PATENT DOCUMENT

Publication Number: US-10390594-B2
Application Number: US-201816228573-A
Country: US
Kind Code: B2

Title: Inductively chargeable earbud case

Abstract:
A case a portable listening device. The case includes a housing having an interior space to receive the portable listening device; a lid attached to the housing; a rechargeable battery and first and second wireless power receiving elements configured to receive electric charge from a wireless power transmitter during a charging event. The case further includes switching circuitry that is configured to disable one of the first or second wireless power receiving elements during a charging event when the disabled element is receiving power less efficiently than the other element.

Claims:
What is claimed is: 
     
       1. A case for a pair of earbuds, the case comprising:
 a housing having first and second cavities formed within the housing, the first cavity sized and shaped to hold a left earbud in the pair of earbuds and the second cavity sized and shaped to hold a right earbud in the pair of earbuds; 
 a lid attached to the housing and operable between a closed position where the lid is aligned over the first and second cavities and an open position where the first and second cavities are exposed enabling the pair of earbuds to be removed from or placed within the case; 
 a connector having a connector cavity with an opening at the bottom surface of the case and a plurality of contacts positioned within the opening; 
 a rechargeable battery disposed within the housing; 
 one or more wireless power receiving elements disposed within the housing and configured to receive electric charge from a wireless power transmitter during a charging event in which the case is positioned proximate to the wireless power transmitter; and 
 a charging system operatively coupled to receive power from the one or more wireless power receiving elements and transfer the received power to the rechargeable battery. 
 
     
     
       2. The case for a pair of earbuds set forth in  claim 1  wherein the one or more wireless power receiving elements comprises a stranded coil. 
     
     
       3. The case for a pair of earbuds set forth in  claim 1  wherein the one or more wireless power receiving elements comprise a pancake-like coil. 
     
     
       4. The case for a pair of earbuds set forth in  claim 1  wherein one or more wireless power receiving elements include first and second wireless power receiving elements each comprising a solenoid coil. 
     
     
       5. The case for a pair of earbuds set forth in  claim 4  wherein the first and second wireless power receiving elements are electrically connected in parallel. 
     
     
       6. The case for a pair of earbuds set forth in  claim 4  wherein the first and second wireless power receiving elements are independently rectified. 
     
     
       7. The case for a pair of earbuds set forth in  claim 1  wherein the lid is coupled to the housing by a hinge and the case comprises a plurality of magnetic elements disposed within the housing and the lid, the plurality of magnetic elements configured to secure the lid in the closed position and to resist the lid moving from the open to the closed position. 
     
     
       8. The case for a pair of earbuds set forth in  claim 1  wherein the connector comprises a mini-USB connector that can transfer power to the case. 
     
     
       9. A case for a pair of earbuds, the case comprising:
 a housing having first and second opposing major surfaces, first and second opposing sidewalls extending between the first and second major surfaces, a bottom surface extending between the first and second major surfaces and between the first and second sidewalls, and first and second cavities formed within the housing, the first cavity configured to receive a first earbud in the pair of earbuds and the second cavity configured to receive a second earbud in the pair of earbuds; 
 a lid attached to the second major surface of the housing and operable between a closed position where the lid is aligned over the first and second cavities and an open position where the first and second cavities are exposed enabling the pair of earbuds to be removed from or placed within the case; 
 a connector having a connector cavity with an opening at the bottom surface of the case and a plurality of contacts positioned within the opening; 
 a rechargeable battery disposed within the housing; 
 one or more wireless power receiving elements positioned adjacent to the bottom surface, the one or more wireless power receiving elements configured to receive electric charge from a wireless power transmitter during a charging event in which the case is positioned proximate to the wireless power transmitter; and 
 a charging system operatively coupled to receive power from the first and second wireless power receiving elements and transfer the received power to the rechargeable battery. 
 
     
     
       10. The case for a pair of earbuds set forth in  claim 9  wherein the one or more wireless power receiving elements comprise a first wireless power receiving coil and a second wireless power receiving coil. 
     
     
       11. The case for a pair of earbuds set forth in  claim 10  wherein the first and second wireless power receiving coils are connected in series. 
     
     
       12. The case for a pair of earbuds set forth in  claim 11  further comprising switching circuitry coupled to the charging system and configured to, during the charging event, switch the phase of one of the first or second wireless power receiving coils by 180 degrees. 
     
     
       13. The case for a pair of earbuds set forth in  claim 12  wherein the switching circuitry comprises a plurality of rectifiers that independently rectify the first and second wireless power receiving coils. 
     
     
       14. The case for a pair of earbuds set forth in  claim 9  wherein the connector comprises a mini-USB connector that can transfer power to the case. 
     
     
       15. A case for a portable listening device, the case comprising:
 a housing having an interior space to receive the portable listening device; 
 a processor disposed within the housing; 
 a magnet disposed within the housing; 
 a lid attached to the housing by a hinge and operable between a closed position where the lid is aligned over the interior space and an open position where interior space is exposed enabling the portable listening device to be removed from the interior space; 
 a rechargeable battery disposed within the housing; 
 a wireless power receiving module comprising: (i) a wireless power receiving element positioned within the housing, the first wireless power receiving element configured to receive electric charge from a wireless power transmitter during a charging event in which the case is positioned proximate to the wireless power transmitter, and (ii) a ferrite plate disposed between the wireless power receiving element and the processor; and 
 a charging system operatively coupled to receive power from the wireless power receiving element and transfer the received power to the rechargeable battery. 
 
     
     
       16. The case for a pair of earbuds set forth in  claim 15  wherein the wireless power receiving module comprises a stranded coil. 
     
     
       17. The case for a pair of earbuds set forth in  claim 15  wherein the wireless power receiving module comprises a coil formed on a flex circuit. 
     
     
       18. The case for a pair of earbuds set forth in  claim 15  wherein the one or more wireless power receiving elements comprise a pancake-like coil. 
     
     
       19. The case for a pair of earbuds set forth in  claim 15  wherein the case comprises first and second magnets positioned on opposite sides of the housing adjacent to the hinge and the ferrite plate covers the wireless power receiving element except at a first location adjacent to the first magnet and a second location adjacent to the second magnet. 
     
     
       20. The case for a pair of earbuds set forth in  claim 19  wherein:
 the case comprises third and fourth magnets positioned on opposite sides of the lid adjacent to the hinge and adjacent to the first and second magnets, respectively, when the lid is in the closed position; 
 the first magnet repels the third magnet and the second magnet repels the fourth magnet when the lid is in the closed position; and 
 the first magnet attracts the third magnet and the second magnet attracts the fourth magnet when the lid is in the closed position.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 15/697,315, entitled “INDUCTIVELY CHARGEABLE EARBUD CASE” filed Sep. 6, 2017, which claims benefit to U.S. Provisional Patent Application No. 62/384,105, entitled “DUAL SOLENOID INDUCTIVE CHARGING FOR EARBUD CASE” which was filed Sep. 6, 2016, each of which is hereby incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     Electronic devices (e.g., mobile phones, media players, electronic watches, and the like) operate when there is charge stored in their batteries. Batteries can be charged by coupling the electronic device to a power source through a physical connection, such as through a charging cord. Using charging cords to charge batteries in electronic devices, however, requires the electronic device to be physically tethered to a power outlet. Additionally, using charging cords requires the mobile device to have a receptacle configured to mate with the charging cord. The receptacle is typically a cavity in the electronic device that provides avenues within which dust and moisture can intrude and damage the device. Furthermore, a user of the electronic device has to physically connect the charging cable to the receptacle in order to charge the battery. 
     To avoid such shortcomings, wireless charging devices have been developed to charge electronic devices without the need for a charging cord. Electronic devices may charge by merely resting on a charging surface of the charging device. Magnetic fields generated by transmitters disposed below the charging surface may induce corresponding currents in receivers that have a corresponding inductive coil. The induced currents may be used by the electronic device to charge its internal battery. 
     Some conventional wireless charging applications rely upon precise alignment of transmission and receiving coils to achieve efficient wireless charging. In such devices, the efficiency of inductive charging typically drops rapidly with any misalignment of the transmission and receiving coils. This may limit the number of ways in which a charger for an electronic device can be designed and/or provide a less than ideal user experience for inductive charging. 
     SUMMARY 
     Embodiments of the disclosure pertain to portable electronic devices that can be wirelessly charged on a charging surface, such as an inductive charging mat or pad that provides power at different locations along the charging surface. An electronic device according to the disclosure can generally receive charge when positioned anywhere within the charging surface. While embodiments of the disclosure can include many different types of portable electronic devices, some embodiments pertain to a case for a portable listening device, such as a pair of headphones or a pair of wireless earbuds. The case can include one or more cavities to hold the listening device and charging circuitry to provide power to a rechargeable battery within the listening device (or within each of the pair of earbuds). 
     According to some embodiments an electronic device can include first and second wireless power receiving coils (e.g., solenoid coils) that can wirelessly receive power from one or more wireless power transmit coils within the charging mat. The first and second coils can each receive wireless power at varying degrees of efficiency from the transmit coils depending on the location of each of the first and second wireless power receiving coils vis-à-vis the wireless power transmitting coils. Generally, one of the first and second receiving coils will receive power at a higher efficiency than the other. The electronic device can include switching circuitry that can identify and disable the wireless receiving coil that receives power at the lower efficiency in order to receive a higher overall charging efficiency for the electronic device than if both wireless receiving coils receive power. 
     In some embodiments a case for a portable listening device is provided. The case can include a housing having an interior space to receive the portable listening device; a lid attached to the housing and operable between a closed position where the lid is aligned over the interior space and an open position where interior space is exposed enabling the portable listening device to be removed from the interior space; a first wireless power receiving element positioned within the housing at a first location, the first wireless power receiving element configured to receive electric charge from a wireless power transmitter during a charging event in which the case is positioned proximate to the wireless power transmitter; a second wireless power receiving element positioned within the housing at a second location, different than the first location, the second wireless power receiving element configured to receive electric charge from the wireless power transmitter during the charging event; a charging system operatively coupled receive power from the first and second wireless power receiving elements and transfer the received power to a rechargeable battery; and switching circuitry coupled to the charging system and configured to, during the charging event, disable one of the first or second wireless power receiving elements if the disabled element is receiving power less efficiently than the other element. 
     In various examples a portable listening device case can also include one or more of the following: the switching circuitry can include passive analog circuitry that automatically deactivates the wireless power receiving element receiving power at a lower efficiency, each of the first and second wireless power receiving elements can be a solenoid coil, and/or the case can be a case for a pair of earbuds and the housing includes first and second cavities to receive the pair of earbuds. 
     In some embodiments a case for a pair of earbud is provided. The case can include: a housing having first and second opposing major surfaces, first and second opposing sidewalls extending between the first and second major surfaces, a bottom surface extending between the first and second major surfaces and between the first and second sidewalls, and first and second cavities formed within the housing, the first cavity configured to receive a first earbud in the pair of earbuds and the second cavity configured to receive a second earbud in the pair of earbuds; a lid attached to the second major surface of the housing and operable between a closed position where the lid is aligned over the first and second cavities and an open position where the first and second cavities are exposed enabling the pair of earbuds to be removed from or placed within the case; a connector having a connector cavity with an opening at the bottom surface of the case and a plurality of contacts positioned within the open; a first wireless power receiving coil positioned within the housing between the opening and the first sidewall, the first wireless power receiving element configured to receive electric charge from a wireless power transmitter during a charging event in which the case is positioned proximate to the wireless power transmitter; a second wireless power receiving coil positioned within the housing between the opening and the second sidewall, the second wireless power receiving element configured to receive electric charge from the wireless power transmitter during the charging event; and a charging system operatively coupled receive power from the first and second wireless power receiving elements and transfer the received power to a rechargeable battery. 
     In other embodiments a case for a portable listening device can include: a housing having an interior space to receive the portable listening device, the housing having first and second major opposing surfaces that define an exterior surface of the case; a processor disposed within the housing; a magnet disposed within the housing; a lid attached to the housing by a hinge and operable between a closed position where the lid is aligned over the interior space and an open position where interior space is exposed enabling the portable listening device to be removed from the interior space; a wireless power receiving module comprising: (i) a wireless power receiving element positioned within the housing adjacent to the first major surface, the first wireless power receiving element configured to receive electric charge from a wireless power transmitter during a charging event in which the case is positioned proximate to the wireless power transmitter, and (ii) a ferrite plate disposed between the wireless power receiving element and the processor, the ferrite plate having a surface area that covers the wireless power receiving element except at a location adjacent to the magnet; and a charging system operatively coupled receive power from the wireless power receiving element and transfer the received power to a rechargeable battery. 
     In various examples the case can also include one or more of the following: the wireless power receiving module comprises a stranded coil, the wireless power receiving module comprises a coil formed on a flex circuit, first and second magnets positioned on opposite sides of the housing adjacent to the hinge and the ferrite plate covers the wireless power receiving element except at a first location adjacent to the first magnet and a second location adjacent to the second magnet. Also in addition to first and second magnets as described, in some embodiments the case can further include third and fourth magnets positioned on opposite sides of the lid adjacent to the hinge and adjacent to the first and second magnets, respectively, when the lid is in the closed position. The magnets can be arranged such that the first magnet repels the third magnet and the second magnet repels the fourth magnet when the lid is in the closed position, and the first magnet attracts the third magnet and the second magnet attracts the fourth magnet when the lid is in the closed position. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a simplified perspective view of an earbud case according to some embodiments of the disclosure; 
         FIG. 2  illustrates a simplified perspective view of an earbud case according to some embodiments of the disclosure; 
         FIG. 3  illustrates a simplified perspective view of an earbud case according to some embodiments of the disclosure; 
         FIG. 4  illustrates an example of a solenoid coil that can be incorporated into the earbud cases shown in  FIGS. 1, 2 and 3  according to some embodiments; 
         FIG. 5  illustrates an example of a charging pad that can be used to charge an earbud case according to embodiments of the disclosure; 
         FIG. 6  illustrates two different positional placements of an earbud case according to the disclosure on the charging pad shown in  FIG. 5 ; 
         FIG. 7  is a simplified block diagram depicting various components of an earbud case according to some embodiments of the disclosure; 
         FIG. 8A  is a simplified side plan view of case  100  shown in  FIG. 1  according to some embodiments of the disclosure; 
         FIG. 8B  is a simplified side plan view of case  200  shown in  FIG. 2  according to some embodiments of the disclosure; 
         FIG. 8C  illustrates different positional placements of earbud cases according to the present disclosure on charging pad  500  shown in  FIG. 5 ; 
         FIG. 9A  depicts a simplified perspective view of an earbud case according to additional embodiments of the disclosure; 
         FIG. 9B  is a simplified side plan view of case  900  shown in  FIG. 9A  according to some embodiments of the disclosure; 
         FIG. 9C  is a simplified illustration of a wireless power receiving element according to some embodiments of the disclosure; 
         FIG. 10  is a flowchart depicting steps associated with forming a wireless power receiving coil according to some embodiments of the disclosure; 
         FIG. 11  depicts the coil formed by the method of  FIG. 10  at various stages of the formation process; 
         FIG. 12  is top plan view of a coil module according to some embodiments of the disclosure; 
         FIG. 13  depicts a simplified rear plan view of an earbud case that includes the coil module shown in  FIG. 12 ; 
         FIG. 14  is top plan view of another coil module according to some embodiments of the disclosure; and 
         FIG. 15  depicts a simplified rear plan view of an earbud case that includes the coil module shown in  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the disclosure pertain to portable electronic devices that can be wirelessly charged in multiple positions on a charging surface, such as an inductive charging mat or pad that provides power at different locations along the charging surface. In some embodiments the electronic device can include first and second wireless power receiving coils that can wirelessly receive power from one or more wireless power transmit coils within the charging mat. Depending on the position of the portable electronic device on the charging mat, one of the first or second coils can will likely receive power at a higher efficiency than the other. As stated above, in some embodiments, the portable electronic device being charged includes circuitry that recognizes which of the first and second wireless power receiving coils is receiving power at a lower efficiency rate and disables that receiving coil. Disabling the wireless power receiving coil receiving power at the lower efficiency can result in a higher overall charging efficiency for the portable electronic device than if both wireless receiving coils were allowed to receive power. 
     While embodiments of the disclosure can include many different types of electronic devices, some embodiments pertain to portable electronic devices that can be wirelessly charged including smart phones, tablet computers and other devices. Still other embodiments pertain to a case for a portable listening device, such as a pair of headphones or a pair of wireless earbuds. The case can include one or more cavities to hold the listening device and charging circuitry to provide power to a rechargeable battery within the listening device (or within each of the pair of earbuds). The case can also include first and second wireless power receiving elements and circuitry that disables either the first or second receiving element depending on which element is receiving power at the lower efficiency level. In some particular embodiments, each of the wireless power receiving elements are coils. 
     As used herein, the term “portable listening device” includes any portable device designed to play sound that can be heard by a user. Headphones are one type of portable listening device, portable speakers are another. The term “headphones” represents a pair of small, portable listening devices that are designed to be worn on or around a user&#39;s head. They convert an electrical signal to a corresponding sound that can be heard by the user. Headphones include traditional headphones that are worn over a user&#39;s head and include left and right listening devices connected to each other by a headband, headsets (a combination of a headphone and a microphone); and earbuds (very small headphones that are designed to be fitted directly in a user&#39;s ear). Traditional headphones include both over-ear headphones (sometimes referred to as either circumaural or full-size headphones) that have earpads that fully encompass a user&#39;s ears, and on-ear headphones (sometimes referred to as supra-aural headphones) that have earpads that press against a user&#39;s ear instead of surrounding the ear. As used herein, the term “earbuds”, which can also be referred to as earphones or ear-fitting headphones, includes both small headphones that fit within a user&#39;s outer ear facing the ear canal without being inserted into the ear canal, and in-ear headphones, sometimes referred to as canalphones, that are inserted in the ear canal itself. 
       FIG. 1  illustrates a simplified perspective view of an earbud case  100  according to some embodiments of the disclosure. Earbud case  100  includes a housing  105  and a lid  110  that can be pivotably coupled to housing  105  by a hinge  125 . Housing  105  defines an interior space in which a pair of earbuds (not shown) can be stored. In some embodiments an insert can be fit within the interior space to define one or more cavities that are sized and shaped to accept the earbuds. 
     Lid  110  can be moved between a closed position in which the lid covers the interior space and an open position (illustrated in  FIG. 1 ) in which an opening  115  of the housing is exposed to allow a user to place the earbuds within or remove the earbuds from the interior space. While not shown in  FIG. 1 , earbud case can include a battery, charging circuitry to charge the battery and/or earbuds stored within the case, and other circuitry and components. In some embodiments, case  100  can also include a receptacle connector  120  that has an opening at an exterior surface of case  100  (e.g., the bottom surface as shown in  FIG. 1 ). A suitable plug connector can be inserted in the opening to mate with the receptacle connector and transfer power to case  100  (e.g., from a charging cable) and/or to transfer data between case  100  and another device. Receptacle connector  120  can be, for example, a mini-USB connector, a Lightning connector developed by Apple Inc., the assignee of the present application, or any other appropriate connector. 
     Earbud case  100  can also include first and second wireless power receiving elements  122  and  124  that can wirelessly receive power from a wireless transmitter (e.g., a wireless transmitting coil) and provide the power to the charging circuitry. In the embodiment shown in  FIG. 1 , wireless power receiving elements  122 ,  124  are each receiver coils disposed within the interior space defined by housing  105  and can be positioned at opposite corners of the space near the bottom of case  100 . Because of the physical separation between coils  122 ,  124 , the coils may be aligned differently from each other with respect to the wireless power transmitters of a charging pad when earbud case  100  is placed on the charging pad. Thus, each wireless power receiving element will likely receive wireless power from the charging pad at different efficiency rates as described below. 
     While each of the wireless receiving elements are shown in  FIG. 1  as being positioned in opposing corners of the interior cavity formed by housing  105 , embodiments of the disclosure are not limited to any particular placement of the receiving elements. In other embodiments, the wireless receiving elements can be located at different positions within the housing. For example, as shown in  FIG. 2  an earbud case  200  includes coils  222 ,  224  disposed along opposing sides of the interior space defined by housing  105  such that the coils extend from a bottom surface of the space towards lid  110 . In another embodiment shown in  FIG. 3 , an earbud case  300  includes coils  322 ,  324  that extend along the bottom of the interior space along the width of the case in the space between connector  120  and the front and back of housing  105 , respectively, along with coils  326 ,  328  in lid  110 . Additionally, while the various embodiments depicted in  FIGS. 1-3  each include a specific number of coils, embodiments of the disclosure are not limited to any particular number of coils and some embodiments may have a single coil while other embodiments may have more than two or more than four coils. 
     Referring to each of  FIGS. 1-3 , in some embodiments each of first and second wireless power receiving elements  122 ,  124  or  222 ,  224  or  322 ,  324  are three-dimensional solenoid coils.  FIG. 4  is a simplified diagram of an example of a solenoid coil  400  that can be incorporated into any of earbud cases  100 ,  200  or  300  according to some embodiments. Solenoid coil  400  includes a coil of wire  405  wrapped around a conductive core  410 . 
       FIG. 5  illustrates an example of a charging pad  500  that can be used to charge an earbud case according to embodiments of the disclosure. Charging pad  500  includes multiple wireless power transmitting coils  505  that are configured to wireless transmit power within a charging area  510  that closely corresponds to the size of charging pad  500 . Each of the wireless power transmitting coils  505  is placed at a particular position with respect to other coils in a coil pattern to provide highly efficient charging of an accessory device, such as earbud case  100 ,  200  or  300 , at any location within charging area  510 . In this manner, charging pad  500  does not require precise alignment of any or more of the wireless power transmitting coils to a wireless power receiver of an accessory or other electronic device to be charged by pad  500 . The actual efficiency of a given charging event, however, will depend on the alignment of the wireless power receiver within the accessory or other electronic device to individual ones of the wireless power transmitting coils  505  within pad  500 . 
       FIG. 6  illustrates two different electronic devices  100   a  and  100   b  placed on charging pad  500  at different locations. Each of electronic devices  100   a ,  100   b  can be, for example, earbud charging case  100  discussed above. Electronic device  100   a  includes first and second wireless power receiving elements  122   a ,  124   a  while electronic device  100   b  includes first and second wireless power receiving elements  122   b ,  124   b . Each of wireless power receiving elements  122   a ,  124   a  and  122   b ,  124   b  can be, for example, three-dimensional solenoid coils similar to coil  400  shown in  FIG. 4 . 
     As shown in  FIG. 6 , first and second wireless power receiving elements  122   a ,  124   a  of device  100   a  are each positioned over different portions of the wireless transmitting coil pattern. In rare instances, the placement of each receiving element  122   a ,  124   a  will be optimal with respect to the transmitting coils in charging pad  500  in which instance both the receiving elements will wirelessly receive power from the charging pad at equal efficiency rates. In all other instances, however, one of the wireless power receiving elements will wirelessly receive power from the charging pad at a higher efficiency rate than the other. The lower efficiency wireless receiving element can leak power which can result in a charging loss from that element without any overall charging benefit to the device being charged. 
     Embodiments of the disclosure can include switching circuitry that recognizes which of the two coils is operating at lower efficiency and automatically chooses to connect the higher efficiency coil to the charging circuitry disabling the lower efficiency coil. In some embodiments, the switching circuitry does not including any digital logic circuits and instead all the switching is handled by analog circuitry. The analog circuitry can be passive circuitry that does not have to actively choose one receiving element over another; instead, the switching can happen automatically. In some particular embodiments, the analogy switching circuitry can be a diode bridge coupled between the first and second power receiving coils and the charging circuitry that transfers power to a rechargeable battery. 
     As an example, based on its placement on charging pad  500  shown in  FIG. 6 , accessory  100   a  might be positioned such that wireless power receiving element  122   a  receives power more efficiently than element  124   a . Thus, the switching circuitry within accessory  100   a  automatically disables wireless power receiving element  124   a  so that only receiving element  122   a  receives wireless power from the charging pad. Accessory  110   b , on the other hand, might be positioned such that wireless power receiving element  124   b  receives power more efficiently than element  122   b . Thus, the switching circuitry within accessory  100   b  can automatically disable wireless power receiving element  122   b  so that only receiving element  124   b  receives wireless power from the charging pad. 
       FIG. 7  is a simplified block diagram depicting various components of a wireless power charging system  700  according to some embodiments of the disclosure. Charging system  700  includes a wireless charging pad  710 , an earbud case  720  and a pair of earbuds  740   a ,  740   b . Wireless charging pad can be representative of wireless charging pad  500  discussed above with respect to  FIG. 5 , and earbud case  720  can be representative of any of earbud cases  100 ,  200  or  300  discussed above with respect to  FIGS. 1-3 . 
     Wireless charging pad  710  can include multiple wireless power transmitters  712  (e.g., multiple power transmitting coils  505 ) disposed beneath the surface of the charging area. The multiple wireless power transmitters enable charging pad  710  to simultaneously wireless charge more electronic devices and enable the devices being charged to be randomly placed within a charging area of the charging pad  710  defined by the placement of the wireless power transmitters. 
     Earbud case  720  includes first and second wireless power receiving elements  722 ,  724  (e.g., coils  122 ,  124 ), switching circuitry  726 , a battery  728 , charging circuitry  730 , and an earbud interface  732 . Battery  728  can be a rechargeable battery that provides power for circuitry associated with earbud case  720 . Wireless power receiving elements  722 ,  724  can wirelessly receive power from the wireless power transmitters  712  within charging pad  710 . The received power can be provided to charging circuitry  730  to charge rechargeable battery  728 . Charging circuitry can take the voltage received from receiving elements  722 ,  724  and step the voltage down or up as appropriate to a voltage level that is best suited for charging battery  728 . 
     When the earbuds are properly positioned and stored within case  720 , battery  728  can also be used to charge one or both of earbud rechargeable batteries  744   a ,  744   b  within the respective earbuds  740   a ,  740   b  through a connection between earbud interface  732  within the earbud case and the case interfaces  742   a ,  742   b  within each earbud. In this manner, batter  728  enables the earbuds to be charged even though case  720  is not electrically coupled to power source  710  or to another power source. Thus, case  720  can be used to charge pair of earbuds  740   a ,  740   b  while the case is, for example, in a user&#39;s pocket as long as case battery  728  has sufficient charge. Each earbud  740   a ,  740   b  also includes a speaker and other components  746   a ,  746   b  that enable the earbuds to generate sound. 
     Additionally, earbud case  720  can recharge batteries  744   a ,  744   b  within each of earbuds  740   a ,  740   b  when the earbuds are properly stored in case  720  from power stored within battery  728  even when the case is not receiving power from charging pad  710 . 
     According to some embodiments, switching circuitry  726  is coupled between the wireless power receiving elements  722 ,  724  and charging circuitry  730 . In some embodiments wireless power receiving elements  722 ,  724  can be connected in parallel with each other while in other embodiments the wireless power receiving elements can be connected in series. When connected in parallel and the power receiving elements are in the same phase, switching circuitry  726  can selectively deactivate one of the power receiving elements to improve charging efficiency. For example, in instances where the placement of earbud case  720  on charging pad  710  results in each receiving element  722 ,  724  being at an optimal position with respect to the transmitting coils in charging pad  710 , power from both wireless power receivers  722 ,  724  can pass through switching circuitry  726  to charging circuitry  730 . In other instances, where one of the wireless power receiving elements is receiving power at a higher efficiency rate than the other, switching circuitry  726  can disable the lower efficiency element by disconnecting it from the charging circuitry. In some embodiments, switching circuitry  726  can be passive analog circuitry (e.g., a diode bridge) that enables the switching to happen automatically. Thus, if earbud case  720  is moved to a different position on charging pad  710  in the middle of a charging event such that the deactivated wireless power receiver suddenly becomes the higher efficiency receiver, switching circuitry  726  automatically switches the newly higher efficiency receiver to charging circuitry  730  and deactivates the other wireless power receiver that was previously providing power to the charging circuitry when the earbud case was in the former position. In other embodiments, switching circuitry  726  can be active circuitry. 
     In some embodiments, wireless power receiving elements  722 ,  724  can be connected in series such that current is driven through both elements in the same direction. Rather than disconnect one of the power receiving elements in such embodiments, switching circuitry  726  can invert the phase of one receiving elements  722 ,  724 . Thus, for example, instead of switching the element at the lower efficiency level off during charging, switching circuitry  726  can invert the phase of one of the elements by 180 degrees driving current up one of coils  722 ,  724  and driving current down the other coil enabling both coils to be operable during a charging event to further improve charging efficiency. 
     In some embodiments, wireless charging mat  710  can be an “intelligent mat” that can determine the phase of each individual coil of wireless power transmitters  712  in response to communication between the device. Charging mat  710  can detect, based on charging efficiency, what phase is optimal to charge a given device and set the phase of individual coils appropriately. When two devices share the same coil, however, the ideal phase for the first device may be different than the ideal phase for the second device. 
     In some embodiments of the present disclosure, switching circuitry  726  can independently rectify each receiving element  722 ,  724  enabling the receiving elements to go to DC separate from each other. Such embodiments can be particularly beneficial when multiple devices are simultaneously being charged by an intelligent charging mat. For example, referring back to  FIG. 5 , if a second device (e.g., an inductively chargeable smart watch) is placed on mat  500  at a position proximate to a position that earbud case  100   a  is positioned such that the two devices may try to share charge from the same coil within mat  500 . The charging mat cannot necessarily chose a phase for that coil that would be ideally suited to charge both devices. Independently rectifying the receiving elements  722 ,  724  in both devices in such an instance allows the earbud case to select the relative phases of each wireless receiving element thus enabling the devices to be optimally charged. Independent rectification is also an advantage is one of the receiving elements is hanging off the edge of charging mat. 
     Referring back to  FIG. 1 , the wireless power receiving coils  122 ,  124  are positioned near the bottom of case  100 . Thus, the center of each power receiving coil (represented by dashed line  805 ) is spaced apart a distance D 1  from the center of the case (represented by dashed line  810 ) as shown in  FIG. 8A , which is a simplified side view of case  100 . Because of the placement of the power receiving coils relative to the center of the case, if case  100  is positioned on charging mat  500  near an outer edge of the mat, the charging efficiency may depend on the orientation at which the case is positioned on the mat. For example, as shown in  FIG. 8C , if an earbud case  100   a  is positioned near an outer edge of charging mat  500  such that the wireless power receiving coils are positioned near the outer edge of the mat, the coils may not be directly over one or more of the wireless power transmitting coils  505  resulting in a decreased charging efficiency. If, on the other hand, an earbud case  100   b  is positioned near the same outer edge of mat  500  but in a reversed orientation, the power receiving coils are more likely to be positioned directly over one or more of the wireless power transmitting coils  505  enabling an efficient charge. The user may not be aware that the orientation of the case relative to an edge of the mat has an impact on charging efficiency in this manner. Similar charging efficiency issues may exist with the placement of the wireless power receiving coils  322 ,  326  or  324 ,  328  in case  300 . 
     Some embodiments of the disclosure address this issue by ensuring that the center of the wireless power receiving coils is at or very close to the center of the case. For example, as shown in  FIG. 8B , which is a simplified side view of case  200 , the center of each power receiving coil  222 ,  224  (represented by dashed line  815 ) is spaced apart a distance D 2  from the center of the case where D 2  is considerably smaller than D 1 . As shown in  FIG. 8C , earbud cases  200   a  and  200   b  can each be positioned near an outer edge of charging mat  500  in opposite orientations while still ensuring that the wireless power receiving coils of each case are generally positioned over one or more of the wireless power transmitting coils  505  resulting in relatively efficient wireless charging of earbud cases  200   a  and  200   b  by mat  500 . 
     Additionally, instead of using solenoid coils as the wireless power receiving elements, some embodiments of the disclosure can include one or more generally flat coils formed along a back and/or front wall of an earbud case or other electronic device. For example,  FIG. 9A  is a simplified perspective view of an earbud case  900  according to some embodiments of the disclosure. Case  900  includes many of the same features as cases  100 ,  200  and  300  and thus uses many of the same reference numbers. Instead of having a pair of solenoid coils as wireless power receiving elements  122 ,  124 , however, case  900  has a single pancake-like coil  902  formed along a back wall of case  900 —the same wall in which a hinge is attached to couple body  105  to lid  110 . Similar to cases  200   a ,  200   b , case  900  can be positioned with near an outer edge of a charging mat  500  with its back surface against the mat in any orientation and still wirelessly receive an efficient charge. 
     In other embodiments, an earbud case according to the present disclosure can include a first coil on a back surface of the case as shown in  FIG. 9A  and a second coil, similar to the first coil, formed along a front wall of the case. Such an embodiment enables the case to be charged with either the front or the back surface placed down on a charging mat. Still other embodiments can include a coil that encircles the case along an inner periphery of body  105 , which also enables charging from either the front or back surface, such as coil  922  shown in  FIG. 9C . 
     Coil  902  can be a stranded coil, a coil formed on a flex circuit or another type of coil and can be completely flat or can formed into a curved shape to match the curvature of case  900  (e.g., coil  902  can curve inward near each of the sides of the case  900 ). Since the coil is formed closer to the center of case  900 , as shown in  FIG. 9B , a center  915  of coil  902  is closely spaced by distance D 3  to the center  810  of case  900 . Thus, the charging efficiency of cases  200  and  900  generally does not depend much on the orientation of cases when the cases are placed near an edge of the charging mat. 
     In some embodiments coil  902  is part of a coil module that can be formed according to the method shown in  FIGS. 10 and 11  and inserted into case  900 . To illustrate such, reference is made to both  FIGS. 10 and 11  where  FIG. 10  is a flowchart depicting steps associated with forming coil  902  and  FIG. 11  depicts the coil at various the stages of formation set forth in  FIG. 10 . As shown in  FIG. 10 , an initial step in the formation of the coil module is forming a coil winding  1102  (step  1010 ) from a stranded wire although in other embodiments the coil can be formed with conductive traces formed on a flex. In embodiments where the size of the coil is maximized and the earbud case includes one or more curved surfaces, coil winding  1102  can be heat formed to match the curvature of the earbud case to form a curved coil winding (step  1020 ). In the embodiment depicted in  FIG. 11 , the coil winding is bent along arrows  1106  such that the coil is curved at its two opposing ends  1104  to match the curvature of the sides of an earbud case  900 . 
     Next, the curved coil winding can be attached to a ferrite plate  1108  with an adhesive or other appropriate technique (step  1030 ). In the final assembly when the receiver coil is attached to the earbud case, ferrite plate  1108  is positioned between coil  1102  and the control circuitry (e.g., a microcontroller or similar processor and/or one or more other integrated circuits such as a wireless communication controller, an ASIC, etc.) of the earbud case. In this manner ferrite plate  1108  both shields the sensitive internal components in the earbud case from magnetic flux generated by the wireless charging device that provides wireless power to receiver coil  1102  while allowing the receiver coil to be exposed to the magnetic flux to before being blocked by the ferrite plate. In some embodiments ferrite plate  1108  includes two separate ferrite layers. For example, in one particular embodiment ferrite plate  1108  includes a first ferrite layer sandwiched between two thin polyethylene terephthalate (PET) layers and a second ferrite layer formed over a thin PET layer and attached to the first ferrite layer stack by a thin pressure sensitive adhesive (PSA) layer. In some embodiments ferrite plate  1108  is less than 500 microns thick. In one particular example, the first ferrite layer is 80 microns thick, each PET layer and the PSA layer is 10 microns thick and the second ferrite layer is 120 microns thick such that ferrite plate  1108  has a total thickness of about 240 microns. 
     The coil/ferrite subassembly can then be attached to an insert housing  1110  (step  1040 ) using a UV glue or other type of adhesive. In some embodiments case  900  includes a user input button centered on the back of housing  105  below the hinge. Insert housing  1110  can house components associated with the input button and is thus sometimes referred to herein as button housing  1110 . Prior to attaching button housing  1110  to housing  105 , the leads of coil  1104  can be soldered to contacts on the housing (step  1050 , not shown in  FIG. 11 ) so that electrical components within case  105  (e.g., charging circuit  730 , battery  728 ) can be electrically coupled to the coil. Then, button housing  1110  can be inserted into and attached to earbud housing  105  for the earbud case  900  (step  1060 ). 
     Reference is now made to  FIG. 12 , which is top plan view of a coil module  1200  having a coil  1202  attached to a ferrite plate  1204 . As shown in  FIG. 12 , ferrite plate  1204  generally covers the entirety of coil  1202  to provide protect components within the earbud case from magnetic flux as described above.  FIG. 13  illustrates a simplified rear plan view of an earbud case  1300  that includes coil module  1200  within housing  105  at a location adjacent to a back surface of the housing. 
     In some embodiments an electronic device that includes a receiver coil according to the present disclosure may also include one or more magnets that can assist in the operation of the device. For example, in some embodiments an earbud case according to the present disclosure can include a lid  110  having an over-center configuration where the lid is in a first stable position when in a closed position and is in a second stable position when in a fully open position, but is generally in an unstable position in-between the closed position and the open position. Such a configuration can be referred to as a bi-stable configuration where, when the lid is between the open and closed positions, it tends to be attracted to either the closed or the open position. In some embodiments the bi-stable operation of the lid can be enabled by magnets in the lid and in the case. In the bi-stable configuration the magnets combine to secure the lid in the closed position and to resist the lid moving from the open to the closed position. 
       FIG. 15  illustrates a simplified rear plan view of an earbud case  1500  that includes a lid  110  having such a bi-stable operation. As shown in  FIG. 15 , earbud case  1500  includes a first pair of magnets  1502 ,  1504  in lid  110  and a second pair of magnets  1506 ,  1508  attached to housing  105  at a location adjacent to a back surface of the housing. Magnets  1506 ,  1508  are spaced apart from magnets  1502 ,  1504  and be aligned to generate repulsive forces that tend to move lid  110  to the open position when the lid is in the closed position, and when the lid is in the open position, generate attraction forces that tend to keep the lid in the open position. Additional magnets (not shown) positioned at the front surface of the lid and housing of earbud case  1500  generate attractive forces that over power the repulsive forces of magnets  1502 ,  1504  and  1506 ,  1508  when the lid is closed or close to a closed position. 
     The inventors discovered that the presence of magnets  1506 ,  1508  can have an adverse impact on the flux generated within earbud case  1500  during a charging event. Specifically, the magnets that repel each other can push flux away from the magnets creating a leaky flux situation. The ferrite plate is relatively permeable and pulls the flux towards it saturating the ferrite. To address this issue, some embodiments of the disclosure create a cutout region  1406  (see  FIG. 14 ) at each of the two corners of a ferrite plate  1404  (that is otherwise similar to ferrite plate  1204 ) that are located near magnets  1506 ,  1508 . The cutout regions  1406  are located directly behind a portion of coil  1202  creating an air barrier (low permeability) between the repulsion magnets  1506 ,  1508  and portions of coil  1202  where the ferrite plate would otherwise have been. The inventors have found that removing cutout regions  1406  of ferrite plate  1404  makes the ferrite plate more effective than a plate that fully covers coil  1202 . The inventors have found that, counter intuitively, such a configuration improves flux uniformity and hence improves charging. 
     While the various embodiments and examples described above were primarily focused on an earbud case for storing earbuds, embodiments of the disclosure are not limited to such and the techniques of the disclosure described above are equally applicable to other portable electronic devices including wearable devices, smart phones, and tablet computers among others. Also, other embodiments of the disclosure are applicable to cases for other types of headphones. For example, in one embodiment, case  100  described in  FIG. 1  can be a case for a pair of headphones instead of a pair of earbuds. In an earbud embodiment, two separate cavities can formed within housing  105  where one cavity is sized and shaped to hold a left earbud and the other cavity is sized and shaped to hold a right earbud. Similarly, in other embodiments, case  100  can be sized and shaped to hold a portable speaker or other type of listening device.

Metadata:
Filing Date: 20181220
Publication Date: 20190827
Grant Date: 20190827
Priority Date: 20160906
Inventors: BRZEZINSKI, MAKIKO K.
WALTON, CHRISTOPHER J.
GRAHAM, Christopher S.
WAGMAN, Daniel C.
JOL, ERIC S.
Assignee: APPLE INC
CPC Classifications: [{"code": "A45C2013/025", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/0044", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1016", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/0044", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1016", "inventive": false, "first": false, "tree": "[]"}, {"code": "A45C13/02", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/0013", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C11/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C11/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0013", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1025", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C13/02", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/1025", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C2013/025", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1025", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C11/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R1/1016", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/0013", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0044", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C2013/025", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "A45C13/02", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/402", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/402", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 61281728