PATENT DOCUMENT

Publication Number: US-9614378-B2
Application Number: US-201414500543-A
Country: US
Kind Code: B2

Title: Inductive charging interface with magnetic retention for electronic devices and accessories

Abstract:
An inductive charging interface with magnetic retention can be used for charging electronic devices and accessories. For example, a magnetic core of an inductive charging configuration may be divided into two magnetic elements, one element can be housed within a receptacle or receiving connector of housing of an electric device and the other element can be housed within a plug or transmission connector. The poles of the two elements of the magnetic core may create a magnetic field to retain the plug connector in an aligned, mated position with the receptacle connector of the electronic device in addition to directing magnetic flux to flow in a circular path around and between the two elements of the magnetic core, thereby inducing a current for charging the internal battery of a device.

Claims:
That which is claimed is: 
     
       1. A plug connector supporting inductive charging, the plug connector comprising:
 a permanent magnet generating a magnetic field that attracts a corresponding receptacle connector of an electronic device; 
 a wire wound around a magnetically permeable material to form an inductive transmission coil, the magnetically permeable material being in abutting contact with the permanent magnet such that the permanent magnet and the magnetically permeable material form a portion of a magnetic flux flow path when electrical current is applied to the wire. 
 
     
     
       2. The plug connector of  claim 1 , wherein the permanent magnet is a first permanent magnet and the plug connector further comprises a second permanent magnet, the first permanent magnet located at a first distal tip of the magnetically permeable material, the second permanent magnet located at a second distal tip of the magnetically permeable material, the magnetically permeable material extending between the first and second permanent magnets. 
     
     
       3. The plug connector of  claim 2 , wherein the magnetic flux flow path is a circular magnetic flux flow path when the plug connector is mated with the corresponding receptacle connector. 
     
     
       4. The plug connector of  claim 1 , wherein the permanent magnet is a first permanent magnet and the plug connector further comprises second and third permanent magnets, the first permanent magnet located at a first distal tip of the magnetically permeable material, the second permanent magnet located at a second distal tip of the magnetically permeable material and the third permanent magnet located at a third distal tip of the magnetically permeable material. 
     
     
       5. The plug connector of  claim 4 , wherein the plug connector forms first and second circular magnetic flux flow paths when mated with the corresponding receptacle connector. 
     
     
       6. The plug connector of  claim 1 , further comprising:
 an electrical connection coupled to the inductive transmission coil and configured to apply the current to the inductive transmission coil to induce a current in an inductive receiving coil of the corresponding receptacle connector. 
 
     
     
       7. The plug connector of  claim 1 , further comprising:
 a magnetically permeable window adjacent to the permanent magnet, the magnetically permeable window forming a portion of an exterior surface of the plug connector, the magnetically permeable window configured to allow magnetic flux to flow to and from the corresponding receptacle connector when the corresponding receptacle connector is mated with the plug connector. 
 
     
     
       8. An electronic device that supports inductive charging, the electronic device comprising:
 a receptacle connector having a mating surface configured to mate with a corresponding plug connector, the receptacle connector comprising:
 a permanent magnet generating a magnetic field that is configured to attract a corresponding plug connector and orients and aligns the corresponding plug connector with the receptacle connector; 
 a magnetically permeable material in abutting contact with the permanent magnet; and 
 a wire wound around the magnetically permeable material to form an inductive receiving coil 
 
 wherein the permanent magnet and the magnetically permeable material form a portion of a magnetic flux flow path that is configured to receive magnetic flux from the receptacle connector. 
 
     
     
       9. The electronic device of  claim 8 , wherein the permanent magnet is a first permanent magnet and the plug connector further comprises a second permanent magnet, the first permanent magnet located at a first distal tip of the magnetic permeable material, the second permanent magnet located at a second distal tip of the magnetically permeable material, the magnetically permeable material extending between the first and second permanent magnets. 
     
     
       10. The electronic device of  claim 9 , wherein the magnetic flux flow path is a circular magnetic flux flow path when the corresponding plug connector is mated with the receptacle connector. 
     
     
       11. The electronic device of  claim 8 , further comprising:
 a mating surface located adjacent to the magnetically permeable material, which forms a portion of an exterior surface of the electronic device and is configured to allow magnetic flux to flow to and from the corresponding plug connector when the corresponding plug connector is mated with the receptacle connector. 
 
     
     
       12. The electronic device of  claim 11 , wherein the mating surface is located at a recessed section of an external surface of the electronic device. 
     
     
       13. The electronic device of  claim 8 , further comprising a battery configured to receive electrical current from the inductive receiving coil. 
     
     
       14. The electronic device of  claim 8 , wherein the inductive receiving coil is formed in the shape of a half-toroid, and wherein the half-toroid includes curvatures extending in one or more planes. 
     
     
       15. A plug connector supporting inductive charging, the plug connector comprising:
 a housing having a mating end configured to mate with a corresponding receptacle connector, the housing comprising:
 first and second permanent magnets that cooperate to generate a magnetic field that attracts a corresponding receptacle connector of an electronic device and orients and aligns the plug connector therewith; 
 a magnetically permeable material that extends between the first and second permanent magnets; 
 an inductive transmission coil wound around the magnetically permeable material, wherein; and 
 an electrical connection coupled to the inductive transmission coil and configured to apply a current to the inductive transmission coil to induce a current in an inductive receiving coil of the corresponding connector; 
 
 wherein the first and second permanent magnets and the magnetically permeable material form a portion of a magnetic flux flow path when the electrical connection applies a current to the inductive transmission coil. 
 
     
     
       16. The plug connector of  claim 15 , wherein the magnetic flux flow path is a circular magnetic flux flow path when the plug connector is mated with the corresponding receptacle connector. 
     
     
       17. The plug connector of  claim 15 , wherein the mating end includes one or more magnetically permeable windows adjacent to the first and second permanent magnets. 
     
     
       18. The plug connector of  claim 15 , wherein a polarity of the first permanent magnet is oriented in a first direction and a polarity of the second permanent magnet is oriented in a second direction opposite the first direction. 
     
     
       19. The plug connector of  claim 15 , wherein the magnetic field maintains physical contact between the plug connector and the corresponding receptacle connector without the assistance of an interference fit between the plug connector and the corresponding receptacle connector. 
     
     
       20. The plug connector of  claim 15 , further comprising a cable coupled to the housing.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application No. 61/884,476, filed Sep. 30, 2013, which is hereby incorporated by reference for all purposes. 
    
    
     BACKGROUND 
     The present invention relates generally to inductive charging interfaces, and in particular inductive charging interfaces for mobile devices. 
     Many electronic devices mate with electrical connectors that provide power. For example, devices, such as tablets, laptops, netbooks, desktops, and all-in-one computers; cell, smart, and media phones; storage devices, portable media players, navigation systems, monitors, and others, can be mated with electrical connectors in order to charge their internal batteries. 
     Wired charging via electrical connectors (e.g., plug and receptacle connectors) is commonly used but wireless charging, and specifically inductive charging, is becoming increasingly common. However, while inductive charging is sometimes more convenient than wired charging, inductive charging historically has been very inefficient due to high energy losses, e.g., due to leakage flux, non-ideal magnetic paths, etc. These losses result in wasted resources as well as longer charge times as compared with wired charging. 
     Furthermore, in order to inductively charge electronic devices, large receiving coils are currently implemented within electronic devices. These receiving coils consume a significant amount of scarce space within increasingly compact electronic devices. A corresponding transmission coil is typically located within a charging pad to inductively charge these electronic devices when placed on the pad. 
     As electronic devices continue to consumer more power, there is an increasing demand for convenient, power-efficient and space-efficient methods of charging these electronic devices. 
     SUMMARY 
     Various embodiments of the invention pertain to an interface for high-efficiency inductive charging of electronic devices, including mobile electronic devices. Although some energy losses in inductive charging may be inherent and unavoidable, other losses caused by the misalignment of or large distance between receiving and transmission inductive charging elements can be reduced in embodiments of the present invention. 
     For example, a magnetic core of an inductive charging configuration may be divided into two magnetic elements; one element can be housed within a receptacle or receiving connector of a housing of an electric device and the other element can be housed within a plug or transmission connector. In some embodiments, these two elements can be shaped like U-shaped halves of a toroid. The poles of the two elements of the magnetic core may create a magnetic field to retain the plug connector in an aligned, mated position with the receptacle connector of the electronic device in addition to directing magnetic flux to flow in a circular path around and between the two elements of the magnetic core. Corresponding distal ends of the elements of the magnetic core may be in close proximity in the mated position, separated only by windows—thin pieces of magnetically permeable material. Additional elements corresponding to those of a typical transformer or inductive charger can also be included in this inductive charging configuration. 
     Instead of relying on the plug and receptacle connector of the present invention to provide data to electronic devices, wireless means such as Wi-Fi, other wireless protocols, and antenna coupling can be used to allow the electronic devices of the present invention to receive and send data. As such, accidental breakage that is common with conventional electrical connectors can be avoided via the breaking of magnetic retention instead of structural elements such as retention features or a connector housing. 
     Furthermore, as will be discussed in further detail below, the present invention may even allow for faster charging times due the higher charging efficiencies provided for in embodiments of the present invention. 
     According to one embodiment, a plug connector supporting inductive charging is provided. The plug connector can include a magnetic element having poles aligned to generate a magnetic field that attracts a corresponding receptacle connector of an electronic device and orients and aligns the plug connector therewith, a wire wound around the magnetic element to form an inductive transmission coil, an electrical connection coupled to the inductive transmission coil and configured to apply a current to the inductive transmission coil to induce a current in an inductive receiving coil of the corresponding receptacle connector and a magnetically permeable window adjacent to the magnetic element. The magnetically permeable window can form a portion of an exterior surface of the plug connector. The magnetically permeable window also can be configured to allow magnetic flux to flow to and from the corresponding receptacle connector when the corresponding receptacle connector is mated with the plug connector. 
     According to another embodiment, an electronic device that supports inductive charging is provided. The electronic device can include a receptacle connector having a mating surface configured to mate with a corresponding plug connector. The receptacle connector can include a magnetic element having poles positioned to generate a magnetic field that attracts a corresponding plug connector and orients and aligns the corresponding plug connector with the receptacle connector, and a wire wound around the magnetic element to form an inductive receiving coil. The mating surface can be located adjacent to the magnetic element, form a portion of an exterior surface of the electronic device and be configured to allow magnetic flux to flow to and from the corresponding plug connector when the corresponding plug connector is mated with the receptacle connector. The electronic device can also include a battery within the electronic device and a charging circuit within the electronic device. The charging circuit can be configured to use an induced current received from the inductive receiving coil to charge the battery. 
     According to yet another embodiment, a plug connector supporting inductive charging is provided. The plug connector can include a housing having a mating end configured to mate with a corresponding receptacle connector. The housing can include a magnetic element having poles aligned to generate a magnetic field that attracts a corresponding receptacle connector of an electronic device and orients and aligns the plug connector therewith, a wire wound around the magnetic element to form an inductive transmission coil and an electrical connection coupled to the inductive transmission coil and configured to apply a current to the inductive transmission coil to induce a current in a inductive receiving coil of the corresponding connector. The mating end can be further configured to allow magnetic flux to flow to and from the corresponding receptacle connector when the corresponding receptacle connector is mated with the plug connector. The plug connector can also include a cable coupled to the housing. 
     Although aspects of the invention are described in relation to plug and receptacle connectors for mobile devices and mobile device accessories, it is appreciated that these aspects and methods can be used in a variety of different environments such as larger or smaller electronic devices, e.g., electric vehicles and/or hearing aids. 
     To better understand the nature and advantages of the present invention, reference should be made to the following description and the accompanying figures. It is to be understood, however, that each of the figures is provided for the purpose of illustration only and is not intended as a definition of the limits of the scope of the present invention. Also, as a general rule, and unless it is evident to the contrary from the description, where elements in different figures use identical reference numbers, the elements are generally either identical or at least similar in function or purpose. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  depicts an illustrative rendering of one particular electronic device; 
         FIG. 1B  is a simplified perspective view of plug connector that can be mated with a corresponding primary receptacle connector of the device; 
         FIGS. 2A and 2B  illustrate simplified perspective and internal structure views of a device and a plug connector corresponding to a receptacle connector of the device, according to an embodiment of the present invention; 
         FIG. 3  illustrates a simplified perspective view of a device and a plug connector corresponding to a receptacle connector of the device, according to an embodiment of the present invention; 
         FIG. 4  illustrates a simplified perspective view of a device and a plug connector corresponding to a receptacle connector of the device, according to an embodiment of the present invention; 
         FIGS. 5A and 5B  illustrate simplified perspective and internal structure views of a device and a plug connector corresponding to a receptacle connector of the device, according to an embodiment of the present invention. 
         FIG. 6  illustrates a simplified perspective view of a device and a plug connector corresponding to a receptacle connector of the device, according to an embodiment of the present invention; 
         FIG. 7  illustrates a simplified perspective view of a device and a plug connector corresponding to a receptacle connector of the device, according to an embodiment of the present invention; and 
         FIG. 8  illustrates a simplified perspective view of the back side of a device, according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described in detail with reference to certain embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known details have not been described in detail in order not to unnecessarily obscure the present invention. 
     Embodiments of the present invention can provide for high efficiency inductive charging of mobile devices and accessories by facilitating the flow of magnetic flux along more optimal paths. For example, a magnetic core of an inductive charging configuration may be divided into two magnetic elements; one element can be housed within or near a receptacle or receiving connector of an electric device and the other element can be housed within or near a plug or transmission connector. When the plug and receptacle connectors are joined, the two magnetic elements may combine to form a closed magnetic flux path. The magnetic flux may travel in circular motion within and between the magnetic elements, as directed by the poles of the magnetic elements. Additional elements corresponding to those of a typical transformer or an inductive charger can also be included in this inductive charging configuration. 
     This closed flux path may limit losses that typically occur with open magnetic flux paths and increase the strength of the magnetic field between the magnetic elements. As such, in embodiments of the present invention, devices may receive around 90% of the power transmitted by corresponding plug connectors, i.e., 90% inductive charging efficiency may be achieved. The magnetic field may also serve to align the plug and receptacle connectors with respect to each other as well as to provide a retention force to hold the plug connector in a mated position with the receptacle connector. 
     Some embodiments can provide blind mating of the plug and receptacle connectors. That is, mating of the connectors may occur simply by bringing the connectors within proximity of each other. Magnetic forces may bring the connectors into physical contact with each other in the proper orientation and alignment. 
     Although the present invention is comparable with other inductive chargers configurations in terms of function, the present invention physically resembles current wired charging configurations. The following figure is an example of a wired charging configuration that may be useful in illustrating some of the advantages of the present invention. 
     I. Traditional Wired Interface 
       FIG. 1A  depicts an illustrative rendering of one particular electronic device  10 . Device  10  includes a touch screen display  20  as both an input and an output component housed within a device housing  30 . Device  10  also includes a primary receptacle connector  35  and an audio plug receptacle  40  within device housing  30 . Each of the receptacle connectors  35  and  40  can be positioned within housing  30  such that the cavity of the receptacle connector into which a corresponding plug connector is inserted can be located at an exterior surface of the device housing. The cavity can open to an exterior side surface of device  10 . For simplicity, various internal components, such as the control circuitry, graphics circuitry, bus, memory, storage device and other components are not shown in  FIG. 1A . 
       FIG. 1B  is a simplified perspective view of plug connector  100  that can be mated with a corresponding primary receptacle connector  35  of device  10  (shown in  FIG. 1A ). As shown in  FIG. 1B , plug connector  100  includes a body  42  and a tab or insertion end  44  that extends longitudinally away from body  42  in a direction parallel to the length of the connector. A cable  43  is attached to body  42  at an end opposite of insertion end  44 . 
     Insertion end  44  is sized to be inserted into corresponding receptacle connector  35  during a mating event and may include contacts (not shown) formed on a first major surface  44   a  and a second major surface  44   b  (not shown) opposite surface  44   a . Surfaces  44   a ,  44   b  extend from a distal tip or end of the insertion end to body  42 . When insertion end  44  is inserted into corresponding receptacle connector  35 , surfaces  44   a ,  44   b  abut a housing of receptacle connector  35  or device  10 . Insertion end  44  also includes first and second opposing side surfaces  44   c ,  44   d  (not shown) that extend between the first and second major surfaces  44   a ,  44   b . The contacts of connector  100  (not shown) can be used to carry a wide variety of signals including digital signals and analog signals as well as power and ground. 
     As illustrated and described above with reference to  FIGS. 1A and 1B , wired charging configurations can include numerous complex features on the plug as well as the receptacle connector side to accommodate wired charging, e.g., receptacle connector cavities, accommodations for exposed connector contacts, retention features, complex geometries and materials chosen to protect the connectors against accidental breakage. Inductive charging configuration may eliminate the necessity of all or some these wired charging features. 
     However, current methods of inductive charging are not without shortcomings. As mentioned above, in order to inductively charge electronic devices, receiving coils that consume a significant amount of scarce space within increasingly compact electronic devices are required and even then high energy losses, e.g., due leakage flux, non-ideal magnetic paths, etc., are likely to occur. For example, in inductive charging configurations, the charging pad and the mobile device include charging coils that are typically arranged in a planar spiral pattern, the coils being oriented in planes that are parallel to each other and separated by a distance, e.g., several millimeters. Magnetic flux may flow in two circular patterns between the charging coils and about a plane that is perpendicular to the planes in which the charging coils are oriented. These circular patterns may represent non-closed, non-ideal magnetic flux flow paths. 
     II. Inductive Charging Interface With Magnetic Retention 
     In contrast with the current methods of inductive charging briefly described above, the receiving and transmission coils of the present invention are wrapped around halves of a magnetic core, which halves guide the magnetic flux flow along a substantially closed flux flow path. One of the halves of the magnetic core can be located within each of the plug and receptacle connectors and can provide one or more magnetic flux flow paths or loops. The halves of the magnetic core also provide magnetic retention to hold a receiving or receptacle connector of a device and a plug connector in a mated position. The following figures illustrate examples of (A) a single loop inductive charging interface, (B) a multi-loop inductive charging interface and (C) a multi-planar loop inductive charging interface 
     A. Single Loop Inductive Charging Interface 
       FIGS. 2A and 2B  illustrate simplified perspective and internal structure views of a device  200  and a plug connector  202  corresponding to a receptacle connector  212  of device  200 , according to an embodiment of the present invention. As shown in  FIG. 2A , device  200  includes a receptacle connector  212  positioned within a housing  210  such that a mating surface  214  of receptacle connector  212  is disposed at an exterior of the device housing  210 . Mating surface  214  includes two magnetically permeable windows  216   a ,  216   b . The function of windows  216   a ,  216   b  will be described below with reference to  FIG. 2B . For simplicity, various internal components, such as the control circuitry, graphics circuitry, bus, memory, storage device and other components are not shown in  FIG. 2A . 
     As further shown in  FIG. 2A , plug connector  202  includes a body  218  having a mating end  220  and a cable  222  attached at an end opposite of mating end  220 . Mating end  220  is sized to interface with mating surface  214  of corresponding receptacle connector  212  during a mating event and includes first and second magnetically permeable windows  224   a ,  224   b . When plug connector  202  is mated with corresponding receptacle connector  212 , mating end  220  is brought into contact with mating surface  214  such that windows  224   a  and  224   b  can be aligned with and in contact with windows  216   a  and  216   b , respectively. 
     Windows  216   a ,  216   b ,  224   a  and  224   b  may be between about 2 mm and 7 mm tall, about 5 mm and 15 mm wide and about 0.25 mm and 0.5 mm thick, and may be made from a magnetically permeable material that is also electrically insulative, e.g., strong polymers, sapphire or other strong materials that are magnetically permeable and electrically insulative. As further described below, these magnetically permeable materials can allow magnetic flux to flow to and from the magnetic elements (as shown in  FIG. 2B ) and through the windows of plug connector  202  and receptacle connector  212 . In addition, the insulative properties of these materials may insulate magnetic flux from the housing  210 , which may be made from a metallic, conductive material that could cause losses during inductive charging if not insulated. The following figure illustrates how magnetic flux flows through windows  216   a ,  216   b ,  224   a  and  224   b  and between plug connector  202  and receptacle connector  212  during inductive charging. 
     Optionally, as shown in  FIG. 2B , plug connector  202  can include a transformer  226 . An inductive transmission coil  228  can be coupled to transformer  226  and wound around a first magnetic element  230 .  FIG. 2B  also shows that receptacle connector  212  includes a second magnetic element  232  and an inductive receiving coil  234  wound around second magnetic element  232 . Device  200  is also shown as including a charging circuit  236 , a battery  238  and internal components  240 . 
     First and second magnetic elements  230 ,  232  both include permanent magnets at their distal tips and a magnetically permeable material, e.g., a ferrite material such as iron, extending between the permanent magnets. More specifically, first magnetic element  230  includes first and second permanent magnets  240   a ,  240   b  and a ferrite material element  242  extending between the first and second permanent magnets  240   a ,  240   b . Similarly, second magnetic element  232  includes first and second permanent magnets  244   a ,  244   b  and a ferrite material element  246  extending between the first and second permanent magnets  244   a ,  244   b . As shown in  FIG. 2B , the poles of permanent magnets  244   a  and  244   b  are aligned to magnetically attract permanent magnets  240   a  and  240   b , respectively. First and second magnetic elements  230 ,  232  may each be U-shaped as shown in  FIG. 2B  or otherwise shaped, e.g., shaped like halves of a toroid—a half-toroid—or other shapes that would allow for magnetic flux to flow in a circular direction within first and second magnetic elements  230 ,  232 . First and second magnetic elements  230 ,  232  may function in a manner similar to magnetic, ferromagnetic or ferrite cores in traditional inductive charging configurations. 
     Device  200  may be inductively charged when plug connector  202  and receptacle connector  212  are mated, as shown in  FIG. 2B . During this inductive charging, cable  222  provides power to transformer  226  from a power source, e.g., a wall socket. Transformer  226  converts the power received from cable  222  as necessary and provides A/C power to transmission coil  228 . Alternatively, if plug connector  202  does not include transformer  226 , cable  222  can provide A/C power directly to transmission coil  228 . Transmission coil  228  can be wrapped around first magnetic element  230  of a magnetic core. As time-varying current flows through transmission coil  228 , a varying magnetic flux  248  can be created and may flow within and between first and second magnetic elements  230 ,  234 . Magnetic flux  248  travels between first and second magnetic elements  230 ,  232  via magnetically permeable windows  216   a ,  216   b ,  224   a  and  224   b . Thus, the first and second magnetic elements  230 ,  232  may form portions of a substantially closed flux flow path for varying magnetic flux  248 , i.e., varying magnetic flux  248  may flow substantially within first and second magnetic elements  230 ,  232 , as guided by the polarity of permanent magnets  240   a ,  240   b ,  244   a  and  244   b.    
     Magnetic flux  248  can create a time-varying magnetic field that travels through a receiving coil  234  of receptacle connector  212 , thereby inducing a time-varying current in receiving coil  234 . As shown in  FIG. 2B , a charging circuit  236  is coupled to receiving coil  234 . As such, the induced current can be provided to and used by charging circuit  236  to charge a battery  238  that powers internal components  240  of device  200 , e.g., control circuitry, graphics circuitry, bus, memory, storage device and other components. In this manner, an electrical connection, e.g., cable  222  or transformer  226 , may apply a current to inductive transmission coil  228  in order to induce a current in inductive receiving coil  234  and charge device  200 . 
     As mentioned above, the poles of permanent magnets  244   a  and  244   b  are aligned to magnetically attract permanent magnets  240   a  and  240   b , respectively. As such, when plug connector  202  is sufficiently proximate receptacle connector  212 , magnetic forces will bring plug connector  202  into contact with receptacle connector  212 , as shown in  FIG. 2B . For example, the magnetic forces may rotate plug connector  202  about its longitudinal axis and translate plug connector  202  in the vertical and/or horizontal directions until orientated and aligned with respect to receptacle connector  212  as shown in  FIG. 2B . Additionally, once mated, the magnetic forces can provide a retention force to retain or hold plug connector  202  in contact with receptacle connector  212  in the mated position. The size and/or strength of permanent magnets  244   a ,  244   b ,  240   a  and  240   b  may be varied to adjust the retention force and the proximity between plug connector  202  and receptacle connector  212  required for plug connector  202  to be oriented, aligned and brought into contact with receptacle connector  212 . Thus, an interference fit between receptacle connector  212  and plug connector  202  may not be required, and the retention features outlined above with reference to  FIGS. 1A-1B  may also not be required. 
     Additional magnets may be included in plug connector  202  and/or receptacle connector  212  to provide to an increased magnetic retention force. For example, as shown in  FIG. 2B , plug connector  202  may include permanent magnets  250   a ,  250   b ,  250   c  and receptacle connector  212  may include permanent magnets  252   a ,  252   b ,  252   c . The poles of permanent magnets  250   a ,  250   b ,  250   c ,  252   a ,  252   b  and  252   c  may be aligned as shown in  FIG. 2B  or otherwise aligned such that an additional magnetic force is created between plug connector  202  and receptacle connector  212  to provide magnetic retention. The additional magnets may be electrically isolated, e.g., surrounded by an insulative material such as a polymer, to minimize interference experienced by magnetic flux  248 . The number of additional magnets may be varied, e.g., more or less permanent magnets may be implemented in plug connector  202  and receptacle connector  212 . 
     As also mentioned above, the first and second magnetic elements  230 ,  232  may form portions of a substantially closed flux flow path. The flux flow path between first and second magnetic elements  230 ,  232  may be substantially closed rather than completely closed because the thickness of windows  216   a ,  216   b ,  224   a  and  224   b  create small gaps between the first and second magnetic elements  230 ,  232 . These gaps between corresponding distal tips of the first and second magnetic elements  230 ,  232  may be, for example, between about 0.5 mm and 1.0 mm or between about 0.2 mm and 1.2 mm. Losses may occur at these gaps because the magnetic flux is not travelling about a closed path when crossing the gap, thereby allowing some magnetic flux to flow away from first and second magnetic elements  230 ,  232 . Reducing this gap may increase the inductive charging efficiency of the invention, and may be accomplished by reducing the thickness of windows  216   a ,  216   b ,  224   a  and  224   b.    
     However, reducing this thickness or eliminating these widows entirely may pose other challenges because permanent magnets, as well as other types of magnets, may be prone to corrosion and/or scratching if left exposed by plug and receptacle connectors. Accordingly, windows  216   a ,  216   b ,  224   a  and  224   b  are provided to protect the distal tips of first and second magnetic elements  230 ,  232 , whether they be permanent magnets or otherwise. Suitable materials such as strong polymers, sapphire, other strong materials that are magnetically permeable or a combination thereof may be used to form windows  216   a ,  216   b ,  224   a  and  224   b . Windows  216   a ,  216   b ,  224   a  and  224   b  may be discrete elements having dimensions as outlined above or they may be exposed portions of a larger element or elements, e.g., they may be integrally formed with a housing of receptacle connector  212 . 
     The inductive charging interface with magnetic retention as outlined above possesses numerous advantages over traditional wired and wireless charging interfaces. For example, many traditional wired charging interfaces include receptacle connector having an opening that can collect debris. Debris can create interfere with power and data transfer between plug and receptacle connectors. Conversely, receptacle connector  212  may include a flat mating surface  214  that interfaces with a mating end  220  of plug connector  202 , thereby eliminating connector openings and the potential for debris buildup within connector openings. Additionally, the magnetic field generated by plug connector  202  may rotate and translate plug connector  202  as necessary to properly connect, orient and align it with receptacle connector  212 , thereby to preventing losses and providing a more efficient magnetic flux flow. This magnetic field, in combination with a minimal gap provided between first and second magnetic elements  230 ,  232 , can allow the present invention to achieve inductive charging efficiency that may exceed that of traditional inductive charging methods. 
     Although device  200  is shown and described as one particular electronic media device, embodiments of the invention are suitable for use with a multiplicity of electronic devices. For example, any device that receives or transmits audio, video or data signals may include the invention. These devices can a multipurpose button as an input component, a touch screen display as both an input and an output component, and a speaker as an output component, all of which can be housed within a device housing that can be made from a metallic material. 
     As used herein, the term “electronic device” or “device” can include any device with at least one electronic component that may be used to present human-perceivable media. In some instances, embodiments of the invention are particularly well suited for use with electronic media devices because they often include a rechargeable battery. Such devices may include, for example, portable music players (e.g., MP3 devices and Apple&#39;s iPod devices), portable video players (e.g., portable DVD players), cellular telephones (e.g., smart telephones such as Apple&#39;s iPhone devices), wearable devices such as smartwatches, video cameras, digital still cameras, projection systems (e.g., holographic projection systems), gaming systems, PDAs, desktop computers, as well as tablet (e.g., Apple&#39;s iPad devices), laptop or other mobile computers. Other examples of electronic devices include docking stations, chargers, an external power source such as an external battery, cable adapters, clock radios, game controllers, audio equipment, headsets or earphones, video equipment and adapters, keyboards, medical sensor devices such as heart rate monitors and blood pressure monitors, point of sale (POS) terminals, as well as numerous other hardware devices that can connect to and exchange data with a host device. 
     In one embodiment, plug connector  202  can be the plug connector of a plug connector/receptacle connector interface that can be the primary physical connector system for an ecosystem of products that includes both host electronic devices and accessory devices. Examples of host devices include smart phones, portable media players, tablet computers, laptop computers, desktop computers and other computing devices. An accessory can be any piece of hardware that connects to and communicates with or otherwise expands the functionality of the host. Many different types of accessory devices can be specifically designed or adapted to receive power from plug connector  202  and to provide additional functionality for the host. Although plug connector  202  is only described above as providing power, embodiments of the present invention include data contacts on plug  202  and corresponding contacts on receptacle connector  212 . 
     Plug connector  202  can be incorporated into each accessory device that is part of the ecosystem to enable the host to provide power to plug connector  202  when the accessory is mated with a corresponding receptacle connector of the host device. Examples of accessory devices include docking stations, charge cables and devices, cable adapters, clock radios, game controllers, audio equipment, headsets, video equipment and adapters, keyboards, medical sensors such as heart rate monitors and blood pressure monitors, point of sale (POS) terminals, as well as numerous other hardware devices that can connect to and exchange data with the host device. Various wireless communication protocols may be used to communicate data between the host device and the accessory. 
     It will also be appreciated that the device  200  and plug connector  202  described above are illustrative and that various modifications are possible. For instance, although plug connector  202  is shown in  FIG. 2A  as having a rounded rectangular shape with a thickness, plug connector  202  may be spherically shaped, have a non-constant thickness and/or width, or be otherwise shaped in other embodiments. As another example, device housing  210  may be made from a non-metallic material, e.g., a polymer or other non-conductive materials. In embodiments where housing  210  is made from a non-conducive material, windows  216   a  and  216   b  may be made from the same material as housing  210  or may be integrally formed with housing  210 . Windows  224   a  and  224   b  may also be made from material different than that of base  218  or may be integrally formed with base  218 . 
     In some embodiments, first and second magnetic elements  230 ,  232  may be horseshoe magnets. Alternatively, permanent magnets  244   a ,  244   b ,  240   a  and  240   b  may be replaced with ferromagnetic materials capable of magnetic attraction, rare-earth magnets, or other materials capable of substantially maintaining plug connector  202  and corresponding receptacle connector  212  in a mated position using magnetic forces. 
     In some embodiments, one or more windows  216   a  and  216   b  and  224   a  and  224   b  may be located differently on receptacle connector  212  and plug connector  202 , respectively, than as shown in  FIG. 2A . For example, these windows may be located on any one or more of front, back, left, right, or top surfaces of device  200  and plug connector  202 . Furthermore, first and second magnetic elements  230 ,  232  (or variations thereof as described herein) may be disposed within the plug and receptacle connectors, respectively, and adjacent to magnetically permeable windows, e.g., the distal tips of first and second magnetic elements  230 ,  232  are positioned with respect to magnetically permeable windows as shown in  FIG. 2B . Additionally, the magnetically permeable windows of the receptacle connector  212  may be located in a recessed section of housing  210 . Examples of additional magnetically permeable window variations are illustrated in the following figures. 
     1. Unitary Magnetically Permeable Window 
       FIG. 3  illustrates a simplified perspective view of a device  300  and a plug connector  302  corresponding to a receptacle connector  312  of device  300 , according to an embodiment of the present invention. Device  300  and plug connector  302  may be similar to device  200  and plug connector  202 , respectively, except that they each include a single or unitary magnetically permeable window, instead of two windows. As shown in  FIG. 3 , Device  300  includes a receptacle connector  312  positioned within housing  310  such that a magnetically permeable window  316 , which may be a surface that contacts corresponding plug connectors during charging, of receptacle connector  312  is disposed at an exterior of the device housing  310 . The function of window  316  may be similar to that of windows  216   a ,  216   b  (shown in  FIGS. 2A and 2B ). For simplicity, various internal components, such as the control circuitry, graphics circuitry, bus, memory, storage device and other components are not shown in  FIG. 3 . 
     As further shown in  FIG. 3 , plug connector  302  includes a body  318  having a magnetically permeable window  324  and a cable  322  attached at an end opposite the magnetically permeable window  324 . Magnetically permeable window  324  is sized to interface with magnetically permeable window  316  of corresponding receptacle connector  312  during a mating event. When plug connector  302  is mated with corresponding receptacle connector  312 , magnetically permeable window  324  is brought into contact with magnetically permeable window  316  such that magnetically permeable window  324  can be aligned with, i.e., centered over, magnetically permeable window  316 . 
     Windows  316  and  324  may be between about 2 mm and 7 mm tall, about 15 mm and 45 mm wide and about 0.25 mm and 0.5 mm thick, and may be made from a magnetically permeable material that is also electrically insulative, e.g., strong polymers, sapphire or other strong materials that are magnetically permeable and electrically insulative. As further described above with reference to  FIG. 2B , these magnetically permeable materials can allow magnetic flux to flow to and from the magnetic elements (as shown in  FIG. 2B ) and through the windows  316  and  324 . In addition, the insulative properties of these materials may insulate magnetic flux from the housing  310 , which may be made from a metallic, conductive material that could cause losses during inductive charging if not insulated. Similar to the function provided by windows  216   a ,  216   b ,  224   a  and  224   b , windows  316  and  324  allow magnetic flux to flow between plug connector  302  and receptacle connector  312  during inductive charging. 
     Again, device  300  and plug connector  302  may be similar in function as form to device  200  and plug connector  202 , respectively, except that they each include a unitary magnetically permeable window (e.g., windows  316  and  324 ), instead of two windows. More specifically, the internal elements and variations thereof discussed with reference to  FIG. 2B  may also be included in device  300  and plug connector  302 . Furthermore, device  300  and plug connector  302  may function in a manner similar to device  200  and plug connector  202 , which manner and variations thereof were described above with reference to  FIG. 2B . However, instead of having magnetic flux flow into some windows and out of others as with device  200  and plug connector  202 , magnetic flux flows both into and out of each of windows  316  and  324 . 
     Accordingly, plug connector  302  may be used to inductively charge device  300 , and this charging configuration may realize advantages discussed with reference to  FIG. 2B . Implementing unitary magnetically permeable windows may provide additional advantage in some situations, e.g., reducing part count may simplify the manufacturing/assembly process of device  300  and plug connector  302  and/or provide a different aesthetic appearance. 
     In some embodiments, one of plug connector  302  and receptacle connector  312  may include a unitary magnetically permeable window while the other connector may include two magnetically permeable windows, e.g., windows  216   a ,  216   b  or windows  224   a  and  224   b . Examples of yet additional window variations are illustrated in the following figures. 
     2. Magnetically Permeable Window Frames 
       FIG. 4  illustrates a simplified perspective view of a device  400  and a plug connector  402  corresponding to a receptacle connector  412  of device  400 , according to an embodiment of the present invention. Device  400  and plug connector  402  may be similar to device  200  and plug connector  202 , respectively, except that they each include two magnetically permeable window frames that circumscribe distal tips of magnet elements, instead of two windows covering distal tips of magnetic elements. In addition, the receptacle connector of device  400  (e.g., receptacle connector  412 ) can be located at a different position than that of device  200 . 
     As shown in  FIG. 4 , device  400  includes a receptacle connector  412  positioned within housing  410  such that a mating surface  414  of receptacle connector  412  is disposed at an exterior of the device housing  410 . Mating surface  414  includes two magnetically permeable window frames  416   a ,  416   b  that frame or circumscribe permanent magnets  444   a ,  444   b  of a first magnetic element (not shown, but see, e.g., magnetic element  232  in  FIG. 2B ). The function of window frames  416   a ,  416   b  may be similar to that of windows  216   a ,  216   b  (shown in  FIGS. 2A and 2B ) to the extent that windows  216   a ,  216   b  provide shielding for magnetic flux from potential interference caused by housing  210 ; however, only incidental magnetic flux may flow through window frames  416   a ,  416   b . Instead, magnetic flux may flow directly from exposed distal tips of permanent magnets  444   a ,  444   b  to corresponding distal tips of permanent magnets  440   a ,  440   b  of a second magnetic element (not shown, but see, e.g., magnetic element  230  in  FIG. 2B ) of plug connector  402 . For simplicity, various internal components, such as the control circuitry, graphics circuitry, bus, memory, storage device and other components are not shown in  FIG. 4 . 
     As further shown in  FIG. 4 , plug connector  402  includes a body  418  having a mating end  420  and a cable  422  attached at an end opposite of mating end  420 . Mating end  420  is sized to interface with mating surface  414  of corresponding receptacle connector  412  during a mating event and includes first and second magnetically permeable window frames  424   a ,  424   b  that frame or circumscribe distal tips of permanent magnets  440   a ,  440   b . When plug connector  402  is mated with corresponding receptacle connector  412 , mating end  420  is brought into contact with mating surface  414  such that permanent magnets  440   a  and  440   b  can be aligned with, i.e., centered over, and in contact with permanent magnets  444   a  and  444   b , respectively. 
     Window frames  416   a ,  416   b ,  424   a  and  424   b  may be between about 2 mm and 7 mm tall, about 5 mm and 15 mm wide and about 0.25 mm and 0.5 mm thick and may include an opening for receiving distal ends of permanent magnets  440   a ,  440   b ,  444   a  and  444   b . The frames may be made from a magnetically permeable material that is also electrically insulative, e.g., strong polymers, sapphire or other strong materials that are magnetically permeable and electrically insulative. As further described above with reference to  FIG. 2B , the insulative properties of these materials may insulate magnetic flux from the housing  410 , which may be made from a metallic, conductive material that could cause losses during inductive charging if not insulated. 
     As mentioned above, in contrast with the embodiments described with reference to  FIGS. 2A, 2B and 3 , magnetic flux may flow directly between permanent magnets  440   a  and  444   a  and between permanent magnets  440   b  and  444   b  during inductive charging, without passing through a window (e.g., windows  216   a ,  216   b ,  224   a  and  224   b ). Nonetheless, the internal elements and variations thereof discussed with reference to  FIG. 2B  may also be included in device  400  and plug connector  402 . Furthermore, aside from the differences described, device  400  and plug connector  402  may function in a manner similar to device  200  and plug connector  202 , which manner and variations thereof were described above with reference to  FIG. 2B . 
     Accordingly, plug connector  402  may be used to inductively charge device  400 , and this charging configuration may realize advantages discussed with reference to  FIG. 2B . In addition, the gaps between permanent magnets  444   a  and  440   a  and permanent magnets  440   b  and  444   b  may be smaller as compared to other embodiments discussed above because windows (e.g., windows  216   a ,  216   b ,  224   a  and  224   b ) are not disposed between these magnets. As such, the distance or gap between permanent magnets  444   a  and  440   a  and permanent magnets  440   b  and  444   b  may be less than about 0.2 mm. Thus, the magnetic flux flow path between device  400  and plug connector  402  may be closed or nearly closed, charging losses may be reduced and inductive charging efficiency may be increased. 
     It will also be appreciated that device  200  and plug connector  202  described above are illustrative and that various modifications are possible. For instance, the exposed ends of permanent magnets  440   a ,  440   b ,  444   a  and  444   b  may still be otherwise protected from corrosion and scratching, e.g., using a coating, plating and/or an air gap smaller than the window material gap, instead of including magnetically permeable windows that cover the exposed ends of permanent magnets  440   a ,  440   b ,  444   a  and  444   b . As another example, one of plug connector  402  and receptacle connector  412  may include a unitary magnetically permeable window, e.g., windows  316  and  324 , while the other connector includes two magnetically permeable windows, e.g., windows  216   a ,  216   b  or windows  224   a  and  224   b . Plug connector  402  and receptacle connector  412  may also each include a combination of window frames and windows. 
       FIGS. 2A, 2B, 3 and 4  all illustrate embodiments of the present invention that include a single circular magnetic flux path or loop where halves of a magnetic core, e.g., first and second magnetic elements, can be located within plug and receptacle connectors. Examples of additional embodiments that include more than one magnetic flux path or loop are illustrated in the following figures. 
     B. Multi-Loop Inductive Charging Interface 
       FIGS. 5A and 5B  illustrate simplified perspective and internal structure views of a device  500  and a plug connector  502  corresponding to a receptacle connector  512  of device  500 , according to an embodiment of the present invention. Device  500  and plug connector  502  may be similar to device  200  and plug connector  202  (as shown in  FIGS. 2A and 2B ), respectively, except that they each include E-shaped first and second magnetic elements, instead of U-shaped first and second magnetic elements (e.g., magnetic elements  230 ,  232  as shown in  FIG. 2B ). Yet, these E-shaped first and second magnetic elements may also facilitate inductive charging. More specifically, these halves of a magnetic core may guide magnetic flux flow along two substantially closed flux flow paths during inductive charging. 
     As shown in  FIG. 5A , device  500  includes a receptacle connector  512  positioned within housing  510  such that a mating surface  514  of receptacle connector  512  is disposed at an exterior of the device housing  510 . Mating surface  514  includes first, second and third magnetically permeable windows  516   a ,  516   b , and  516   c . The function of windows  516   a ,  516   b ,  516   c  will be described below with reference to  FIG. 5B . For simplicity, various internal components, such as the control circuitry, graphics circuitry, bus, memory, storage device and other components are not shown in  FIG. 5A . 
     As further shown in  FIG. 5A , plug connector  502  includes a body  518  having a mating end  520  and a cable  522  attached at an end opposite of mating end  520 . Mating end  520  is sized to interface with mating surface  514  of corresponding receptacle connector  512  during a mating event and includes first, second and third magnetically permeable windows  524   a ,  524   b ,  524   c . When plug connector  502  is mated with corresponding receptacle connector  512 , mating end  520  is brought into contact with mating surface  514  such that windows  524   a ,  524   b  and  524   c  can be aligned with, i.e., centered over, and in contact with windows  516   a ,  516   b , and  516   c , respectively. 
     Windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b , and  524   c  may each be between about 2 mm and 7 mm tall, about 5 mm and 15 mm wide and about 0.25 mm and 0.5 mm thick, and may be made from a magnetically permeable material that is also electrically insulative, e.g., strong polymers, sapphire or other strong materials that are magnetically permeable and electrically insulative. As further described below, these magnetically permeable materials can allow magnetic flux to flow to and from magnetic elements (as shown in  FIG. 5B ) and through the windows of plug connector  502  and receptacle connector  512 . In addition, the insulative properties of these materials may insulate magnetic flux from the housing  510 , which may be made from a metallic, conductive material that could cause losses during inductive charging if not insulated. The following figure illustrates how magnetic flux flows through windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b , and  524   c  and between plug connector  502  and receptacle connector  512  during inductive charging. 
     Optionally, as shown in  FIG. 5B , plug connector  502  can include a transformer  526 . First and second inductive transmission coils  528   a ,  528   b  can be coupled to transformer  526  and wound around a first magnetic element  530 .  FIG. 5B  also shows that receptacle connector  512  includes a second magnetic element  532  and first and second inductive receiving coils  534   a ,  534   b  wound around second magnetic element  532 . Device  500  is also shown as including a charging circuit  536 , a battery  538  and internal components  540 . 
     First and second magnetic elements  530 ,  532  both include permanent magnets at their distal tips and a magnetically permeable material, e.g., a ferrite material such as iron, extending between the permanent magnets. More specifically, first magnetic element  530  includes first, second and third permanent magnets  540   a ,  540   b  and  540   c  and a ferrite material element  542  extending between the first, second third permanent magnets  540   a ,  540   b  and  540   c . Similarly, second magnetic element  532  includes first, second and third permanent magnets  544   a ,  544   b  and  544   c  and a ferrite material element  546  extending between first, second and third permanent magnets  544   a ,  544   b  and  544   c . As shown in  FIG. 5B , the poles of permanent magnets  544   a ,  544   b  and  544   c  are aligned to magnetically attract permanent magnets  540   a ,  540   b  and  540   c , respectively. First and second magnetic elements  530 ,  532  may each be E-shaped as shown in  FIG. 5B  or otherwise shaped, e.g., shaped liked halves of a toroid—a half-toroid—or other shapes that would allow for magnetic flux to flow in a circular directions within the first second magnetic elements  530 ,  532 . First and second magnetic elements  530 ,  532  may function in a manner similar to magnetic or ferromagnetic cores in traditional inductive charging configurations. 
     Device  500  may be inductively charged when plug connector  502  and receptacle connector  512  are mated, as shown in  FIG. 5B . During this inductive charging, cable  522  provides power to transformer  526  from a power source, e.g., a wall socket. Transformer  526  converts the power received from cable  522  as necessary and provides A/C power to transmission coils  528   a ,  528   b . Alternatively, if plug connector  502  does not include transformer  526 , cable  522  can provide A/C power directly to transmission coils  528   a ,  528   b . Transmission coils  528   a ,  528   b  can be wrapped around first magnetic element  530  of a magnetic core. As time-varying current flows through transmission coils  528   a ,  528   b , varying first and second magnetic fluxes  548   a ,  548   b  can be created and may flow within and between first and second magnetic elements  530 ,  534 . First magnetic flux  548   a  travels between first and second magnetic elements  530 ,  532  via magnetically permeable windows  516   a ,  516   b ,  524   a  and  524   b . Second magnetic flux  548   b  travels between first and second magnetic elements  530 ,  532  via magnetically permeable windows  516   b ,  516   c ,  524   b  and  524   c . Thus, the first and second magnetic elements  530 ,  532  may form portions of two substantially closed flux flow paths for varying magnetic fluxes  548   a ,  548   b , i.e., varying magnetic fluxes  548   a ,  548   b  may flow substantially within first and second magnetic elements  530 ,  532 , as guided by the polarity of permanent magnets  540   a ,  540   b ,  540   c ,  544   a ,  544   b  and  544   c.    
     Magnetic fluxes  548   a ,  548   b  can create time-varying magnetic fields that travel through first and second receiving coils  534   a ,  534   b  of receptacle connector  512 , thereby inducing a time-varying current in receiving coils  534   a ,  534   b . As shown in  FIG. 5B , a charging circuit  536  is coupled to receiving coils  534   a ,  534   b . As such, the induced currents can be provided to and used by charging circuit  536  to charge a battery  538  that powers internal components  540  of device  500 , e.g., control circuitry, graphics circuitry, bus, memory, storage device and other components. In this manner, an electrical connection, e.g., cable  522  or transformer  526 , may apply a current to inductive transmission coils  528   a ,  528   b  in order to induce a current in inductive receiving coils  234   a ,  234   b  and charge device  200 . 
     As mentioned above, the poles of permanent magnets  540   a ,  540   b  and  540   c  are aligned to magnetically attract permanent magnets  544   a ,  544   b  and  544   c , respectively. As such, when plug connector  502  is sufficiently proximate receptacle connector  512 , magnetic forces will bring plug connector  502  into contact with receptacle connector  512 , as shown in  FIG. 5B . For example, the magnetic forces may rotate plug connector  502  about its longitudinal axis and translate plug connector  502  in the vertical and/or horizontal directions until orientated and aligned with respect to receptacle connector  512  as shown in  FIG. 5B . Additionally, once mated, the magnetic forces can provide a retention force to retain or hold plug connector  502  in contact with receptacle connector  512  in the mated position. The size and/or strength of permanent magnets  540   a ,  540   b ,  540   c ,  544   a ,  544   b  and  544   c  may be varied to adjust the retention force and the proximity between plug connector  502  and receptacle connector  512  required for plug connector  502  to be oriented, aligned and brought into contact with receptacle connector  512 . Thus, an interference fit between receptacle connector  512  and plug connector  202  may not be required, and the retention features outlined above with reference to  FIGS. 1A-1B  may also not be required. 
     Additional magnets may be included in plug connector  502  and/or receptacle connector  512  to provide an increased magnetic retention force. For example, as shown in  FIG. 5B , plug connector  502  may include permanent magnets  550   a  and  550   b  and receptacle connector  512  may include permanent magnets  552   a  and  552   b . The poles of permanent magnets  550   a ,  550   b ,  552   a  and  552   b  may be aligned as shown in  FIG. 5B  or otherwise aligned such that an additional magnetic force is created between plug connector  502  and receptacle connector  512  to provide magnetic retention. The additional magnets may be electrically isolated, e.g., surrounded by an insulative material such as a polymer, to minimize interference experienced by magnetic flux  248 . The number of additional magnets may be varied, e.g., more or less permanent magnets may be implemented in plug connector  502  and receptacle connector  512 . 
     As also mentioned above, the first and second magnetic elements  530 ,  532  may form portions of substantially closed flux flow paths. The flux flow paths between first and second magnetic elements  530 ,  532  may be substantially closed rather than completely closed because the thickness of windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b  and  524   c  create small gaps between the first and second magnetic elements  530 ,  532 . These gaps between corresponding distal tips of the first and second magnetic elements  530 ,  532  may be, for example, between about 0.5 mm and 1.0 mm or between about 0.2 mm and 1.2 mm. Losses may occur at these gaps because the magnetic flux is not travelling about a closed path when crossing the gap, thereby allowing some magnetic flux to flow away from first and second magnetic elements  530 ,  532 . Reducing this gap may increase the inductive charging efficiency of the invention, and may be accomplished by reducing the thickness of windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b  and  524   c.    
     However, reducing this thickness or eliminating these widows entirely may pose other challenges because permanent magnets, as well as other types of magnets, may be prone to corrosion and/or scratching if left exposed by plug and receptacle connectors. Accordingly, windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b  and  524   c  are provided to protect the distal tips of first and second magnetic elements  530 ,  532 , whether they be permanent magnets or otherwise. Suitable materials such as strong polymers, sapphire, other strong materials that are magnetically permeable or a combination thereof may be used to form windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b  and  524   c . Windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b  and  524   c  may be discrete elements having dimensions as outlined above or they may be exposed portions of a larger element or elements, e.g., they may be integrally formed with a housing of receptacle connector  512 . 
     The inductive charging interface with magnetic retention as outlined above possesses numerous advantages over traditional wired and wireless charging interfaces. For example, many traditional wired charging interfaces include a receptacle connector having an opening that can collect debris. Debris can create interfere with power and data transfer between plug and receptacle connectors. Conversely, receptacle connector  512  may include a flat mating surface  514  that interfaces with a mating end  520  of plug connector  502 , thereby eliminating connector openings and the potential for debris buildup within connector openings. Additionally, the magnetic field generated by plug connector  502  may rotate and translate plug connector  502  as necessary to properly connect, orient and align with receptacle connector  512  to prevent losses and provide a more efficient magnetic flux flow. This magnetic field, in combination with a minimal gap provided between first and second magnetic elements  530 ,  532 , can allow the present invention to achieve inductive charging efficiency that may exceed that of traditional inductive charging methods. 
     In addition, plug connector  502  may be reversible, i.e., it may be connected with receptacle connector  512  in either of two orientations that differ by 180°. For example, in addition to the orientation shown in  FIG. 5B , plug connector  502  may also be mated with receptacle connector  512  when rotated 180°, as compared to the orientation shown in  FIG. 5B , about its longitudinal axis. In either of these two orientations, the poles of the magnets of plug connector  502  and receptacle connector  512  may be properly aligned to allow for mating. 
     It will also be appreciated that the device  500  and plug connector  502  described above are illustrative and that various modifications are possible. For instance, although plug connector  502  is shown in  FIG. 5A  as having a rounded rectangular shape with a thickness, plug connector  502  may be spherically shaped, have a non-constant thickness and/or width, or may be otherwise shaped in other embodiments. As another example, the magnetic elements of the magnetic core may be formed to create more than two loops, e.g., three or four loops, and complementing elements could be scaled and/or modified as necessary to support additional loops for inductive charging. As yet another example, device housing  510  may be made from a non-metallic material, e.g., a polymer or other non-conductive materials. In embodiments where housing  510  is made from a non-conducive material, windows  516   a ,  516   b  and  516   c  may be made from the same material as housing  510  or may be integrally formed with housing  510 . Windows  524   a ,  524   b  and  524   c  may also be made from different material than that of base  518  or may be integrally formed with base  518 . 
     In some embodiments, first and second magnetic elements  530 ,  532  may be horseshoe magnets. Alternatively, permanent magnets  544   a ,  544   b ,  544   c ,  540   a ,  540   b  and  540   c  may be replaced with ferromagnetic materials capable of magnetic attraction, rare-earth magnets, or other materials capable of substantially maintaining plug connector  502  and corresponding receptacle connector  512  in a mated position using magnetic forces. 
     In some embodiments, one or more windows  516   a ,  516   b  and  516   c  and  524   a ,  524   b  and  524   c  may be located on different surfaces of receptacle connector  512  and plug connector  502 , respectively, than shown in  FIG. 5A . For example, these windows may be located on any one or more of front, back, left, right, or top surfaces of device  500  and plug connector  202 . And first and second magnetic elements  530 ,  532  (or variations thereof as described herein) may be disposed within the plug and receptacle connectors, respectively, and adjacent to a magnetically permeable window, e.g., the distal tips of first and second magnetic elements  530 ,  532  are positioned with respect to magnetically permeable windows as shown in  FIG. 5B . Additionally, the magnetically permeable windows of the receptacle connector  512  may be located in a recessed section of housing  510 . Examples of additional magnetically permeable window variations are illustrated in the following figures. 
     1. Unitary Magnetically Permeable Window 
       FIG. 6  illustrates a simplified perspective view of a device  600  and a plug connector  602  corresponding to a receptacle connector  612  of device  600 , according to an embodiment of the present invention. Device  600  and plug connector  602  may be similar to device  500  and plug connector  502 , respectively, except that they each include a single or unitary magnetically permeable window, instead of two windows; similar to the differences between device  200  and plug  202  and device  300  and plug  302 , respectively. Accordingly, the description above concerning how device  300  and plug  302  may vary from device  200  and plug  202 , respectively, may also apply here as it pertains to how device  600  and plug connector  602  may differ from device  500  and plug connector  502 , respectively. 
     As shown in  FIG. 6 , device  600  includes a receptacle connector  612  positioned within housing  610  such that a magnetically permeable window  616 , which may be a surface that contacts corresponding plug connectors during charging, of receptacle connector  612  is disposed at an exterior of the device housing  610 . The function of window  616  may be similar to that of windows  516   a ,  516   b  and  516   c  (shown in  FIGS. 5A and 5B ). For simplicity, various internal components, such as the control circuitry, graphics circuitry, bus, memory, storage device and other components are not shown in  FIG. 6 . 
     As further shown in  FIG. 6 , plug connector  602  includes a body  618  having a magnetically permeable window  624  and a cable  622  attached at an end opposite the magnetically permeable window  624 . Magnetically permeable window  624  is sized to interface with magnetically permeable window  616  of corresponding receptacle connector  612  during a mating event. When plug connector  602  is mated with corresponding receptacle connector  612 , magnetically permeable window  624  is brought into contact with magnetically permeable window  616  such that magnetically permeable window  624  can be aligned with, i.e., centered over, magnetically permeable window  616 . 
     Windows  616  and  624  may be between about 2 mm and 7 mm tall, about 15 mm and 45 mm wide and about 0.25 mm and 0.5 mm thick, and may be made from a magnetically permeable material that is also electrically insulative, e.g., strong polymers, sapphire or other strong materials that are magnetically permeable and electrically insulative. As further described above with reference to  FIG. 5B , these magnetically permeable materials can allow magnetic flux to flow to and from the magnetic elements (as shown in  FIG. 5B ) and through the windows  616  and  624 . In addition, the insulative properties of these materials may insulate magnetic flux from the housing  610 , which may be made from a metallic, conductive material that could cause losses during inductive charging if not insulated. Similar to the function provided by windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b  and  524   c , windows  616  and  624  allow magnetic flux to flow between plug connector  602  and receptacle connector  612  during inductive charging. 
     Again, device  600  and plug connector  602  may be similar to device  500  and plug connector  502 , respectively, in function and form except that they each include a unitary magnetically permeable window (e.g., windows  616  and  624 ), instead of two windows. More specifically, the internal elements and variations thereof discussed with reference to  FIG. 5B  may also be included in device  600  and plug connector  602 . Furthermore, device  600  and plug connector  602  may function in a manner similar to device  500  and plug connector  602 , which manner and variations thereof were described above with reference to  FIG. 5B . However, instead of having magnetic flux flow into some windows and out of others as with device  500  and plug connector  502 , magnetic flux flows both into and out of each of windows  616  and  624 . 
     Accordingly, plug connector  602  may be used to inductively charge device  600 , and this charging configuration may realize advantages discussed with reference to  FIG. 5B . Implementing unitary magnetically permeable windows may provide additional advantage in some situations, e.g., reducing part count may simplify the manufacturing/assembly process of device  600  and plug connector  602  or may provide a different aesthetic appearance. 
     In some embodiments, one of plug connector  602  and receptacle connector  612  may include a unitary magnetically permeable window while the other connector may include one, two or three magnetically permeable windows, e.g., windows  516   a ,  516   b ,  516   c ,  524   a ,  524   b  and  524   c . Examples of yet additional window variations are illustrated in the following figures. 
     2. Magnetically Permeable Window Frames 
       FIG. 7  illustrates a simplified perspective view of a device  700  and a plug connector  702  corresponding to a receptacle connector  612  of device  600 , according to an embodiment of the present invention. Device  700  and plug connector  702  may be similar to device  600  and plug connector  602 , respectively, except that they each include three magnetically permeable window frames that circumscribe distal tips of magnet elements, instead of two windows covering distal tips of magnetic elements; similar to the differences between device  200  and plug  202  and device  400  and plug  402 , respectively. Accordingly, the description above concerning how device  400  and plug  402  may vary from device  200  and plug  202 , respectively, may also apply here as it pertains to how device  700  and plug connector  702  may differ from device  500  and plug connector  502 , respectively. 
     For example, as shown in  FIG. 7 , device  700  includes a receptacle connector  712  positioned within housing  710  such that a mating surface  714  of receptacle connector  712  is disposed at an exterior of the device housing  710 . Mating surface  714  includes three magnetically permeable window frames  716   a ,  716   b  and  716   c  that frame or circumscribe permanent magnets  744   a ,  744   b  and  744   c  of a first magnetic element (not shown, but see, e.g., magnetic element  532  in  FIG. 5B ). 
     The function of window frames  716   a ,  716   b  and  716   c  may be similar to that of windows  516   a ,  516   b  and  516   c  (shown in  FIGS. 5A and 5B ) to the extent that windows  516   a ,  516   b  and  516   c  provide shielding for magnetic flux from potential interference caused by housing  510 ; however, only incidental magnetic flux may flow through window frames  716   a ,  716   b  and  716   c . Instead, magnetic flux may flow directly from exposed distal tips of permanent magnets  744   a ,  744   b  and  744   c  to corresponding distal tips of permanent magnets  740   a ,  740   b  and  740   c  of a second magnetic element (not shown, but see, e.g., magnetic element  530  in  FIG. 5B ) of plug connector  702 . For simplicity, various internal components, such as the control circuitry, graphics circuitry, bus, memory, storage device and other components are not shown in  FIG. 7 . 
     As further shown in  FIG. 7 , plug connector  702  includes a body  718  having a mating end  720  and a cable  722  attached at an end opposite of mating end  720 . Mating end  720  is sized to interface with mating surface  714  of corresponding receptacle connector  712  during a mating event and includes first, second and third magnetically permeable window frames  724   a ,  724   b  and  724   c  that frame or circumscribe distal tips of permanent magnets  740   a ,  740   b  and  740   c . When plug connector  702  is mated with corresponding receptacle connector  712 , mating end  720  is brought into contact with mating surface  714  such that permanent magnets  740   a ,  740   b  and  740   c  can be aligned with, i.e., centered over, and in contact with permanent magnets  744   a ,  744   b  and  744   c , respectively. 
     Window frames  716   a ,  716   b ,  716   c ,  724   a ,  724   b  and  724   c  may be between about 2 mm and 7 mm tall, about 5 mm and 15 mm wide and about 0.25 mm and 0.5 mm thick and may include an opening for receiving distal ends of permanent magnets  740   a ,  740   b ,  740   c ,  744   a ,  744   b  and  744   c . The frames may be made from a magnetically permeable material that is also electrically insulative, e.g., strong polymers, sapphire or other strong materials that are magnetically permeable and electrically insulative. As further described above with reference to  FIG. 5B , the insulative properties of these materials may insulate magnetic flux from the housing  710 , which may be made from a metallic, conductive material that could cause losses during inductive charging if not insulated. 
     As mentioned above, in contrast with the embodiments described with reference to  FIGS. 5A, 5B and 6 , magnetic flux may flow directly between permanent magnets  740   a  and  744   a ,  740   b  and  744   b , and  740   c  and  744   c  during inductive charging, without passing through a window (e.g., windows  716   a ,  716   b ,  716   c ,  724   a ,  724   b  and  724   c ). Nonetheless, the internal elements and variations thereof discussed with reference to  FIG. 5B  may also be included in device  700  and plug connector  702 . Furthermore, aside from the differences described, device  700  and plug connector  702  may function in a manner similar to device  500  and plug connector  502 , which manner and variations thereof were described above with reference to  FIG. 5B . 
     Accordingly, plug connector  702  may be used to inductively charge device  700 , and this charging configuration may realize advantages discussed with reference to  FIG. 7B . In addition, the gaps between permanent magnets  744   a ,  744   b  and  744   c  and permanent magnets  740   b ,  744   b  and  744   c  may be smaller as compared to other embodiments discussed above because windows (e.g., windows  716   a ,  716   b ,  716   c ,  724   a ,  724   b  and  724   c ) are not disposed between these magnets. As such, the distance or gap between permanent magnets  744   a  and  740   a , permanent magnets  740   b  and  744   b  and permanent magnets  740   c  and  744   c  may be less than about 0.2 mm. Thus, the magnetic flux flow path between device  700  and plug connector  702  may be closed or nearly closed, charging losses may be reduced and inductive charging efficiency may be increased. 
     It will also be appreciated that the device  700  and plug connector  702  described above are illustrative and that various modifications are possible. For instance, the exposed ends of permanent magnets  740   a ,  740   b ,  740   c ,  744   a ,  744   b  and  744   c  may still be otherwise protected from corrosion and scratching, e.g., using a coating, plating and/or an air gap smaller than the window material gap, instead of including magnetically permeable windows that cover the exposed ends of permanent magnets  740   a ,  740   b ,  740   c ,  744   a ,  744   b  and  744   c . As another example, one of plug connector  702  and receptacle connector  712  may include a unitary magnetically permeable window (e.g., windows  616  and  624 , as shown in  FIG. 6 ), while the other connector may include three magnetically permeable windows e.g., windows  716   a ,  716   b  and  716   c  or windows  724   a ,  724   b  and  724   c . Plug connector  702  and receptacle connector  712  may also each include a combination of window frames and windows. 
       FIGS. 2-7  all illustrate embodiments of the present invention that include halves of a magnetic core, e.g., first and second magnetic elements, which are orientated about a single plane. Examples of additional embodiments that include first and second magnetic elements that extend in more than one plane are illustrated in the following figures. 
     C. Multi-Planar Loop Inductive Charging Interface 
       FIG. 8  illustrates a simplified perspective view of the back side of a device  800 , according to an embodiment of the present invention. Device  800  may be similar to other device embodiments discussed above except that the portion of the magnetic core included in device  800  may be disposed in a different location and extend in more than one plane. A corresponding plug connector may be used to inductively charge device  800  (e.g., any of the plug connectors described above that are sized for mating with this particular device and its receptacle connector). 
     As shown in  FIG. 8 , device  800  includes a receptacle connector  812  positioned within housing  810  such that a mating surface  814  of receptacle connector  812  is disposed at an exterior back surface of device housing  810 . Mating surface  814  includes first and second magnetically permeable window  816   a ,  816   b . A first magnetic element  830  (shown in dotted lines) may be included within housing  810  and positioned such that its distal ends are adjacent to windows  816   a ,  816   b . As shown in  FIG. 8 , first magnetic element  830  may include a circular cross-section and may be generally U-shaped except for the curvature provided near its distal tips, leaving the distal tips extending in a direction perpendicular to the plane about which the rest of magnetic element  830  is oriented. 
     Accordingly, device  800  may support inductive charge device. And this charging configuration may provide a number of advantages. For example, first magnetic element  830  may be positioned and shaped so as to accommodate various components within device  800 . Magnetic element  830  may also be otherwise shaped and positioned to meet design requirements for device  800 . This flexibility may allow device  800  to more room for additional and/or different components. At the same time, the design of magnetic element  830  may still guide the magnetic flux flow path between device  800  and a corresponding plug connector in a closed or nearly closed loop, thereby reducing losses and increasing inductive charging efficiency. 
     Again, device  800 , including first magnetic element  830 , as well as a corresponding plug connector, may be similar to devices and plug connectors described above in function and form except for the difference in shape and location of first magnetic element  830 . Thus, the discussion of form, function and additional internal and/or external elements described with reference to  FIGS. 2A-7  may apply to this embodiment as well. Furthermore, embodiments of device  800  and corresponding plug connectors may vary in accordance with variations described with reference to the aforementioned embodiments. 
     It will also be appreciated that the device  800  and corresponding plug connectors described above are illustrative and that various modifications are possible. For instance, receptacle connector  814  may be located on other surfaces of device  800  or on other portions of the back surface. As another example, magnetic element  830  may not be symmetrical, but rather shaped to accommodate various internal components of device  800 . As yet another example, the connector configuration included in device  800  may also be included in plug connectors and receptacle connector  814  may be replaced with other receptacle connector embodiments described herein. 
     Also, while a number of specific embodiments were disclosed with specific features, a person of skill in the art will recognize instances where the features of one embodiment can be combined with the features of another embodiment. For example, some specific embodiments of the invention set forth above were illustrated with receptacle connectors having a recess mating surface. A person of skill in the art will readily appreciate that plug connectors may also include this feature. Further, plug and receptacle connectors may include mating surfaces that are otherwise shaped (e.g., concave, convex, or non-symmetrically shaped) and mating and/or retention features may also be included with the plug and receptacle connectors (e.g., those described with reference to  FIGS. 1A and 1B  and various embodiments thereof). Also, those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the inventions described herein. Such equivalents are intended to be encompassed by the following claims.

Metadata:
Filing Date: 20140929
Publication Date: 20170404
Grant Date: 20170404
Priority Date: 20130930
Inventors: GOLKO ALBERT J.
JOL ERIC S.
BOSSCHER NATHAN P.
MOYER TODD K.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01R13/6205", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J5/005", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F2007/208", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F7/206", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/90", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/0042", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/90", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01R13/6205", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0042", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/70", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01R13/6205", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F2007/208", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F7/206", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/70", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/206", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01R13/6205", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F2007/208", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B5/24", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 52739397