ) on adapter  120 . Alternatively, board  610  can receive power and data through a cable tethered to adapter  120 , for example though opening  434  (shown in  FIG.  4 A ) in base portion  430 . Board  610  can provide power and data to control electronics  590  via flexible circuit board  442  or other conduit in right-angle portion  440 . 
     When an electronic device  180  is attached to adapter  120 , it can be useful for electronic device  180  to determine that it is attached to an adapter for a camera stabilizer, and in response, to enter a camera mode. For example, electronic device  180  can activate camera hardware and applications, such as filtering, leveling, and other applications. It can also be useful for certain applications to be deactivated. For example, it can be desirable to turn off notifications or other applications that could otherwise be distracting to a user. 
     Accordingly, enclosure  410  and contacting surface  420  of adapter  120  can further enclose near-field communications components  560 . Near-field communications components  560  can include a tag, capacitor, and support ring  562 . The near-field communications components  560  can form a near-field communications transmitter that can communicate with a near-field communications receiver (not shown) in electronic device  180 . A magnetometer or other sensor (not shown) in electronic device  180  can sense magnets  500  in adapter  120 . In response, electronic device  180  can activate internal near-field communications components and circuitry (not shown) to generate a radio-frequency field. Near-field communications transmitter components  560  in adapter  120  can receive this radio-frequency field and use it to power a tag. The tag can then modulate this radio-frequency field. The modulated radio-frequency field can be read by the near field communications receiver components and circuitry in electronic device  180 . Electronic device  180  can then determine that it is mounted on adapter  120 . Once this determination is been made, electronic device  180  can enter a camera mode and turn on and turn off applications as described above. 
       FIG.  6    is an exploded view of the adapter of  FIG.  4 A . Adapter  120  can include base portion  430  attached to upright portion  400  by right-angle portion  440 . Upright portion  400  can include enclosure  410  and contacting surface  420 . Magnets  500  can be housed by enclosure  410  and contacting surface  420 . Magnets  500  can encircle coil  570 . Near-field communications transmitter components  560  can be supported by support ring  562 . Control electronics  590  can be located in a center of coil  570 . Coil  570  can be shielded by ferrite or shield  580  and e-shield  620 . Leads  572  of coil  570  can pass through slot  582  in ferrite or shield  580  to attach to pads  592  of control electronics  590 . Magnets  500  can be positioned behind ring  412  of enclosure  410 . 
     Base portion  430  can include board  610 , which can be connected to control electronics  590  through flexible circuit board  442  (shown in  FIG.  5   .) Board  610  can support connector receptacle  450 , which can be available at opening  434 . Board  610  can be protected by bottom plate  438 , which can be attached to base portion  430  by fasteners  439 . A fastener (not shown) can pass through opening  432  in base portion  430  to secure adapter  120  to camera stabilizer  190  (shown in  FIG.  1   .) In these and other embodiments of the present invention, opening  432  can be replace by a fastener attached to base portion  430 , where the fastener is used to attach adapter  120  to a camera stabilizer. 
     In these and other embodiments of the present invention, these structures can be formed of various materials in various ways. Contacting surface  420 , 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. Enclosure  410  and bottom plate  438 , and the other enclosures, bottom 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. Ferrite or shield  580  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. E-shield  620  can be formed of a layer of copper or other conductive material to intercept electric fields between coil  570  and a corresponding coil (not shown) in electronic device  180  (shown in  FIG.  1   ), and can have a low magnetic permeability to pass magnetic fields between coil  570  and the corresponding coil. E-shield  620  can include breaks to prevent the formation of eddy currents. Board  610  can be formed of FR-4 or other material. 
     Some or all of the circuitry and components shown in  FIG.  6    can be implemented in adapter  100 , adapter  110 , and adapter  120 . For example, each adapter  100 ,  110 , and  120  can include magnets  500  for attaching electronic device  180  (shown in  FIG.  1   ) to camera stabilizer  190 . Each adapter  100 ,  110 , and  120  can further include coil  570  and control electronics  590  for charging electronic device  180 . Each adapter  100 ,  110 , and  120  can further include near-field communications transmitter components  560  for identification purposes. Each of these and other circuits and components shown in  FIG.  6    can be included or omitted from adapters according to embodiments of the present invention, such as adapters  100 ,  110 , and  120 , and other circuits and components can be included. 
     These circuits and components can allow adapters  100 ,  110 , and  120  to provide power to electronic device  180 . They can also allow adapters  100 ,  110 , and  120  to receive data from electronic device  180 . They can also allow adapters  100 ,  110 , and  120  to provide data to electronic device  180 . They can also allow electronic device  180  to detect that electronic device  180  is attached to an adapter, such as adapter  100 ,  110 , or  120 . 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 being developed. 
     For example, power can be received by adapter  120  (or adapters  100  or  110 ) via a cable attached at opening  434 , for example at connector receptacle  450 . This received power can be an AC voltage that is converted to a DC voltage at board  610 , or it can be a DC voltage that is received by board  610 . Board  610  can provide power to control electronics  590  via flexible circuit board  442  or other conduit. Control electronics can provide an alternating current to coil  570 . This current can generate a time-varying magnetic flux that can induce currents in a corresponding coil in electronic device  180 . These induced currents can be used to charge a battery in electronic device  180 . 
     Data can be received by adapter  120  (or adapters  100  or  110 ) from electronic device  180 . For example, control electronics in electronic device  180  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 sympathetic current in coil  570 , from which data can be read by control electronics  590 . The read data can be used by the adapter, or sent to another electronic device via flexible circuit board  442  or other conduit, board  610 , connector receptacle  450 , and a cable. 
     Similarly, data can be transmitted by adapter  120  (or adapters  100  or  110 ) to electronic device  180 . Control electronics  590  can receive data, either from adapter  120  itself, or from an external source (not shown) via the cable, connector receptacle  450 , and flexible circuit board  442  or other conduit. Control electronics  590  can modulate a current provided to coil  570 . This current can be modulated in amplitude, phase, or frequency. The current can induce a current in the corresponding coil in electronic device  180 , from which the data can be read. 
     Electronic device  180  can detect that electronic device  180  is attached to an adapter, such as adapter  100 ,  110 , or  120 . A magnetometer or other sensor (not shown) in electronic device  180  can sense magnets  500  in adapter  120 . In response, electronic device  180  can activate internal near-field communications components and circuitry (not shown) to generate a radio-frequency field. Near-field communications transmitter components  560  in adapter  120  can receive this radio-frequency field and use it to power a tag. The tag can then modulate this radio-frequency field. The modulated radio-frequency field can be read by the near field communications components and circuitry in electronic device  180 . Electronic device  180  can then determine that it is mounted on adapter  120 . 
     Again, as electronic device  180  determines that it is attached to adapter  120 , electronic device  180  can enter a camera mode. Various applications can be turned on and off in this camera mode. An example is shown in the following figure. 
       FIG.  7    illustrates an operation of an electronic device that is mated with an adapter according to an embodiment of the present invention. In act  700 , an electronic device, such as electronic device  180  (shown in  FIG.  1   ) can be aligned with and attached to an adapter, such as adapter  120  in  FIG.  4 A . In act  710 , adapter  120  (or adapter  100  or  110 ) can use its coil  570  to ping electronic device  180 . Adapter can analyze the impedance seen by the coil in generating the ping and determine the presence of electronic device  180 . If electronic device  180  is unpowered, for example a battery in electronic device  180  is fully discharged, adapter  120  can begin to provide power to charge electronic device  180 . If electronic device  180  is powered, electronic device  180  can detect this ping and determine whether it needs to be charged in act  720 . If electronic device  180  does need to be charged, then in act  730 , electronic device  180  can instruct adapter  120  to begin charging electronic device  180 , and adapter  120  in response can begin to charge electronic device  180 . If electronic device  180  does not need to be charged, adapter  120  does not charge electronic device  180 . 
     Whether or not electronic device  180  needs to be charged, electronic device  180  can detect magnets  500  in adapter  120  and in response can generate a near-field signal in act  740 . Electronic device  180  can then receive data in response from near-field communications transmitter components  560 , which can include a tag and capacitors, in adapter  120 . Electronic device  180  can then determine that it is mounted on adapter  120 . 
     In response to this detection, electronic device  180  can perform such activities as turning on camera hardware and starting up a leveling user interface in act  750 . In act  760 , camera software can be activated on the electronic device. Camera software can also be activated on other associated devices, for example a watch (not shown) that is paired with electronic device  180 , external lighting (not shown), external camera triggers (not shown), a drone (not shown), or other electronic device. In act  770 , camera stabilizer specific software can be activated. Other applications or software programs can be deactivated in act  780 . For example, notifications and other applications that can cause distractions for a user can be disabled in act  780 . The specific applications that are started and stopped in response to a determination that the electronic device  180  is mounted on adapter  120  can be programmed, controlled, or adjusted by manufacturers, users, or other third parties. 
     The various electronic functions performed by adapter  120  can be performed by circuits and components in either or both control electronics  590  and board  610 . Typically, control electronics  590  can receive and provide currents in coil  570 , while board  610  can receive power and data from an external source. 
     Again, magnets  500  can be fixed in place, or they can be movable between a first position and a second position. Examples of fixed magnets that can be used for magnets  500  are shown in the following figures. For example, magnets  500  can be any of the primary magnetic alignment components such as primary magnetic alignment component  816 . As another example, coil  570  can be inductive coil  812  or any of the other coils shown herein. Adapter  100  and the other adapters can be implemented using the details of wireless charger device  802  and the other wireless chargers below. 
     Described herein are various embodiments of magnetic alignment systems and components thereof. A magnetic alignment system can include annular alignment components, where each annular alignment component can comprise a ring of magnets (or a single annular magnet) 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. Magnetic alignment components can be incorporated into a variety of devices, and a magnetic alignment component in one device can attract another device having a complementary magnetic alignment component into a desired alignment and/or hold the other device in a desired alignment. (Devices aligned by a magnetic alignment system can be said to be “attached” to each other.) 
     For purposes of the present description, a number of different categories of devices can be distinguished. As used herein, a “portable electronic device” refers generally to any electronic device that is portable and that consumes power and provides at least some interaction with the user. Examples of portable electronic devices include: smart phones and other mobile phones (more generally, phones); tablet computers; laptop computers; wearable devices (e.g., smart watches, headphones, earbuds); and any other electronic device that a user may carry or wear. Other portable electronic devices can include robotic devices, remote-controlled devices, personal-care appliances, and so on. 
     An “accessory device” (or “accessory”) refers generally to an adapter, such as adapter  100  (shown in  FIG.  1   ), adapter  110  (shown in  FIG.  2   ), or adapter  120  (shown in  FIG.  4   ), or other adapter consistent with an embodiment of the present invention, or other device that is useful in connection with a portable electronic device to enhance the functionality and/or esthetics of the portable electronic device. Many categories of accessories may incorporate magnetic alignment. For example, one category of accessories includes wireless charger accessories. As used herein, a “wireless charger accessory” (or “wireless charger device” or just “wireless charger”) is an accessory that can provide power to a portable electronic device using wireless power transfer techniques. A “battery pack” (or “external battery”) is a type of wireless charger accessory that incorporates a battery to store charge that can be transferred to the portable electronic device. In some embodiments, a battery pack may also receive power wirelessly from another wireless charger accessory. Wireless charger accessories may also be referred to as “active” accessories, in reference to their ability to provide and/or receive power. Other accessories are “passive accessories” that do not provide or receive power. For example, some passive accessories are “cases” that can cover one or more surfaces of the portable electronic device to provide protection (e.g., against damage caused by impact of the portable electronic device with other objects), esthetic enhancements (e.g., decorative colors or the like), and/or functional enhancements (e.g., cases that incorporate storage pockets, batteries, card readers, or sensors of various types). Cases can have a variety of form factors. For example, a “tray” can refer to a case that has a rear panel covering the back surface of the portable electronic device and side surfaces to secure the portable electronic device in the tray while leaving the front surface (which may include a display) exposed. A “sleeve” can refer to a case that has front and back panels with an open end (or “throat”) into which a portable electronic device can be inserted so that the front and back surfaces of the device are covered; in some instances, the front panel of a sleeve can include a window through which a portion (or all) of a display of the portable electronic device is visible. A “folio” can refer to a case that has a retention portion that covers at least the back surface (and sometimes also one or more side surfaces) of the portable electronic device and a cover that can be closed to cover the display or opened to expose the display. It should be understood that not all cases are passive accessories. For example, a “battery case” can incorporate a battery pack in addition to protective and/or esthetic features; a battery case can be shaped generally as a tray, sleeve, or folio. Other examples of active cases can include cases that incorporate card readers, sensors, batteries, or other electronic components that enhance functionality of a portable electronic device. 
     In the present description, a distinction is sometimes made between a “charge-through accessory,” which is an accessory that can be positioned between a portable electronic device and a wireless charger device without interfering with wireless power transfer between the wireless charger device and the portable electronic device, and a “terminal accessory,” which is an accessory that is not a charge-through accessory. A wireless charging accessory is typically a terminal accessory, but not all terminal accessories provide wireless charging of a portable electronic device. For example some terminal accessories can be “mounting” accessories that are designed to hold the portable electronic device in a particular position. Examples of mounting include tripods, docking stations, other stands, or mounts that can hold a portable electronic device in a desired position and/or orientation (which might or might not be adjustable). Such accessories might or might not incorporate wireless charging capability. 
     According to embodiments described herein, a portable electronic device and an accessory device can include complementary magnetic alignment components that facilitate alignment of the accessory device with the portable electronic device and/or attachment of the accessory device to the portable electronic device. The magnetic alignment components can include annular magnetic alignment components that, in some embodiments, can surround inductive charging transmitter and receiver coils. In the nomenclature used herein, a “primary” annular magnetic alignment component refers to an annular magnetic alignment component used in a wireless charger device or other terminal accessory. A “secondary” annular magnetic alignment component refers to an annular magnetic alignment component used in a portable electronic device. An “auxiliary” annular magnetic alignment component refers to an annular magnetic alignment component used in a charge-through accessory. (In this disclosure, adjectives such as “annular,” “magnetic,” “primary,” “secondary” and “auxiliary” may be omitted when the context is clear.) 
     In some embodiments, a magnetic alignment system can also include a rotational magnetic alignment component that facilitates aligning two devices in a preferred rotational orientation. A rotational magnetic alignment component can include, for example, one or more magnets disposed outboard of an annular alignment component. It should be understood that any device that has an annular alignment component might or might not also have a rotational alignment component, and rotational alignment components may be categorized as primary, secondary, or auxiliary depending on the type of device. 
     In some embodiments, a magnetic alignment system can also include a near-field communication (NFC) coil and supporting circuitry to allow devices to identify themselves to each other using an NFC protocol. An NFC coil in a particular device can be an annular coil that is disposed inboard of the annular alignment component or outboard of the annular alignment component. For example, in a device that has an annular alignment component surrounding an inductive charging coil, the NFC coil can be disposed in an annular gap between the inductive charging coil and the annular alignment component. It should be understood that an NFC component is optional in the context of providing magnetic alignment. 
       FIG.  8    shows a simplified representation of a wireless charging system  800  incorporating a magnetic alignment system  806  according to some embodiments. A portable electronic device  804  is positioned on a charging surface  808  of a wireless charger device  802 . Portable electronic device  804  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 charger device  802  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 charger device  802  can be any of the adapters shown above, a wireless charging mat, puck, docking station, or the like. Wireless charger device  802  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  804  and wireless charger device  802  can include inductive coils  810  and  812 , respectively, which can operate to transfer power between them. For example, inductive coil  812  can be a transmitter coil that generates a time-varying magnetic flux  814 , and inductive coil  810  can be a receiver coil in which an electric current is induced in response to time-varying magnetic flux  814 . The received electric current can be used to charge a battery of portable electronic device  804 , to provide operating power to a component of portable electronic device  804 , 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  812  and  810 . According to some embodiments, magnetic alignment system  806  can provide such alignment. In the example shown in  FIG.  8   , magnetic alignment system  806  includes a primary magnetic alignment component  816  disposed within or on a surface of wireless charger device  802  and a secondary magnetic alignment component  818  disposed within or on a surface of portable electronic device  804 . Primary and secondary alignment components  816  and  818  are configured to magnetically attract one another into an aligned position in which inductive coils  810  and  812  are aligned with one another to provide efficient 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. 
       FIG.  9 A  shows a perspective view of a magnetic alignment system  900  according to some embodiments, and  FIG.  9 B  shows a cross-section through magnetic alignment system  900  across the cut plane indicated in  FIG.  9 A . Magnetic alignment system  900  can be an implementation of magnetic alignment system  806  of  FIG.  8   . In magnetic alignment system  900 , 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  901  of magnetic alignment system  900 , and a transverse plane (also referred to as a “lateral” or “x” or “y” direction) is defined to be normal to axis  901 . The term “proximal side” or “proximal surface” is used herein to refer to a side or surface of one alignment component that is oriented toward the other alignment component when the magnetic alignment system is aligned, and the term “distal side” or “distal surface” is used to refer to a side or surface opposite the proximal side or surface. (The terms “top” and “bottom” may be used in reference to a particular view shown in a drawing but have no other significance.) 
     As shown in  FIG.  9 A , magnetic alignment system  900  can include a primary alignment component  916  (which can be an implementation of primary alignment component  816  of  FIG.  8   ) and a secondary alignment component  918  (which can be an implementation of secondary alignment component  818  of  FIG.  8   ). Primary alignment component  916  and secondary alignment component  918  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  916  and secondary alignment component  918  can each have an outer diameter of about 124 mm and a radial width of about 13 mm. The outer diameters and radial widths of primary alignment component  916  and secondary alignment component  918  need not be exactly equal. For instance, the radial width of secondary alignment component  918  can be slightly less than the radial width of primary alignment component  916  and/or the outer diameter of secondary alignment component  918  can also be slightly less than the radial width of primary alignment component  916  so that, when in alignment, the inner and outer sides of primary alignment component  916  extend beyond the corresponding inner and outer sides of secondary alignment component  918 . Thicknesses (or axial dimensions) of primary alignment component  916  and secondary alignment component  918  can also be chosen as desired. In some embodiments, primary alignment component  916  has a thickness of about 8.5 mm while secondary alignment component  918  has a thickness of about 0.37 mm. 
     Primary alignment component  916  can include a number of sectors, each of which can be formed of one or more primary arcuate magnets  926 , and secondary alignment component  918  can include a number of sectors, each of which can be formed of one or more secondary arcuate magnets  928 . In the example shown, the number of primary magnets  926  is equal to the number of secondary magnets  928 , and each sector includes exactly one magnet, but this is not required. Primary magnets  926  and secondary magnets  928  can have arcuate (or curved) shapes in the transverse plane such that when primary magnets  926  (or secondary magnets  928 ) are positioned adjacent to one another end-to-end, primary magnets  926  (or secondary magnets  928 ) form an annular structure as shown. In some embodiments, primary magnets  926  can be in contact with each other at interfaces  930 , and secondary magnets  928  can be in contact with each other at interfaces  932 . Alternatively, small gaps or spaces may separate adjacent primary magnets  926  or secondary magnets  928 , providing a greater degree of tolerance during manufacturing. 
     In some embodiments, primary alignment component  916  can also include an annular shield  914  (also referred to as a DC magnetic shield or DC shield) disposed on a distal surface of primary magnets  926 . In some embodiments, shield  914  can be formed as a single annular piece of material and adhered to primary magnets  926  to secure primary magnets  926  into position. Shield  914  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  916 , thereby protecting sensitive electronic components located beyond the distal side of primary alignment component  916  from magnetic interference. 
     Primary magnets  926  and secondary magnets  928  (and all other magnets described herein) 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. In some embodiments, the magnets can be plated with a thin layer (e.g., 14-13 μm) of NiCuNi or similar materials. Each primary magnet  926  and each secondary magnet  928  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  915 ,  917  in  FIG.  9 B . For example, each primary magnet  926  and each secondary magnet  928  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 or magnetized region.) In the example shown, primary magnet  926  has its north pole oriented toward the proximal surface and south pole oriented toward the distal surface while secondary magnet  928  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  926  has its south pole oriented toward the proximal surface and north pole oriented toward the distal surface while secondary magnet  928  has its north pole oriented toward the proximal surface and south pole oriented toward the distal surface. 
     As shown in  FIG.  9 B , the axial magnetic orientation of primary magnet  926  and secondary magnet  928  can generate magnetic fields  940  that exert an attractive force between primary magnet  926  and secondary magnet  928 , thereby facilitating alignment between respective electronic devices in which primary alignment component  916  and secondary alignment component  918  are disposed (e.g., as shown in  FIG.  8   ). While shield  914  can redirect some of magnetic fields  940  away from regions below primary magnet  926 , magnetic fields  940  may still propagate to regions laterally adjacent to primary magnet  926  and secondary magnet  928 . In some embodiments, the lateral propagation of magnetic fields  940  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 (or inboard) region of annular primary alignment component  916  (or secondary alignment component  918 ), leakage of magnetic fields  940  may saturate the ferrimagnetic shield, which can degrade wireless charging performance. 
     It will be appreciated that magnetic alignment system  900  is illustrative and that variations and modifications are possible. For instance, while primary alignment component  916  and secondary alignment component  918  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  916  and/or secondary alignment component  918  can each be formed of a single, monolithic annular magnet; however, segmenting magnetic alignment components  916  and  918  into arcuate magnets may improve manufacturing because (for some types of magnetic material) smaller arcuate segments may be less brittle than a single, monolithic annular magnet and less prone to yield loss due to physical stresses imposed on the magnetic material during manufacturing. 
     As noted above with reference to  FIG.  9 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 a “closed-loop” configuration that reduces magnetic field leakage. Examples will now be described. 
       FIG.  10 A  shows a perspective view of a magnetic alignment system  1000  according to some embodiments, and  FIG.  10 B  shows a cross-section through magnetic alignment system  1000  across the cut plane indicated in  FIG.  10 A . Magnetic alignment system  1000  can be an implementation of magnetic alignment system  806  of  FIG.  8   . In magnetic alignment system  1000 , the alignment components have magnetic components configured in a “closed loop” configuration as described below. 
     As shown in  FIG.  10 A , magnetic alignment system  1000  can include a primary alignment component  1016  (which can be an implementation of primary alignment component  816  of  FIG.  8   ) and a secondary alignment component  1018  (which can be an implementation of secondary alignment component  818  of  FIG.  8   ). Primary alignment component  1016  and secondary alignment component  1018  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  1016  and secondary alignment component  1018  can each have an outer diameter of about 124 mm and a radial width of about 13 mm. The outer diameters and radial widths of primary alignment component  1016  and secondary alignment component  1018  need not be exactly equal. For instance, the radial width of secondary alignment component  1018  can be slightly less than the radial width of primary alignment component  1016  and/or the outer diameter of secondary alignment component  1018  can also be slightly less than the radial width of primary alignment component  1016  so that, when in alignment, the inner and outer sides of primary alignment component  1016  extend beyond the corresponding inner and outer sides of secondary alignment component  1018 . Thicknesses (or axial dimensions) of primary alignment component  1016  and secondary alignment component  1018  can also be chosen as desired. In some embodiments, primary alignment component  1016  has a thickness of about 8.5 mm while secondary alignment component  1018  has a thickness of about 0.37 mm. 
     Primary alignment component  1016  can include a number of sectors, each of which can be formed of a number of primary magnets  1026 , and secondary alignment component  1018  can include a number of sectors, each of which can be formed of a number of secondary magnets  1028 . In the example shown, the number of primary magnets  1026  is equal to the number of secondary magnets  1028 , 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  1026  and secondary magnets  1028  can have arcuate (or curved) shapes in the transverse plane such that when primary magnets  1026  (or secondary magnets  1028 ) are positioned adjacent to one another end-to-end, primary magnets  1026  (or secondary magnets  1028 ) form an annular structure as shown. In some embodiments, primary magnets  1026  can be in contact with each other at interfaces  1030 , and secondary magnets  1028  can be in contact with each other at interfaces  1032 . Alternatively, small gaps or spaces may separate adjacent primary magnets  1026  or secondary magnets  1028 , providing a greater degree of tolerance during manufacturing. 
     In some embodiments, primary alignment component  1016  can also include an annular shield  1014  (also referred to as a DC magnetic shield or DC shield) disposed on a distal surface of primary magnets  1026 . In some embodiments, shield  1014  can be formed as a single annular piece of material and adhered to primary magnets  1026  to secure primary magnets  1026  into position. Shield  1014  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  1016 , thereby protecting sensitive electronic components located beyond the distal side of primary alignment component  1016  from magnetic interference. 
     Primary magnets  1026  and secondary magnets  1028  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  1028  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  1017  in  FIG.  10 B ). As described below, the magnetic orientation can be in a radial direction with respect to axis  1001  or another direction having a radial component in the transverse plane. Each primary magnet  1026  can include two magnetic regions having opposite magnetic orientations. For example, each primary magnet  1026  can include an inner arcuate magnetic region  1052  having a magnetic orientation in a first axial direction (as shown by polarity indicator  1053  in  FIG.  10 B ), an outer arcuate magnetic region  1054  having a magnetic orientation in a second axial direction opposite the first direction (as shown by polarity indicator  1055  in  FIG.  10 B ), and a central non-magnetized region  1056  that does not have a magnetic orientation. Central non-magnetized region  1056  can magnetically separate inner arcuate region  1052  from outer arcuate region  1054  by inhibiting magnetic fields from directly crossing through central region  1056 . 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  1028  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  1026  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  1026  can be a compound structure with two arcuate pieces of magnetic material providing inner arcuate magnetic region  1052  and outer arcuate magnetic region  1054 ; in such embodiments, central non-magnetized region  1056  can be formed of an arcuate piece of nonmagnetic (or demagnetized) material or formed as an air gap defined by sidewalls of inner arcuate magnetic region  1052  and outer arcuate magnetic region  1054 . DC shield  1014  can be formed of a material that has high magnetic permeability, such as stainless steel or low carbon steel, and can be plated, e.g., with 12-10 μm of matte Ni. Alternatively, DC shield  1014  can be formed of a magnetic material having a radial magnetic orientation (in the opposite direction of secondary magnets  1028 ). In some embodiments, DC shield  1014  can be omitted entirely. 
     As shown in  FIG.  10 B , the magnetic polarity of secondary magnet  1028  (shown by indicator  1017 ) can be oriented such that when primary alignment component  1016  and secondary alignment component  1018  are aligned, the south pole of secondary magnet  1028  is oriented toward the north pole of inner arcuate magnetic region  1052  (shown by indicator  1053 ) while the north pole of secondary magnet  1028  is oriented toward the south pole of outer arcuate magnetic region  1054  (shown by indicator  1055 ). Accordingly, the respective magnetic orientations of inner arcuate magnetic region  1052 , secondary magnet  1028  and outer arcuate magnetic region  1056  can generate magnetic fields  1040  that exert an attractive force between primary magnet  1026  and secondary magnet  1028 , thereby facilitating alignment between respective electronic devices in which primary alignment component  1016  and secondary alignment component  1018  are disposed (e.g., as shown in  FIG.  8   ). Shield  1014  can redirect some of magnetic fields  1040  away from regions below primary magnet  1026 . Further, the “closed-loop” magnetic field  1040  formed around central non-magnetized region  1056  can have tight and compact field lines that do not stray outside of primary and secondary magnets  1026  and  1028  as far as magnetic field  940  strays outside of primary and secondary magnets  926  and  928  in  FIG.  9 B . Thus, magnetically sensitive components can be placed relatively close to primary alignment component  1016  with reduced concern for stray magnetic fields. Accordingly, as compared to magnetic alignment system  900 , magnetic alignment system  1000  can help to reduce the overall size of a device in which primary alignment component  1016  is positioned and can also help reduce noise created by magnetic field  1040  in adjacent components or devices, such as an inductive receiver coil positioned inboard of secondary alignment component  1018 . 
     While each primary magnet  1026  includes two regions of opposite magnetic orientation, it should be understood that the two regions can but need not provide equal magnetic field strength. For example, outer arcuate magnetized region  1054  can be more strongly polarized than inner arcuate magnetized region  1052 . Depending on the particular implementation of primary magnets  1026 , various techniques can be used to create asymmetric polarization strength. For example, inner arcuate region  1052  and outer arcuate region  1054  can have different radial widths; increasing radial width of a magnetic region increases the field strength of that region due to increased volume of magnetic material. Where inner arcuate region  1052  and outer arcuate region  1054  are discrete magnets, magnets having different magnetic strength can be used. 
     In some embodiments, having an asymmetric polarization where outer arcuate region  1054  is more strongly polarized than inner arcuate region  1052  can create a flux “sinking” effect toward the outer pole. This effect can be desirable in various situations. For example, when primary magnet  1026  is disposed within a wireless charger device and the wireless charger device is used to charge a “legacy” portable electronic device that has an inductive receiver coil but does not have a secondary (or any) annular magnetic alignment component, the (DC) magnetic flux from the primary annular alignment component may enter a ferrite shield around the inductive receiver coil. The DC magnetic flux can contribute to saturating the ferrite shield and reducing charging performance. Providing a primary annular alignment component with a stronger field at the outer arcuate region than the inner arcuate region can help to draw DC magnetic flux away from the ferrite shield, which can improve charging performance when a wireless charger device having an annular magnetic alignment component is used to charge a portable electronic device that lacks an annular magnetic alignment component. 
     It will be appreciated that magnetic alignment system  1000  is illustrative and that variations and modifications are possible. For instance, while primary alignment component  1016  and secondary alignment component  1018  are each shown as being constructed of eight arcuate magnets, other embodiments may use a different number of magnets, such as 86 magnets, 88 magnets, 102 magnets, 106 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  1018  can be formed of a single, monolithic annular magnet. Similarly, primary alignment component  1016  can be formed of a single, monolithic annular piece of magnetic material with an appropriate magnetization pattern as described above, or primary alignment component  1016  can be formed of a monolithic inner annular magnet and a monolithic outer annular magnet, with an annular air gap or region of nonmagnetic 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  1000 , secondary alignment component  1018  can have a magnetic orientation with a radial component. For example, in some embodiments, secondary alignment component  1018  can have a magnetic polarity in a radial orientation.  FIG.  11    shows a simplified top-down view of a secondary alignment component  1118  according to some embodiments. Secondary alignment component  1118 , like secondary alignment component  1018 , can be formed of arcuate magnets  1128   a - h  having radial magnetic orientations as shown by magnetic polarity indicators  1117   a - h . In this example, each arcuate magnet  1128   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 arcuate magnet  1128   a - h  can be oriented toward the radially inward side while the south magnetic pole is oriented toward the radially outward side. 
       FIG.  12 A  shows a perspective view of a magnetic alignment system  1200  according to some embodiments. Magnetic alignment system  1200 , which can be an implementation of magnetic alignment system  1000 , includes a secondary alignment component  1218  having a radially outward magnetic orientation (e.g., as shown in  FIG.  11   ) and a complementary primary alignment component  1216 . In this example, magnetic alignment system  1200  includes a gap  1217  between two of the sectors; however, gap  1217  is optional and magnetic alignment system  1200  can be a complete annular structure. Also shown are components  1202 , which can include, for example an inductive coil assembly or other components located within the central region of primary magnetic alignment component  1216  or secondary magnetic alignment component  1218 . Magnetic alignment system  1200  can have a closed-loop configuration similar to magnetic alignment system  1000  (as shown in  FIG.  10 B ) and can include arcuate sectors  1201 , each of which can be made of one or more arcuate magnets. In some embodiments, the closed-loop configuration of magnetic alignment system  1200  can reduce or prevent magnetic field leakage that may affect components  1202 . 
       FIG.  12 B  shows an axial cross-section view through one of arcuate sectors  1201 . Arcuate sector  1201  includes a primary magnet  1226  and a secondary magnet  1228 . As shown by orientation indicator  1219 , secondary magnet  1228  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  1200 . Like primary magnets  1026  described above, primary magnet  1226  includes an inner arcuate magnetic region  1252 , an outer arcuate magnetic region  1254 , and a central non-magnetized region  1256  (which can include, e.g., an air gap or a region of nonmagnetic or non-magnetized material). Inner arcuate magnetic region  1252  has a magnetic polarity oriented axially such that the north magnetic pole is toward secondary magnet  1228 , as shown by indicator  1253 , while outer arcuate magnetic region  1254  has an opposite magnetic orientation, with the south magnetic pole oriented toward secondary magnet  1228 , as shown by indicator  1255 . As described above with reference to  FIG.  10 B , the arrangement of magnetic orientations shown in  FIG.  12 B  results in magnetic attraction between primary magnet  1226  and secondary magnet  1228 . In some embodiments, the magnetic polarities can be reversed such that the north magnetic pole of secondary magnet  1228  is oriented toward the radially inward side of magnetic alignment system  1200 , the north magnetic pole of outer arcuate region  1254  of primary magnet  1226  is oriented toward secondary magnet  1228 , and the north magnetic pole of inner arcuate region  1252  is oriented away from secondary magnet  1228 . 
     When primary alignment component  1216  and secondary alignment component  1218  are aligned, the radially symmetrical arrangement and directional equivalence of magnetic polarities of primary alignment component  1216  and secondary alignment component  1218  allow secondary alignment component  1218  to rotate freely (relative to primary alignment component  1216 ) 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.  12 C  shows a secondary arcuate magnet  1238  according to some embodiments. Secondary arcuate magnet  1238  has a purely radial magnetic orientation, as indicated by arrows  1239 . Each arrow  1239  is directed at the center of curvature of magnet  1238 ; if extended inward, arrows  1239  would converge at the center of curvature. However, achieving this purely radial magnetization requires that magnetic domains within magnet  1238  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.  12 C .  FIG.  12 D  shows a secondary arcuate magnet  1248  with pseudo-radial magnetic orientation according to some embodiments. Magnet  1248  has a magnetic orientation, shown by arrows  1249 , that is perpendicular to a baseline  1251  connecting the inner corners  1257 ,  1259  of arcuate magnet  1248 . If extended inward, arrows  1249  would not converge. Thus, neighboring magnetic domains in magnet  1248  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.  12 C .  FIG.  12 E  shows a secondary annular alignment component  1258  made up of magnets  1248  according to some embodiments. Magnetic orientation arrows  1249  have been extended to the center point  1261  of annular alignment component  1258 . As shown the magnetic field direction can be approximately radial, with the closeness of the approximation depending on the number of magnets  1248  and the inner radius of annular alignment component  1258 . In some embodiments, 18 magnets  1248  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  1218  (e.g., as shown in  FIG.  12 B ) provides a magnetic force profile between secondary alignment component  1218  and primary alignment component  1216  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  1218  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.  13 A and  13 B  show graphs of force profiles for different magnetic alignment systems, according to some embodiments. Specifically,  FIG.  13 A  shows a graph  1300  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  1300  has a horizontal axis representing displacement from a center of alignment, where 0 represents the aligned position and negative and positive values represent displacements from the aligned position in opposite directions (in arbitrary units), and a vertical axis showing the normal force (F NORMAL ) as a function of displacement in the lateral plane (also 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  1300  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  1301  (dot-dash line). A second type of magnetic alignment system uses annular alignment components with axial magnetic orientations, e.g., magnetic alignment system  900  of  FIGS.  9 A and  9 B ; a representative normal force profile for such an annular-axial magnetic alignment system is shown as line  1303  (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  1200  of  FIGS.  12 A and  12 B ); a representative normal force profile for a radially symmetric closed-loop magnetic alignment system is shown as line  1305  (solid line). 
     Similarly,  FIG.  13 B  shows a graph  1320  of lateral (shear) force in a transverse direction for different magnetic alignment systems. Graph  1320  has a horizontal axis representing lateral displacement in opposing directions from a center of alignment, using the same convention as graph  1300 , 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  1320  shows shear force profiles for the same three types of magnetic alignment systems as graph  1300 : a representative shear force profile for a central magnetic alignment system is shown as line  1321  (dot-dash line); a representative shear force profile for an annular-axial magnetic alignment system is shown as line  1323  (dashed line); and a representative normal force profile for a radially symmetric closed-loop magnetic alignment system is shown as line  1325  (solid line). 
     As shown in  FIG.  13 A , each type of magnetic alignment system achieves the strongest magnetic attraction in the axial direction (i.e., normal force) when the primary and secondary alignment components are in the aligned position ( 0  on the horizontal axis), as shown by respective peaks  1311 ,  1313 , and  1315 . 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  1200  of  FIG.  12   ) 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 and can help to hold devices in the aligned position, thereby can achieving 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 charger device within which the magnetic alignment system is implemented. 
     As shown in  FIG.  13 B , the strongest shear forces 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  1331   a - b ,  1333   a - b , and  1335   a - b . These shear forces act to urge the alignment components toward the aligned position. Similarly to the normal force, 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  1200  of  FIG.  12   ) 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 (sometimes described as a sensation of “snappiness”) to help the user identify when the two components are aligned. In addition, like the normal force, the 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 charger device within which the magnetic alignment system is implemented. 
     Depending on the particular configuration of magnets, various design choices can be used to increase the sensation of snappiness for a closed-loop magnetic alignment system. For example, reducing the amount of magnetic material in the devices in areas near the magnetic alignment components—e.g., by using less material or by increasing the distance between the magnetic alignment component and the other magnetic material—can reduce stray fields and increase the perceived “snapping” effect of the magnetic alignment components. As another example, increasing the magnetic-field strength of the alignment magnets (e.g., by increasing the amount of material) can increase both shear and normal forces. As yet another example, the widths of the magnetized regions in the primary annular alignment component (and/or the relative strength of the magnetic field in each region) can be optimized based on the particular magnetic orientation pattern for the secondary annular alignment component (e.g., whether the secondary annular alignment components have the purely radial magnetic orientation of  FIG.  12 C  or the pseudo-radial magnetic orientation of  FIG.  12 D ). Another consideration can be the coefficient of friction between the surfaces of the devices containing primary and secondary alignment components; lower friction decreases resistance to the shear force exerted by the annular magnetic alignment components. 
     A radially-symmetric closed-loop magnetic alignment system (e.g., magnetic alignment system  1200  of  FIGS.  12 A and  12 B ) 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 can be 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.  14    shows a simplified top-down view of a secondary alignment component  1418  according to some embodiments. Secondary alignment component  1418  includes sectors  1428   a - h  having radial magnetic orientations as shown by magnetic polarity indicators  1417   a - h . Each of sectors  1428   a - h  can include one or more secondary arcuate magnets. In this example, secondary magnets in sectors  1428   b ,  1428   d ,  1428   f , and  1428   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  1428   a ,  1428   c ,  1428   e , and  1428   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 adjacent sectors  1428   a - h  of secondary alignment component  1418  have alternating magnetic orientations. 
     A complementary primary alignment component can have sectors with correspondingly alternating magnetic orientations. For example,  FIG.  15 A  shows a perspective view of a magnetic alignment system  1500  according to some embodiments. Magnetic alignment system  1500  includes a secondary alignment component  1518  having alternating radial magnetic orientations (e.g., as shown in  FIG.  14   ) and a complementary primary alignment component  1516 . Some of the arcuate sections of magnetic alignment system  1500  are not shown in order to reveal internal structure; however, it should be understood that magnetic alignment system  1500  can be a complete annular structure. Also shown are components  1502 , which can include, for example, inductive coil assemblies or other components located within the central region of primary annular alignment component  1516  and/or secondary annular alignment component  1518 . Magnetic alignment system  1500  can be a closed-loop magnetic alignment system similar to magnetic alignment system  1000  described above and can include arcuate sectors  1501   b ,  1501   c  of alternating magnetic orientations, with each arcuate sector  1501   b ,  1501   c  including one or more arcuate magnets in each of primary annular alignment component  1516  and secondary annular alignment component  1518 . In some embodiments, the closed-loop configuration of magnetic alignment system  1500  can reduce or prevent magnetic field leakage that may affect component  1502 . Like magnetic alignment system  1200 , magnetic alignment system  1500  can include a gap  1503  between two sectors. 
       FIG.  15 B  shows an axial cross-section view through one of arcuate sectors  1501   b , and  FIG.  15 C  shows an axial cross-section view through one of arcuate sectors  1501   c . Arcuate sector  1501   b  includes a primary magnet  1526   b  and a secondary magnet  1528   b . As shown by orientation indicator  1517   b , secondary magnet  1528   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  1500 . Like primary magnets  1026  described above, primary magnet  1526   b  includes an inner arcuate magnetic region  1552   b , an outer arcuate magnetic region  1554   b , and a central non-magnetized region  1556   b  (which can include, e.g., an air gap or a region of nonmagnetic or non-magnetized material). Inner arcuate magnetic region  1552   b  has a magnetic polarity oriented axially such that the north magnetic pole is toward secondary magnet  1528   b , as shown by indicator  1553   b , while outer arcuate magnetic region  1554   b  has an opposite magnetic orientation, with the south magnetic pole oriented toward secondary magnet  1528   b , as shown by indicator  1555   b . As described above with reference to  FIG.  10 B , the arrangement of magnetic orientations shown in  FIG.  15 B  results in magnetic attraction between primary magnet  1526   b  and secondary magnet  1528   b.    
     As shown in  FIG.  15 C , arcuate sector  1501   c  has a “reversed” magnetic orientation relative to arcuate sector  1501   b . Arcuate sector  1501   c  includes a primary magnet  1526   c  and a secondary magnet  1528   c . As shown by orientation indicator  1517   c , secondary magnet  1528   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  1500 . Like primary magnets  1026  described above, primary magnet  1526   c  includes an inner arcuate magnetic region  1552   c , an outer arcuate magnetic region  1554   c , and a central non-magnetized region  1556   c  (which can include, e.g., an air gap or a region of nonmagnetic or non-magnetized material). Inner arcuate magnetic region  1552   c  has a magnetic polarity oriented axially such that the south magnetic pole is toward secondary magnet  1528   c , as shown by indicator  1553   c , while outer arcuate magnetic region  1554   c  has an opposite magnetic orientation, with the north magnetic pole oriented toward secondary magnet  1528   c , as shown by indicator  1555   c . As described above with reference to  FIG.  10 B , the arrangement of magnetic orientations shown in  FIG.  15 C  results in magnetic attraction between primary magnet  1526   c  and secondary magnet  1528   c.    
     An alternating arrangement of magnetic polarities as shown in  FIGS.  14  and  15 A- 8 C  can create a “ratcheting” feel when secondary alignment component  1518  is aligned with primary alignment component  1516  and one of alignment components  1516 ,  1518  is rotated relative to the other about the common axis. For instance, as secondary alignment component  1516  is rotated relative to primary alignment component  1516 , each radially-outward magnet  1528   b  alternately comes into proximity with a complementary magnet  1526   b  of primary alignment component  1516 , resulting in an attractive magnetic force, or with an anti-complementary magnet  1526   c  of primary alignment component  1516 , resulting in a repulsive magnetic force. If primary magnets  1526   b ,  1526   c  and secondary magnets  1528   b ,  1528   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  1526   b ,  1528   b  and  1526   c ,  1528   c  are in proximity. In other rotational orientations, a torque toward a stable rotational orientation can be experienced. 
     In the examples shown in  FIGS.  14  and  15 A- 8 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.  16 A  shows a simplified top-down view of a secondary alignment component  1618  according to some embodiments. Secondary alignment component  1618  includes secondary magnets  1628   b  with radially outward magnetic orientations and secondary magnets  1628   c  with radially inward orientations, similarly to secondary alignment component  1518  described above. In this example, the magnets are arranged such that a pair of outwardly-oriented magnets  1628   b  (forming a first sector  1601 ) are adjacent to a pair of inwardly-oriented magnets  1628   c  (forming a second sector  1603  adjacent to first sector  1601 ). The pattern of alternating sectors (with two magnets per sector) repeats around the circumference of secondary alignment component  1618 . Similarly,  FIG.  16 B  shows a simplified top-down view of another secondary alignment component  1618 ′ according to some embodiments. Secondary alignment component  1618 ′ includes secondary magnets  1628   b  with radially outward magnetic orientations and secondary magnets  1628   c  with radially inward orientations. In this example, the magnets are arranged such that a group of four radially-outward magnets  1628   b  (forming a first sector  1611 ) is adjacent to a group of four radially-inward magnets  1628   c  (forming a second sector  1613  adjacent to first sector  1611 ). The pattern of alternating sectors (with four magnets per sector) repeats around the circumference of secondary alignment component  1618 ′. Although not shown in  FIGS.  16 A and  16 B , the structure of a complementary primary alignment component for secondary alignment component  1618  or  1618 ′ should be apparent in view of  FIGS.  15 A- 8 C . A shear force profile for the alignment components of  FIGS.  16 A  and  16 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 magnetic orientations of different sectors within the primary and/or secondary alignment components. As just one example,  FIG.  17    shows a simplified top-down view of a secondary alignment component  1718  according to some embodiments. Secondary alignment component has sectors  1728   a - h  with sector-dependent magnetic orientations as shown by magnetic polarity indicators  1717   a - h . In this example, secondary alignment component  1718  can be regarded as bisected by bisector line  1701 , which defines two halves of secondary alignment component  1718 . In a first half  1703 , sectors  1728   e - h  have magnetic polarities oriented radially outward, similarly to examples described above. 
     In the second half  1705 , sectors  1728   a - d  have magnetic polarities oriented substantially parallel to bisector line  1701  rather than radially. In particular, sectors  1728   a  and  1728   b  have magnetic polarities oriented in a first direction parallel to bisector line  1701 , while sectors  1728   c  and  1728   d  have magnetic polarities oriented in the direction opposite to the direction of the magnetic polarities of sectors  1728   a  and  1728   b . A complementary primary alignment component can have an inner annular region with magnetic north pole oriented toward secondary alignment component  1718 , an outer annular region with magnetic north pole oriented away from secondary alignment component  1718 , 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  1718  can modify the shear force profile such that secondary alignment component  1718  generates less shear force resisting motion in the direction toward second half  1705  (upward in the drawing) than in the direction toward first half  1703  (downward in the drawing). 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  1718  is oriented in the portable electronic device such that half-annulus  1705  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. 
     In the embodiments described above, the secondary annular magnetic alignment component has a magnetic orientation that is generally aligned in the transverse plane. In some alternative embodiments, a secondary annular magnetic alignment component can instead have a quad-pole configuration similar to that of primary annular magnetic alignment component  1016  of  FIGS.  10 A and  10 B , with or without a DC shield (which, if present, can be similar to DC shield  1014  of  FIGS.  10 A and  10 B ) on the distal surface of the secondary arcuate magnets. Using quad-pole magnetic configurations in both the primary and secondary alignment components can provide a closed-loop DC magnetic flux path and a strong sensation of “snappiness”; however, the thickness of the secondary magnetic alignment component may need to be increased to accommodate the quad-pole magnets and DC shield, which may increase the overall thickness of a portable electronic device that houses the secondary magnetic alignment component. To reduce thickness, the DC shield on the distal surface of the secondary alignment component can be omitted; however, omitting the DC shield may result in increased flux leakage into neighboring components. 
     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 that exert 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 (e.g., high snappiness), avoidance of DC flux leakage into other components, and other design considerations. 
     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  1200  of  FIGS.  12 A- 5 B  may not define a preferred rotational orientation. Radially alternating magnetic alignment system  1500  of  FIGS.  15 A- 8 C  can define multiple equally preferred rotational orientations. For some applications, such as alignment of a portable electronic device with a wireless charger puck or mat, rotational orientation may not be a concern. In other applications, such as alignment of a portable electronic device in a docking station or other mounting accessory, a particular rotational alignment may be desirable. Accordingly, in some embodiments an annular magnetic alignment component can be augmented with one or more rotational alignment components positioned outboard of and spaced apart from the annular magnetic alignment components. The rotational alignment component(s) can help guide devices into a target rotational orientation relative to each other. 
       FIG.  18    shows an example of a magnetic alignment system with an annular alignment component and a rotational alignment component according to some embodiments.  FIG.  18    shows respective proximal surfaces of a portable electronic device  1804  and an accessory device  1802 . In this example, primary alignment components of the magnetic alignment system are included in an accessory device  1802 , and secondary alignment components of the magnetic alignment system are included in a portable electronic device  1804 . Portable electronic device  1804  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  1802  can be, for example, a charging dock that supports portable electronic device  1804  such that its display is visible and accessible to a user. For instance, accessory device  1802  can support portable electronic device  1804  such that the display is vertical or at a conveniently tilted angle for viewing and/or touching. In the example shown, accessory device  1802  supports portable electronic device  1804  in a “portrait” orientation (shorter sides of the display at the top and bottom); however, in some embodiments accessory device  1802  can support portable electronic device  1804  in a “landscape” orientation (longer sides of the display at the top and bottom). Accessory device  1802  can also be mounted on a swivel, gimbal, or the like, allowing the user to adjust the orientation of portable electronic device  1804  by adjusting the orientation of accessory device  1802 . 
     As described above, components of a magnetic alignment system can include a primary annular alignment component  1816  disposed in accessory device  1802  and a secondary annular alignment component  1818  disposed in portable electronic device  1804 . Primary annular alignment component  1816  can be similar or identical to any of the primary alignment components described above. For example, primary annular alignment component  1816  can be formed of arcuate magnets  1826  arranged in an annular configuration. Although not shown in  FIG.  18   , one or more gaps can be provided in primary annular alignment component  1816 , e.g., by omitting one or more of arcuate magnets  1826  or by providing a gap at one or more interfaces  1830  between adjacent arcuate magnets  1826 . In some embodiments, each arcuate magnet  1826  can include an inner arcuate region having a first magnetic orientation (e.g., axially oriented in a first direction), an outer arcuate region having a second magnetic orientation opposite the first magnetic orientation (e.g., axially oriented opposite the first direction), and a central non-magnetized arcuate region between the inner and outer regions (as described above, the non-magnetized central region can include an air gap or a nonmagnetic material). In some embodiments, primary annular alignment component  1816  can also include a DC shield (not shown) on the distal side of arcuate magnets  1826 . 
     Likewise, secondary annular alignment component  1818  can be similar or identical to any of the secondary alignment components described above. For example, secondary annular alignment component  1818  can be formed of arcuate magnets  1828  arranged in an annular configuration. Although not shown in  FIG.  18   , one or more gaps can be provided in secondary annular alignment component  1818 , e.g., by omitting one or more arcuate magnets  1828  or by providing a gap at one or more interfaces  1832  between adjacent magnets  1828 . As described above, arcuate magnets  1828  can provide radially-oriented magnetic polarities. For instance, all sectors of secondary annular alignment component  1818  can have a radially-outward magnetic orientation or a radially-inward magnetic orientation, or some sectors of secondary annular alignment component  1818  may have a radially-outward magnetic orientation while other sectors of secondary annular alignment component  1818  have a radially-inward magnetic orientation. 
     As described above, primary annular alignment component  1816  and secondary annular alignment component  1818  can provide shear forces that promote alignment in the lateral plane so that center point  1801  of primary annular alignment component  1816  aligns with center point  1803  of secondary annular alignment component  1818 . However, primary annular alignment component  1816  and secondary annular alignment component  1818  might not provide torque 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.  18   , a primary rotational alignment component  1822  can be disposed outboard of and spaced apart from primary annular alignment component  1816  while a secondary rotational alignment component  1824  is disposed outboard of and spaced apart from secondary annular alignment component  1818 . Secondary rotational alignment component  1824  can be positioned at a fixed distance (y 0 ) from center point  1803  of secondary annular alignment component  1818  and centered between the side edges of portable electronic device  1804  (as indicated by distance xo from either side edge). Similarly, primary rotational alignment component  1822  can be positioned at the same distance y 0  from center point  1801  of primary annular alignment component  1816  and located at a rotational angle that results in a torque profile that favors the desired orientation of portable electronic device  1804  relative to accessory device  1802  when secondary rotational alignment component  1824  is aligned with primary rotational alignment component  1822 . 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  1822  and secondary rotational alignment component  1824  can be implemented using one or more magnets (e.g., rare earth magnets such as NdFeB) each of which has each been magnetized such that its magnetic polarity is oriented in a desired direction. In the example of  FIG.  18   , the magnets have rectangular shapes; however, other shapes (e.g., rounded shapes) can be substituted. The magnetic orientations of rotational alignment components  1822  and  1824  can be complementary so that when the proximal surfaces of rotational alignment components  1822  and  1824  are near each other, an attractive magnetic force is exerted. This attractive magnetic force can help to rotate portable electronic device  1804  and accessory device  1802  into a preferred rotational orientation in which the proximal surfaces of rotational alignment components  1822  and  1824  are aligned with each other. Examples of magnetic orientations for rotational alignment components  1822  and  1824  that can be used to provide a desired attractive force are described below. In some embodiments, primary rotational alignment component  1822  and secondary rotational alignment component  1824  can have the same lateral (xy) dimensions and the same thickness. The dimensions can be chosen based on a desired magnetic field strength and/or torque, 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 (x direction) by about 18 mm (y direction), and the thickness can be anywhere from about 0.3 mm to about 1.5 mm; the particular dimensions can be chosen based on the sizes of the devices that are to be aligned. In some embodiments, each of primary rotational alignment component  1822  and secondary rotational alignment component  1824  can be implemented using two or more 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.  19 A and  19 B  show an example of rotational alignment according to some embodiments. In  FIG.  19 A , accessory device  1802  is placed on the back surface of portable electronic device  1804  such that primary annular alignment component  1816  and secondary alignment component  1818  are aligned with each other in the lateral plane such that, in the view shown, center point  1801  of primary annular alignment component  1816  overlies center point  1803  of secondary annular alignment component  1818 . A relative rotation is present such that rotational alignment components  1822  and  1824  are not aligned. In this configuration, an attractive force between rotational alignment components  1822  and  1824  can urge portable electronic device  1804  and accessory device  1802  toward a target rotational orientation. In  FIG.  19 B , the attractive magnetic force between rotational alignment components  1822  and  1824  has brought portable electronic device  1804  and accessory device  1802  into the target rotational alignment with the sides of portable electronic device  1804  parallel to the sides of accessory device  1802 . In some embodiments, the attractive magnetic force between rotational alignment components  1822  and  1824  can also help to hold portable electronic device  1804  and accessory device  1802  in a fixed rotational alignment. 
     Rotational alignment components  1822  and  1824  can have various patterns of magnetic orientations. As long as the magnetic orientations of rotational alignment components  1822  and  1824  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.  20 A- 21 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 the magnetic orientation of shown. 
       FIGS.  20 A and  20 B  show a perspective view and a top view of a rotational alignment component  2024  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.  20 A , rotational alignment component  2024  can have a uniform magnetic orientation along the axial direction. Accordingly, as shown in  FIG.  20 B , a north magnetic pole (N) can be nearest the proximal surface  2003  of rotational alignment component  2024 . A complementary z-pole alignment component would have 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. 
       FIGS.  21 A and  21 B  show a perspective view and a top view of a rotational alignment component  2124  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.  21 A , rotational alignment component  2124  has a first magnetized region  2125  with a magnetic orientation along the axial direction such that the north magnetic pole (N) is nearest the proximal (+z) surface  2103  of rotational alignment component  2124 , a second magnetized region  2127  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  2103 . Between magnetized regions  2125  and  2127  is a neutral region  2129  that is not strongly magnetized. In some embodiments, rotational alignment component  2124  can be formed from a single piece of magnetic material that is exposed to a magnetizer to create regions  2125 ,  2127 ,  2129 . Alternatively, rotational alignment component  2124  can be formed using two pieces of magnetic material with a nonmagnetic material or an air gap between them. As shown in  FIG.  21 B , the proximal surface of rotational alignment component  2124  can have one region having a “north” polarity and another region having a “south” polarity. A complementary quad-pole rotational alignment component would have corresponding regions of south and north polarity at the proximal surface. 
       FIGS.  21 C and  21 D  show a perspective view and a top view of a rotational alignment component  2154  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.  21 A , rotational alignment component  2154  has an outer magnetized region  2155  with a magnetic orientation along the axial direction such that the north magnetic pole (N) is nearest the proximal (+z) surface  2103  of rotational alignment component  2154 , and an inner magnetized region  2157  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  2104 . Between magnetized regions  2155  and  2157  is a neutral annular region  2159  that is not strongly magnetized. In some embodiments, rotational alignment component  2154  can be formed from a single piece of magnetic material that is exposed to a magnetizer to create regions  2155 ,  2157 ,  2159 . Alternatively, rotational alignment component  2154  can be formed using two pieces of magnetic material with a nonmagnetic material or an air gap between them. As shown in  FIG.  21 B , the proximal surface of rotational alignment component  2154  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 would have an annular outer region of south polarity and an inner region of north polarity. 
       FIGS.  21 E and  21 F  show a perspective view and a top view of a rotational alignment component  2174  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.  21 A , rotational alignment component  2174  has a central magnetized region  2175  with a magnetic orientation along the axial direction such that the south magnetic pole (S) is nearest the proximal (+z) surface  2105  of rotational alignment component  2174 , and outer magnetized regions  2177 ,  2179  with a magnetic orientation opposite to the magnetic orientation of central region  2175  such that the north magnetic pole (N) is nearest to proximal surface  2105 . Between central magnetized region  2175  and each of outer magnetized regions  2177 ,  2179  is a neutral annular region  2171 ,  2173  that is not strongly magnetized. In some embodiments, rotational alignment component  2174  can be formed from a single piece of magnetic material that is exposed to a magnetizer to create regions  2175 ,  2177 ,  2179 . Alternatively, rotational alignment component  2174  can be formed using three pieces of magnetic material with nonmagnetic materials or air gaps between them. As shown in  FIG.  21 B , the proximal surface can 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 would 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.  20 A- 21 F  are illustrative and that other configurations can 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. For example, it can be desirable to provide a strong tactile “clocking” feel to a user when close to the desired rotational alignment. The “clocking” feel 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.  18   ), as well as the strength of the magnetic fields of the rotational alignment components (which can depend on the size of the rotational alignment component) and whether the annular alignment components exert any torque toward a preferred rotational orientation. 
       FIG.  22    shows graphs of torque as a function of angular rotation (in degrees) for an alignment system of the kind shown in  FIG.  18   , 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  1822  and  1824  are in closest proximity). 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  1816  and  1818  are rotationally symmetric and do not exert torque about the z axis defined by center points  1801  and  1803 . Three different magnetization configurations are considered. Line  2204  corresponds to the quad-pole configuration of  FIGS.  21 A and  21 B . Line  2205  corresponds to the annulus design configuration of  FIGS.  21 A and  21 B . Line  2206  corresponds to the triple-pole configuration of  FIGS.  21 A and  21 B . As shown, the annulus design (line  2205 ) and triple-pole (line  2206 ) 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  2204 ). 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.  22    are illustrative, and that torque in a particular embodiment can depend on a variety of other factors in addition to the magnetization configuration, such as the magnet volume, aspect ratio, and distance y 0  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.  23    shows a portable electronic device, in this example adapter  120 , having an alignment system  2300  inside enclosure  410  with multiple rotational alignment components according to some embodiments. In this example, alignment system  2300  includes an annular alignment component  2318  and a set of rotational alignment components  2324  positioned at various locations around the perimeter of annular alignment component  2318 . In this example, there are four rotational alignment components  2324  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  2324  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  2324  can have different magnetization configurations from each other. It should be noted that rotational alignment components  2324  can be placed close to the perimeter of annular alignment component  2318 , and the larger number of magnetic components can provide increased torque at a smaller radius. In this example, an additional rotational alignment component  2330  can be used along with, or instead of rotational alignment components  2324 . Additional rotational alignment component  2330  can be arranged to be attracted to a corresponding rotational alignment component in a phone or other electronic device  180  (shown in  FIG.  1   .) This can be particularly helpful when aligning electronic device  180  to adapter  120  in either a portrait or landscape orientation. 
     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  1804  of  FIG.  18    can align rotationally to accessory device  1802  (which has both annular alignment component  1816  and rotational alignment component  1822 ) as well as aligning laterally to another accessory (not shown) that has annular alignment component  1816  but not rotational alignment component  1822 . In the latter case, lateral alignment can be achieved, e.g., to support efficient wireless charging, but there might be no preferred rotational alignment, or rotational alignment can 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 magnetic alignment component can be used together with any type of annular magnetic alignment component (e.g., primary annular magnetic alignment components, secondary annular magnetic alignment components, or auxiliary annular magnetic alignment components as described below). 
     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.  24 A through  24 C  illustrate examples of moving magnets according to an embodiment of the present invention. In this example, first electronic device  2400  can be any of the adapters shown above, a wireless charging device, or other device having a magnet  2410  (which can be, e.g., any of the annular or other magnetic alignment components described herein.) In  FIG.  24 A , moving magnet  2410  can be housed in a first electronic device  2400 . First electronic device  2400  can include device enclosure  2430 , magnet  2410 , and shield  2420 . Magnet  2410  can be in a first position (not shown) adjacent to nonmoving shield  2420 . In this position, magnet  2410  can be separated from device enclosure  2430 . As a result, the magnetic flux  2412  at a surface of device enclosure  2430  can be relatively low, thereby protecting magnetic devices and magnetically stored information, such as information stored on payment cards. As magnet  2410  in first electronic device  2400  is attracted to a second magnet (not shown) in a second electronic device (not shown), magnet  2410  can move, for example it can move away from shield  2420  to be adjacent to device enclosure  2430 , as shown. With magnet  2410  at this location, magnetic flux  2412  at surface of device enclosure  2430  can be relatively high. This increase in magnetic flux  2412  can help to attract the second electronic device to first electronic device  2400 . 
     With this configuration, it can take a large amount of magnetic attraction for magnet  2410  to separate from shield  2420 . 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.  24 B , line  2460  can be used to indicate a split of shield  2420  into a shield  2440  and return plate  2450 . Shield  2420 , and the other shields shown here or otherwise utilized by embodiments of the present invention, can be formed of a material that has high magnetic permeability, such as stainless steel. Return plate  2450 , and the other return plates shown here or otherwise utilized by embodiments of the present invention, can be formed of a material that has high magnetic permeability, such as stainless steel. 
     In  FIG.  24 C , moving magnet  2410  can be housed in first electronic device  2400 . First electronic device  2400  can include device enclosure  2430 , magnet  2410 , shield  2440 , and return plate  2450 . In the absence of a magnetic attraction, magnet  2410  can be in a first position (not shown) such that shield  2440  can be adjacent to return plate  2450 . Again, in this configuration, magnetic flux  2412  at a surface of device enclosure  2430  can be relatively low. As magnet  2410  and first electronic device is attracted to a second magnet (not shown) in a second electronic device (not shown), magnet  2410  can move, for example it can move away from return plate  2450  to be adjacent to device enclosure  2430 , as shown. In this configuration, shield  2440  can separate from return plate  2450  and the magnetic flux  2412  at a surface of device enclosure  2430  can be increased. As before, this increase in magnetic flux  2412  can help to attract the second electronic device to the first electronic device  2400 . 
     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.  25 A and  25 B  illustrate a moving magnetic structure according to an embodiment of the present invention In this example, first electronic device  2500  can be any of the adapters shown above, a wireless charging device, or other device having a magnet  2510  (which can be, e.g., any of the annular or other magnetic alignment components described herein.)  FIG.  25 A  illustrates a moving first magnet  2510  in a first electronic device  2500 . First electronic device  2500  can include first magnet  2510 , protective surface  2512 , housings  2520  and  2522 , compliant structure  2524 , shield  2540 , and return plate  2550 . In this figure, first magnet  2510  is not attracted to a second magnet (not shown), and therefore shield  2540  is magnetically attracted to or attached to return plate  2550 . In this position, compliant structure  2524  can be expanded or relaxed. Compliant structure  2524  can be formed of an elastomer, silicon rubber open cell foam, silicon rubber, polyurethane foam, or other foam or other compressible material. 
     In  FIG.  25 B , second electronic device  2560  has been brought into proximity of first electronic device  2500 . Second magnet  2570  can attract first magnet  2510 , thereby causing shield  2540  and return plate  2550  to separate from each other. Housings  2520  and  2522  can compress compliant structure  2524 , thereby allowing protective surface  2512  of first electronic device  2500  to move towards or adjacent to housing  2580  of second electronic device  2560 . Second magnet  2570  can be held in place in second electronic device  2560  by housing  2590  or other structure. As second electronic device  2560  is removed from first electronic device  2500 , first magnet  2510  and shield  2540  can be magnetically attracted to return plate  2550 , as shown in  FIG.  25 A . 
       FIGS.  26 A and  26 B  illustrate moving magnetic structures according to an embodiment of the present invention. In this example, first electronic device  2600  can be any of the adapters shown above, a wireless charging device, or other device having a magnet  2610  (which can be, e.g., any of the annular or other magnetic alignment components described herein.)  FIG.  26 A  illustrates a moving first magnet  2610  in a first electronic device  2600 . First electronic device  2600  can include first magnet  2610 , pliable surface  2612 , housing portions  2620  and  2622 , shield  2640 , and return plate  2650 . In this figure, first magnet  2610  is not attracted to a second magnet, and therefore shield  2640  is magnetically attached or attracted to return plate  2650 . In this position, pliable surface  2612  can be relaxed. Pliable surface  2612  can be formed of an elastomer, silicon rubber open cell foam, silicon rubber, polyurethane foam, or other foam or other compressible material. 
     In  FIG.  26 B , second electronic device  2660  has been brought into the proximity of first electronic device  2600 . Second magnet  2670  can attract first magnet  2610 , thereby causing shield  2640  and return plate  2650  to separate from each other. First magnet  2610  can stretch pliable surface  2612  towards second electronic device  2660 , thereby allowing first magnet  2610  of first electronic device  2600  to move towards housing  2680  of second electronic device  2660 . Second magnet  2670  can be held in place in second electronic device  2660  by housing  2690  or other structure. As second electronic device  2660  is removed from first electronic device  2600 , first magnet  2610  and shield  2640  can be magnetically attracted to return plate  2650  as shown in  FIG.  26 A . 
       FIG.  27    to  FIG.  29    illustrate a moving magnetic structure according to an embodiment of the present invention. In this example, first electronic device  2700  can be any of the adapters shown above, a wireless charging device, or other device having a magnet  2710  (which can be, e.g., any of the annular or other magnetic alignment components described herein.) In  FIG.  27   , first magnet  2710  and shield  2740  can be magnetically attracted or attached to return plate  2750  in first electronic device  2700 . First electronic device  2700  can be at least partially housed in device enclosure  2720 . In  FIG.  28   , housing  2780  of second electronic device  2760  can move laterally across a surface of device enclosure  2720  of first electronic device  2700  in a direction  2785 . Second magnet  2770  in second electronic device  2760  can begin to attract first magnet  2710  in first electronic device  2700 . This magnetic attraction  2715  can cause first magnet  2710  and shield  2740  to pull away from return plate  2750  by overcoming the magnetic attraction  2745  between shield  2740  and return plate  2750 . In  FIG.  29   , second magnet  2770  in second electronic device  2760  has become aligned with first magnet  2710  in first electronic device  2700 . First magnet  2710  and shield  2740  have pulled away from return plate  2750  thereby reducing the magnetic attraction  2745 . First magnet  2710  has moved nearby or adjacent to device enclosure  2720 , thereby increasing the magnetic attraction  2715  to second magnet  2770  in second electronic device  2760 . 
     As shown in  FIG.  27    through  FIG.  29   , the magnetic attraction between first magnet  2710  in first electronic device  2700  and the second magnet  2770  in the second electronic device  2760  can increase when first magnet  2710  and shield  2740  pull away from return plate  2750 . This is shown graphically in the following figures. 
       FIG.  30    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.  27 - 36   , with a large offset between first magnet  2710  and second magnet  2970 , first magnet  2710  and shield  2740  can remain attached to return plate  2750  in first electronic device  2700  and the magnetic attraction  2715  can be minimal. The shear force necessary to overcome this magnetic attraction is illustrated here as curve  3010 . As shown in  FIG.  28   , as the offset or lateral distance between first magnet  2710  and second magnet  2770  decreases, first magnet  2710  and shield  2740  can pull away or separate from return plate  2750 , thereby increasing the magnetic attraction  2715  between first magnet  2710  and second magnet  2770 . This is illustrated here as discontinuity  3020 . As shown in  FIG.  29   , as first magnet  2710  and second magnet  2770  come into alignment, the magnetic attraction  2715  increases along curve  3030  to a maximum  3040 . The difference between curve  3010  and curve  3030  can show the increase in magnetic attraction between a phone or other electronic device, such as second electronic device  2760  and an attachable wallet or wireless charging device, such as first electronic device  2700 , that results from first magnet  2710  being able to move axially. It should also be noted that in this example first magnet  2710  does not move in a lateral direction, though in other examples it is capable of such movement. Where first magnet  2710  is capable of moving in a lateral direction, curve  3030  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  2710 . 
       FIG.  31    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  2710  and second magnet  2770 , there it is no shear force to move second magnet  2770  relative to first magnet  2710 , as shown in  FIG.  27   . As the offset is increased, the shear force, that is the force attempting to realign the magnets, can increase along curve  3140 . At discontinuity  3110 , first magnet  2710  and shield  2740  can return to return plate  2750  (as shown in  FIGS.  27 - 36   ), thereby decreasing the magnetic shear force to point  3120 . The magnetic shear force can continue to drop off along curve  3130  as the offset increases. The difference between curve  3130  and curve  3140  can show the increase in magnetic attraction between a phone or other electronic device, such as second electronic device  2760  and an attachable wallet or wireless charging device, such as first electronic device  2700 , that results from first magnet  2710  being able to move axially. It should also be noted that in this example first magnet  2710  does not move in a lateral direction, though in other examples it is capable of such movement. Where first magnet  2710  is capable of moving in a lateral direction, curve  3130  can remain at zero until the lateral movement of the second magnet  2770  overcomes the range of possible lateral movement of first magnet  2710 . 
     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.  32 A and  32 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  3200  can be a wireless charger device or other device having a first magnet  3210  (which can be, e.g., any of the annular magnetic alignment components described above). In  FIG.  32 A , first magnet  3210  and shield  3240  can be magnetically attracted or attached to return plate  3250  in first electronic device  3200 . First electronic device  3200  can be housed in device enclosure  3220 . Some or all of a surface of device enclosure  3220  can have a coating, layer, or other structure  3222 . Structure  3222  can provide a high friction or high stiction surface. In  FIG.  32 B , first magnet  3210  and shield  3240  can be attracted to a second magnet (not shown) in a second electronic device (not shown.) As before, the separation of first magnet  3210  and shield  3240  from return plate  3250  can provide an increased amount of magnetic flux to hold the second electronic device in place relative to first electronic device  3200 . Structure  3222  can increase the friction or stiction between first electronic device  3200  and the second electronic device in a lateral or shear direction. 
       FIGS.  33 A and  33 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  3300  can be a wireless charger device or other device having a first magnet  3310  (which can be, e.g., any of the annular magnetic alignment components described above). In  FIG.  33 A , first magnet  3310  and shield  3340  can be magnetically attracted or attached to return plate  3350  in first electronic device  3300 . First electronic device  3300  can be housed in device enclosure  3320 . Some or all of a surface of device enclosure  3320  can have a coating, layer, or other structure  3322 , in this example over first magnet  3310 . Structure  3322  can provide a high friction or high stiction surface. In  FIG.  33 B , first magnet  3310  and shield  3340  can be attracted to a second magnet (not shown) in a second electronic device (not shown.) This can cause first magnet  3310  and shield  3340  to separate from return plate  3250 , thereby deforming structure  3322 , which can be pliable or compliant. As before, first magnet  3310  can provide an increased amount of magnetic flux to hold the second electronic device in place relative to first electronic device  3300 . Structure  3322  can increase the friction or stiction between first electronic device  3300  and the second electronic device in a lateral or shear direction. 
       FIGS.  34 A and  34 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  3400  can be a wireless charger device or other device having a first magnet  3410  (which can be, e.g., any of the primary annular magnetic alignment components described above). In  FIG.  34 A , 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 housed in device enclosure  3420 . Some or all of a surface of device enclosure  3420  can have a coating, layer, or other structure  3422 , in this example over a top surface of first electronic device  3400 . Structure  3422  can provide a high friction or high stiction surface. In  FIG.  34 B , first magnet  3410  and shield  3440  can be attracted to a second magnet (not shown) in a second electronic device (not shown.) The separation of first magnet  3410  and shield  3440  from return plate  3450  can push the top surface formed by structure  3422  upward where it can engage the second electronic device with a high-friction surface. As before, first magnet  3410  can provide an increased amount of magnetic flux to hold the second electronic device in place relative to first electronic device  3400 . Structure  3422  can increase the friction or stiction between first electronic device  3400  and the second electronic device in a lateral or shear direction. 
       FIGS.  35 A and  35 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  3500  can be a wireless charger device or other device having a first magnet  3510  (which can be, e.g., any of the annular magnetic alignment components described above). In  FIG.  35 A , first magnet  3510  and first shield  3550  can be fixed in place in device enclosure  3520  of first electronic device  3500 . Some or all of a surface of device enclosure  3520  can have a coating, layer, or other structure  3522 . Structure  3522  can provide a high friction or high stiction surface. First electronic device  3500  can further include a moving second magnet  3591  and second shield  3592 , which can be attached to sliding mechanism  3590 . In  FIG.  35 B , as a second electronic device (not shown) comes into contact with first electronic device  3500 , sliding mechanism  3590  can be depressed, thereby moving second magnet  3591  away from second shield  3592  and the top surface of device enclosure  3520 . The polarity of second magnet  3591  can be in opposition to, or the opposite of, the polarity of first magnet  3510 , such that the net magnetic flux at a top surface of device enclosure  3520  is increased as sliding mechanism  3590  is depressed. Structure  3522  can increase the friction or stiction between first electronic device  3500  and the second electronic device in a lateral or shear direction. 
       FIG.  37    is a partially transparent view of the moving magnet structure of  FIG.  36   . First electronic device  3600  can be housed in device enclosure  3620 . As before, first electronic device  3600  can include inductive charging, near field communication complements, or other electronic circuits for components  3678 . Return plates  3650  (shown in  FIG.  36   ) can be attached to beams  3670 . 
       FIG.  38    is another cutaway side view of the electronic device of  FIG.  36   . First electronic device  3600  can be housed in device enclosure  3620 . As before, first electronic device  3600  can include inductive charging, near field communication components, or other electronic circuits for components  3678 . Return plates  3650  can be attached to beams  3670 . First magnets  3610  and shield  3640  can be attracted or attached to return plate  3650 . A high friction or high stiction structure  3622  can cover some or all of a top surface of first electronic device  3600 . Beams  3670  can be attached to return plates  3650 , can be anchored at points  3674 , and can have a tip  3672  extending above top surface of device enclosure  3620 . 
       FIGS.  39  and  40    illustrate the electronic device of  FIG.  36    as it engages with a second electronic device. In  FIG.  39   , second electronic device  3680  can include second magnets  3690 . Second electronic device  3680  can engage with first electronic device  3600 . First electronic device  3600  can include first magnets  3610 , shields  3640 , and return plates  3650 . Return plates  3650  can be attached to beams  3670 . Beams  3670  can include tips  3672  which can extend above a top surface of device enclosure  3620 . Tips  3672  can prevent second electronic device  3680  from engaging with the high friction or high stiction structure  3622  of first electronic device  3600  until the second electronic device  3680  is aligned, or nearly aligned, with first electronic device  3600 . Beams  3670  can be attached at points  3674  to device enclosure  3620 . First electronic device  3600  can include components  3678 . 
     In  FIG.  40   , second electronic device  3680  can be aligned with the first electronic device  3600 . When this occurs, first magnets  3610  and shields  3640  can detach from return plates  3650 . This can increase magnetic flux between second magnets  3690  in second electronic device  3680  and first magnets  3610  and first electronic device  3600 . Tips  3672  can become depressed into device enclosure  3620  due to this increase magnetic attraction, thereby further pushing return plates  3650  away from shields  3640 . High friction or high stiction structure  3622  can engage with second electronic device  3680  to increase the shear force necessary for a detachment of second electronic device  3680  from first electronic device  3600 . 
     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.  41 A and  41 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  4100  can be a wireless charger device or other device having a first magnet  4110  (which can be, e.g., any of the annular magnetic alignment components described above). In  FIG.  41 A , magnet  4110 , shield  4140 , and structure  4170  can be housed by device enclosure  4120  in electronic device  4100 . Structure  4170  can include notch  4172 , which can fit in tab  4124 . In  FIG.  41 B , magnet  4110  has moved, taking along with it shield  4140  and structure  4170 . Notch  4172  accepts tab  4124  as shield  4140  detaches from return plate  4150 . This can constrain the motion of magnets  4110  in electronic device  4100 . Electronic device  4100  can include a top device enclosure portion  4122 . Tab  4124  can be formed as part of or separate from top device enclosure portion  4122 . 
       FIGS.  42 A and  42 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  4200  can be a wireless charger device or other device having a first magnet  4210  (which can be, e.g., any of the annular magnetic alignment components described above). In  FIG.  42 A , magnet  4210 , shield  4240 , and return plate  4250  can be housed in device enclosure  4220  of electronic device  4200 . Top device enclosure portion  4222  can include guide  4224 . Guide  4224  can constrain motion of magnet  4210  in electronic device  4200 . In FIG.  42 B, magnet  4210  and shield  4240  have detached from return plate  4250  and have been guided into position by guide  4224 . Guide  4224  can include one or more chamfered edges  4225 . Again, guide  4224  can be formed along with or separate from top device enclosure portion  4222  of electronic device  4200 . 
       FIGS.  43 A and  43 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  4300  can be a wireless charger device or other device having a first magnet  2410  (which can be, e.g., any of the annular magnetic alignment components described above). In  FIG.  43 A , magnet  4310 , shield  4340 , and return plate  4350  can be housed in device enclosure  4320  of electronic device  4300 . Magnet  4310  and shield  4340  can be supported by structure  4370 . Structure  4370  can be attached to anchor  4374  through actuators  4372 . Actuators  4372  can have hinges  4373  and  4375  at each end to allow structure  4370  to move relative to anchor  4374 . Anchor  4374  can be attached to, or formed as either part of, top device enclosure portion  4322  or device enclosure  4320 . In  FIG.  43 B , magnet  4310  and shield  4340  have detached from return plate  4350 . Actuators  4372  have changed positions but continued to connect structure  4370  to anchor  4374 . Anchor  4374  can be attached to, or formed as either part of, top device enclosure portion  4322  or device enclosure  4320 . 
     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, including device identification, from a tag circuit located in one device to a reader circuit located in another device. (As used herein, “NFC” encompasses various protocols, including known standard protocols, that use near-field electromagnetic radiation to communicate data between antenna structures, e.g., coils of wire, that are in proximity to each other.) For example, each device that has an annular magnetic alignment component can also have an NFC coil that can be disposed inboard of 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 an annular gap between the inductive charging coil and the annular magnetic alignment component. In some embodiments, an NFC protocol can be used to allow a portable electronic device to identify an accessory device when the respective magnetic alignment components of the portable electronic device and the accessory device are brought into alignment. For example, the NFC coil of a portable electronic device can be coupled to an NFC reader circuit while the NFC coil of an accessory device is coupled to an NFC tag circuit. When devices are brought into proximity, the NFC reader circuit of the portable electronic device can be activated to read the NFC tag of the accessory device. In this manner, the portable electronic device can obtain information (e.g., device identification) from the accessory device. 
     In some embodiments, an NFC reader in a portable electronic device can be triggered by detecting a change in a DC (or static) magnetic field within the portable electronic device that corresponds to a change expected when an accessory device having 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. 
     Examples of devices incorporating NFC circuitry and magnetic alignment components will now be described. 
     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.  44    shows an exploded view of a wireless charger device  4402  incorporating an NFC tag according to some embodiments, and  FIG.  45    shows a partial cross-section view of wireless charger device  4402  according to some embodiments. As shown in  FIG.  44   , wireless charger device  4402  can include an enclosure  4404 , which can be made of plastic or metal (e.g., aluminum), and a charging surface  4406 , which can be made of silicone, plastic, glass, or other material that is permeable to AC and DC magnetic fields. Charging surface  4406  can be shaped to fit within a circular opening  4403  at the top of enclosure  4404 . 
     A wireless transmitter coil assembly  4411  can be disposed within enclosure  4404 . Wireless transmitter coil assembly  4411  can include a wireless transmitter coil  4412  for inductive power transfer to another device as well as AC magnetic and/or electric shield(s)  4413  disposed around some or all surfaces of wireless transmitter coil  4412 . Control circuitry  4414  (which can include, e.g., a logic board and/or power circuitry) to control wireless transmitter coil  4412  can be disposed in the center of coil  4412  and/or underneath coil  4412 . In some embodiments, control circuitry  4414  can operate wireless transmitter coil  4412  in accordance with a wireless charging protocol such as the Qi protocol or other protocols. 
     A primary annular magnetic alignment component  4416  can surround wireless transmitter coil assembly  4411 . Primary annular magnetic alignment component  4416  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. (Examples are described above.) In some embodiments, the diameter and thickness of primary annular magnetic alignment component  4416  is chosen such that arcuate magnet sections of primary annular magnetic alignment component  4416  fit under a lip  4409  at the top surface of enclosure  4404 , as best seen in  FIG.  45   . For instance, each arcuate magnet section can be inserted into position under lip  4409 , either before or after magnetizing the inner and outer regions. In some embodiments, primary annular magnetic alignment component  4416  can have a gap  4436  between two adjacent arcuate magnet sections. Gap  4436  can be aligned with an opening  4407  in a side surface of enclosure  4404  to allow external wires to be connected to wireless transmitter coil  4412  and/or control circuitry  4414 . 
     A support ring subassembly  4440  can include an annular frame  4442  that extends in the axial direction and a friction pad  4444  at the top edge of frame  4442 . Friction pad  4444  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  4406 . Frame  4442  can be made of a material such as polycarbonate (PC), glass-fiber reinforced polycarbonate (GFPC), or glass-fiber reinforced polyamide (GFPA). Frame  4442  can have an NFC coil  4464  disposed thereon. For example, NFC coil  4464  can be a four-turn or five-turn solenoidal coil made of copper wire or other conductive wire that is wound onto frame  4442 . NFC coil  4464  can be electrically connected to NFC tag circuitry (not shown) that can be part of control circuitry  4414 . The relevant design principles of NFC circuits are well understood in the art and a detailed description is omitted. Frame  4442  can be inserted into a gap region  4417  between primary annular magnetic alignment component  4416  and wireless transmitter coil assembly  4411 . In some embodiments, gap region  4417  is shielded by AC shield  4413  from AC electromagnetic fields generated in wireless transmitter coil  4412  and is also shielded from DC magnetic fields of primary annular magnetic alignment component  4416  by the closed-loop configuration of the arcuate magnet sections. 
       FIG.  46    shows a flow diagram of a process  4600  that can be implemented in portable electronic device  5004  according to some embodiments. In some embodiments, process  4600  can be performed iteratively while portable electronic device  5004  is powered on. At block  4602 , process  4600  can determine a baseline magnetic field, e.g., using magnetometer  5080 . At block  4604 , process  4600  can continue to monitor signals from magnetometer  5080  until a change in magnetic field is detected. At block  4606 , process  4600  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  4602 . If, at block  4606 , the change in magnetic field matches a magnitude and direction of change associated with alignment of a complementary alignment component, then at block  4608 , process  4600  can activate the NFC reader circuitry associated with NFC coil  5060  to read an NFC tag of an aligned device. In some embodiments, NFC tags associated with different types of devices (e.g., a passive accessory versus an active accessory such as a wireless charger) are tuned to respond to different stimulating signals from the NFC reader circuitry, and information about the particular change in magnetic field can be used to determine a particular stimulating signal to be generated by the NFC reader circuitry. At block  4610 , process  4600  can receive identification information read from the NFC tag. At block  4612 , process  4600  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  4612 , process  4600  can optionally return to block  4602  to provide continuous monitoring of magnetometer  5080 . It should be understood that process  4600  is illustrative and that other processes may be performed in addition to or instead of process  4600 . 
     It will be appreciated that the NFC tag and NFC reader circuits described above are illustrative and that variations and modifications are possible. For example, coil designs can be modified by replacing wound wire coils with etched coils (or vice versa) and solenoidal coils with flat coils (or vice versa). “Wound wire” coils can be made using a variety of techniques, including by winding a wire, by stamping a coil from a copper sheet and molding plastic over the stamped part, or by using a needle dispenser to deposit wire on a plastic part; the wire can be heated so that it embeds into the softened plastic. Etched coils can be made by coating a surface with metal and etching away the unwanted metal. The number of turns in various NFC coils can be modified for a particular application. The choice of wound wire coils or etched coils for a particular device may depend on various design considerations. For instance, in devices that have an internal logic board, a wound wire NFC coil can terminate to the logic board; where a logic board is absent, an etched coil may simplify termination of the coil. Other design considerations may include the Q factor of the coil (a wound coil can provide higher Q in a smaller space) and/or ease of assembly. 
     Further, where a device that has an NFC tag circuit also has active circuitry (such as wireless charger devices that have active circuitry to control charging behavior), the NFC tag circuit is not limited to being a passive tag; an active NFC tag circuit can be provided to enable two-way communication with a compatible portable electronic device. For example, active NFC circuits in a portable electronic device and a wireless charger device can be used to support delivery of firmware updates to the wireless charger device. 
     Proximity-detection techniques can also be varied. For example, a different type of magnetometer (e.g., a single-axis magnetometer) can be used, or multiple magnetometers in different locations relative to the magnetic alignment components can be used. In some embodiments, a Hall effect sensor can be used instead of a magnetometer, although false positives may increase because a Hall effect sensor can generally only indicate a change or no-change rather than measuring a magnitude or direction of change. 
     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: 20210511
Publication Date: 20240109
Grant Date: 20240109
Priority Date: 20200805
Inventors: RASMUSSEN, Timothy J.
GRAHAM, Christopher S.
JOL, ERIC S.
Oro, Aaron A.
Daly, Miranda L
Kamei, Ibuki
Assignee: APPLE INC
CPC Classifications: [{"code": "F16M13/02", "inventive": true, "first": true, "tree": "[]"}, {"code": "G03B17/561", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0042", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/0075", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/24", "inventive": true, "first": true, "tree": "[]"}, {"code": "F16M13/02", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/0044", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B17/561", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16M11/041", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16M13/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16M11/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "F16M13/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "G03B17/561", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0042", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/24", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 80113695