PATENT DOCUMENT

Publication Number: US-10727695-B2
Application Number: US-201816127898-A
Country: US
Kind Code: B2

Title: Inductive charging module

Abstract:
This disclosure describes a portable electronic device that includes an inductive charging receiver for receiving power wireless from a charging device. The portable electronic device includes a device housing including a wall having a channel formed in an interior-facing surface of the wall. The portable electronic device also includes an inductive coil assembly for receiving power wirelessly that is coupled to the interior facing surface. The inductive coil assembly is a flat coil that includes concentric loops of electrically conductive material that define a central opening. A first electrical lead extends away from a peripheral portion of the flat coil and a second electrical lead extends from the central opening, into the channel formed in the back wall and beneath one side of the concentric loops.

Claims:
What is claimed is: 
     
       1. A portable electronic device, comprising:
 a device housing comprising a wall having a channel formed in an interior-facing surface of the wall; 
 an electronic component disposed within the device housing; and 
 an inductive coil assembly disposed between the interior-facing surface and the electronic component, the inductive coil assembly comprising: concentric loops of electrically conductive material that define a central opening, a first electrical lead extending away from a peripheral portion of the inductive coil assembly, and a second electrical lead; 
 a ferrite sheet disposed between the electronic component and the inductive coil assembly; 
 wherein a length of the channel in the interior-facing surface of the wall extends from the central opening to the peripheral portion of the inductive coil assembly and wherein the second electrical lead traverses the inductive coil assembly through the channel. 
 
     
     
       2. The portable electronic device as recited in  claim 1 , further comprising an e-shield comprising an electrically conductive material disposed between the concentric loops of the inductive coil assembly and the wall, the e-shield having a slit formed through a portion of the e-shield, wherein the slit is aligned with the channel and the second electrical lead traverses the inductive coil assembly through the slit and the channel. 
     
     
       3. The portable electronic device as recited in  claim 1 , wherein the electronic component comprises a battery disposed within the device housing, the inductive coil assembly being positioned between the wall and the battery. 
     
     
       4. The portable electronic device as recited in  claim 3 , further comprising a heat-spreading layer disposed between the inductive coil assembly and the battery. 
     
     
       5. The portable electronic device as recited in  claim 4 , further comprising a shield disposed between the concentric loops of the inductive coil assembly and the wall, wherein the shield is grounded to the heat-spreading layer. 
     
     
       6. The portable electronic device as recited in  claim 5 , wherein the shield comprises tabs protruding from opposing sides of the shield that ground the shield to the heat-spreading layer. 
     
     
       7. The portable electronic device as recited in  claim 1 , further comprising:
 a battery configured to receive electrical energy from the inductive coil assembly. 
 
     
     
       8. The portable electronic device as recited in  claim 1 , wherein the portable electronic device is a battery case defining a cavity sized to receive a media device and wherein the portable electronic device includes circuitry for supplying energy to the media device from a battery of the battery case. 
     
     
       9. The portable electronic device as recited in  claim 8 , further comprising a printed circuit board having a plug connector mounted thereto, wherein the first and second electrical leads are coupled directly to the printed circuit board. 
     
     
       10. A portable electronic device, comprising:
 a device housing comprising a back wall having a channel formed in an interior-facing surface of the back wall; 
 a battery disposed within the device housing; and 
 an inductive coil assembly disposed between the interior facing surface and the battery, the inductive coil assembly comprising:
 a first electrical lead extending away from a peripheral portion of the inductive coil assembly, and 
 a second electrical lead extending from a central region of the inductive coil assembly, into the channel defined by the back wall and beneath one portion of the inductive coil assembly, the first and second electrical leads being configured to transmit electrical current induced within the inductive coil assembly to the battery; and 
 a ferrite sheet disposed between the batter and the inductive coil assembly; 
 wherein a length of the channel in the interior-facing surface of the wall extends from the central region to a peripheral portion of the inductive coil assembly and wherein the second electrical lead traverses the inductive coil assembly through the channel. 
 
 
     
     
       11. The portable electronic device as recited in  claim 10 , wherein a portion of the second electrical lead within the channel is embedded within the back wall by filling unused portions of the channel with adhesive material. 
     
     
       12. The portable electronic device as recited in  claim 10 , wherein the inductive coil assembly comprises a plurality of concentric loops forming a flat coil. 
     
     
       13. The portable electronic device as recited in  claim 10 , further comprising an e-shield disposed between concentric coils of the inductive coil assembly and the back wall of the device housing, the e-shield comprising an electrically conductive layer having a thickness of less than 50 nm and having a slit formed through a portion of the e-shield, wherein the slit is aligned with the channel and the second electrical lead traverses the inductive coil assembly through the slit and the channel. 
     
     
       14. A case for a portable electronic device, the case comprising:
 a battery; 
 a case housing defining a first cavity configured to receive the portable electronic device and a second cavity accommodating the battery, the case housing comprising a wall having a channel formed in an interior-facing surface of the wall; and 
 an inductive coil assembly coupled to the interior-facing surface and configured to receive electrical energy, the inductive coil assembly comprising:
 a first electrical lead extending away from a peripheral portion of the inductive coil assembly; and 
 a second electrical lead extending from a central region of the inductive coil assembly, into the channel defined by the wall and beneath one portion of the inductive coil assembly, the first and second electrical leads being configured to transmit electrical current induced within the inductive coil assembly to a battery. 
 
 
     
     
       15. The case as recited in  claim 14 , further comprising a shield disposed between a portion of the inductive coil assembly and the wall. 
     
     
       16. The case as recited in  claim 14 , further comprising a rigid printed circuit board (PCB), wherein the first and second electrical leads are wire bonded to the rigid PCB. 
     
     
       17. The case as recited in  claim 14 , wherein the battery is electrically coupled with the inductive coil assembly and the case further comprises a heat-spreading layer disposed between the inductive coil assembly and the battery. 
     
     
       18. The case as recited in  claim 14 , wherein the inductive coil assembly further comprises concentric loops of electrically conductive wires defining a central opening at the central region of the inductive coil assembly, and wherein the second electrical lead extends across at least a portion of the central opening.

Description:
FIELD 
     The described embodiments relate generally to wireless charging. More particularly, the present embodiments are directed towards configuring an inductive charging module in a portable electronic device. 
     BACKGROUND 
     Portable electronic devices (e.g., mobile phones, media players, electronic watches, battery cases and the like) operate when there is charge stored in their batteries. Some portable electronic devices include a rechargeable battery that can be recharged by coupling the portable electronic device to a power source through a physical connection, such as through a charging cord. Using a charging cord to charge a battery in a portable electronic device, however, requires the portable electronic device to be physically tethered to a power outlet. To avoid such shortcomings, wireless charging devices and modules have been developed to wirelessly charge portable electronic devices without the need for a charging cord. For example, some portable electronic devices can be recharged by merely resting the device on a charging surface of a wireless charging device. A transmitter coil disposed below the charging surface may produce a time-varying magnetic flux that induces a current in a corresponding receiving coil in the portable electronic device. Unfortunately, the receiving coil can take up space within the portable electronic device that can make the device more bulky and/or reduce space for other components. Consequently, ways of reducing the amount of space taken up by the receiving coil is desirable. 
     SUMMARY 
     This disclosure describes various embodiments that relate to configurations of an inductive charging receiver coil and its incorporation within a portable electronic device. 
     A portable electronic device is disclosed and includes the following: a device housing including a wall having a channel formed in an interior-facing surface of the wall; and an inductive coil assembly coupled to the interior facing surface. The inductive coil assembly includes concentric loops of electrically conductive material that define a central opening; a first electrical lead extending away from a peripheral portion of the inductive coil assembly; and a second electrical lead extending from the central opening, into the channel defined by the wall and beneath one side of the concentric loops. 
     A case for a portable electronic device is disclosed and includes the following: a battery; a case housing defining a first cavity configured to receive the portable electronic device and a second cavity accommodating the battery, the case housing comprising a wall having a channel formed in an interior-facing surface of the wall; an inductive coil assembly coupled to the interior-facing surface and configured to receive electrical energy. The inductive coil assembly includes a first electrical lead extending away from a peripheral portion of the inductive coil assembly; and a second electrical lead extending from a central region of the inductive coil assembly, into the channel defined by the wall and beneath one portion of the inductive coil assembly, the first and second electrical leads being configured to transmit electrical current induced within the inductive coil assembly to the battery. 
     Another portable electronic device is disclosed and includes the following: a device housing including a back wall having a channel formed in an interior-facing surface of the back wall; a battery disposed within the device housing; and an inductive coil assembly coupled to the interior facing surface and positioned between the battery and the back wall. The inductive coil assembly includes the following: a first electrical lead extending away from a peripheral portion of the inductive coil assembly; and a second electrical lead extending from a central region of the inductive coil assembly, into the channel defined by the back wall and beneath one portion of the inductive coil assembly. The first and second electrical leads are configured to transmit electrical current induced within the inductive coil assembly to the battery. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  is a block diagram illustrating an exemplary portable electronic device, an exemplary power supplying apparatus for coupling with the exemplary portable electronic device to charge the exemplary portable electronic device; 
         FIG. 2  illustrates an exemplary wireless charging system during wireless power transfer; 
         FIG. 3A  shows an exploded perspective view of an exemplary portable electronic device taking the form of a battery case that includes a wireless charging assembly for wirelessly receiving electrical energy and an energy storage device; 
         FIG. 3B  shows a perspective view of an electronic device disposed within a primary cavity of the battery case depicted in  FIG. 3A ; 
         FIG. 4  shows a cross-sectional side view of an electronic device disposed within the battery case depicted in  FIGS. 3A-3B  in accordance with section line A-A from  FIG. 3B ; 
         FIG. 5A  shows a perspective view of a wall-facing side of an inductive coil assembly; 
         FIG. 5B  shows an alternative embodiment in which an electrical lead crosses across a portion of a central opening of the inductive coil assembly; 
         FIG. 5C  shows a perspective view of an inductive coil assembly along with a cross-sectional view of a loop of inductive coil assembly  308  in accordance with section line B-B; 
         FIG. 6A  shows a perspective view of an e-shield assembly; 
         FIG. 6B  shows a cross-sectional view of a wireless charging assembly and how termination contacts and tabs of an e-shield assembly can curve upwards to be electrically coupled with portions of an electrically conductive heat-spreading layer; and 
         FIG. 7  shows a flow chart describing a method for installing an inductive charging coil within a device housing. 
     
    
    
     DETAILED DESCRIPTION 
     Representative applications of methods and apparatus according to the present application are described in this section. These examples are being provided solely to add context and aid in the understanding of the described embodiments. It will thus be apparent to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are possible, such that the following examples should not be taken as limiting. 
     In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting; such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. 
     A portable electronic devices is an electronic device that can operate without being coupled to a power grid by running on its own using locally stored electrical power. The portable electronic device can be specifically designed to perform various functions for a user. In some embodiments, an accessory device can include an auxiliary battery for extending the useful operating time of the portable electronic device. In order to also provide robust protection of the portable electronic device the accessory device can surround most exterior surfaces of the portable electronic device and in some instances make access to ports difficult. For this reason, it can be desirable to include a wireless energy receiving coil in an accessory device for ease of charging; however, adding additional circuitry to the accessory device may reduce an amount of space available for battery volume, or can unduly increase the size of the accessory device. 
     One way to add wireless charging to the accessory device without unduly reducing space available for the battery or other components is to partially embed the wireless energy receiving coil into a wall of the accessory device. In this way, an amount of space taken up within the accessory device can be reduced. Other efficiencies can be achieved by forming the wireless energy receiving coil as a flat coil formed from stranded wires making for an overall thickness of less than 250 microns. 
     In some embodiments, the wireless energy receiving coil can be part of an inductive charging coil assembly that includes a shield for reducing capacitive noise generated during a wireless charging operation. The shield can include tabs with termination contacts for grounding the shield to an electrically conductive heat-spreading layer positioned above the inductive charging coil assembly. 
     These and other embodiments are discussed below with reference to  FIGS. 1-7 ; however, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  is a block diagram illustrating an exemplary portable electronic device  100 , an exemplary power supplying apparatus  119  for coupling with device  100  to charge device  100 , according to some embodiments of the present disclosure. Device  100  includes a computing system  102  coupled to a memory bank  104 . Computing system  102  can include control circuitry configured to execute instructions stored in memory bank  104  for performing a plurality of functions for operating device  100 . The control circuitry can include one or more suitable computing devices, such as microprocessors, computer processing units (CPUs), graphics processing units (GPUs), field programmable gate arrays (FPGAs), and the like. 
     Computing system  102  can also be coupled to a user interface system  106 , a communication system  108 , and a sensor system  110  for enabling electronic device  100  to perform one or more functions. For instance, user interface system  106  can include a display, speaker, microphone, actuator for enabling haptic feedback, and one or more input devices such as a button, switch, capacitive screen for enabling the display to be touch sensitive, and the like. Communication system  108  can include wireless telecommunication components, Bluetooth components, and/or wireless fidelity (WiFi) components for enabling device  100  to make phone calls, interact with wireless accessories, and access the Internet. Sensor system  110  can include light sensors, accelerometers, gyroscopes, temperature sensors, and any other type of sensor that can measure a parameter of an external entity and/or environment. 
     All of these electrical components require a power source to operate. Accordingly, electronic device  100  also includes a battery  112  for discharging stored energy to power the electrical components of device  100 . To replenish the energy discharged to power the electrical components, electronic device  100  includes a wireless charging system  118 . Wireless charging system  118  can include charging circuitry  114  and receiver/transmitter coil  116  for receiving power from a wireless charging device  120  coupled to an external power source  122 . Wireless charging device  120  can include a transmitter coil for generating a time-varying magnetic flux capable of generating a corresponding current in receiver coil  116 . The generated current can be utilized by charging circuitry  114  to charge battery  112 . 
       FIG. 2  illustrates an exemplary wireless charging system during wireless power transfer. Specifically,  FIG. 2  illustrates the electrical interactions experienced by an exemplary wireless charging system as it is receiving power from a wireless charging device. A portable electronic device  204  is positioned on a charging surface  212  of a wireless charging device  202 . Portable electronic device  204  can include a wireless charging system  207  that has a receiver/transmitter coil  208  and charging circuitry  205 ; and wireless charging device  202  can include a transmitter coil  206 . Receiver coil  208  can be an inductor coil that can interact with and/or generate time-varying magnetic flux. Electronic device  204  can be a consumer electronic device, such as a smart phone, tablet, battery case and the like. Wireless charging device  202  can be any suitable device configured to generate time-varying magnetic field to induce a corresponding current in a receiving device. For instance, wireless charging device  202  can be a wireless charging mat, puck, docking station, and the like. Electronic device  204  may rest on the wireless charging device  202  at charging surface  212  to enable power transfer. 
     During wireless power transfer from wireless charging device  202  to portable electronic device  204 , wireless charging system  207  can operate to receive power from wireless charging device  202 . For instance, charging circuitry  205  can operate receiving coil  208  as a receiving coil to receive power by interacting with time-varying magnetic flux  210  generated by transmitter coil  206 . Charging circuitry  205  can correspond with charging circuitry  114  in  FIG. 1 . Interaction with time-varying magnetic flux  210  results in an inducement of current in hybrid receiver/transmitter coil  208 , which can be used by charging circuitry  205  to charge an internal battery of portable electronic device  204 . As shown in  FIG. 2 , portable electronic device  204  can rest on charging surface  212  of wireless charging device  202 . In some embodiments, an interface surface  220  of portable electronic device  204  makes contact with charging surface  212  during wireless power transfer. Thus, portable electronic device  204  can receive power through interface surface  220 . Interface surface  220  can be an external surface of a housing of portable electronic device  204 . 
       FIG. 3A  shows an exploded perspective view of an exemplary portable electronic device taking the form of battery case  300  that includes a wireless charging assembly  302  for wirelessly receiving electrical energy and an energy storage device such as a capacitor or battery  304 . Wireless charging assembly  302  can include E-shield assembly  306 , inductive coil assembly  308 , base ferrite layer  310 , and heat-spreading layer  312 . In particular, battery case  300  includes a case housing  314  made up of multiple sidewalls  316  defining a primary cavity  318  and a secondary cavity  320 . A portion of secondary cavity  320  can also include a back wall  321  that helps enclose secondary cavity  320 . Primary cavity  318  can be configured to receive a portable electronic device along the lines of a cellular phone or media device. Secondary cavity  320  can be configured to receive battery  304  and wireless charging assembly  302 . In some embodiments, secondary cavity  306  can be sealed, thereby keeping circuitry of battery case  300  separated from an electronic device disposed within cavity  318 . 
       FIG. 3A  also shows how inductive coil assembly  308  can include input and output electrical leads  322  configured to form a circuit through which electrical current generated within inductive coil assembly  308  can flow. In particular, electrical leads  322  can be electrically coupled with contacts  324  on printed circuit board (PCB)  326 . In some embodiments, slot or channel  323  can be defined by back wall  321  allowing for one of electrical leads  322  to pass beneath inductive charging assembly  308 . While component level detail of PCB  326  is not depicted it should be appreciated that PCB  326  can include a connector that routes power received by PCB  326  to battery  304 . PCB  326  can also include plug receptacle  328 . Plug receptacle  328  can be aligned with receptacle plug opening  330  and configured to allow battery case  300  to receive power from a cable when a wireless charger is not available or wired power is preferred due for power transfer efficiency reasons. In this way, PCB  326  can be configured to transfer power received either wirelessly or through a cable to battery  304 . In some embodiments, PCB  326  can have connectors configured to route power received directly to an electronic device positioned within cavity  318 . For example, a connector plug  332 , which protrudes into cavity  318  and is configured to engage a plug receptacle of an electronic device disposed within cavity  318 , can deliver power to the electronic device directly from battery  304  as well as from wired or wireless power receiving subsystems of battery case  300 . 
       FIG. 3A  shows E-shield assembly  306  having a geometry that substantially matches a size and shape of inductive coil assembly  308 . E-shield assembly  306  differs in that it includes a slot  334  for accommodating the routing of electrical lead  322 - 2  beneath the coils making up inductive coil assembly  308 . E-shield assembly  306  can be formed from multiple layers that include a thin electrically conductive layer sandwiched between two electrically insulating layers. For example, a bottom layer of E-shield assembly  306  could take the form of a layer of pressure sensitive adhesive (PSA) that acts both to adhere e-shield assembly  306  to back wall  321  of case housing  314  and to electrically insulate the thin conductive layer from the back wall  321  of case housing  314 . A top layer of e-shield assembly  306  can be formed from a polymer such as polyethylene terephthalate (PET) in some embodiments and electrically insulate the thin conductive layer from inductive coil assembly  308 . In some embodiments, the thin conductive layer can be less than 50 nm thick. In one particular configuration, a thickness of the thin conductive layer can be between 5 and 15 nanometers thick. The thin conductive layer can be deposited upon the PET layer using a PVD process. The thin conductive layer can be configured to operate as a capacitive shield that decouples capacitive noise generated along a downward facing surface of inductive coil assembly  308  during a wireless charging operation. An overall thickness of e-shield assembly  306  can be between 15 and 20 microns. 
     In some embodiments, inductive coil assembly  308  is depicted as a flat coil and can be formed from wound copper coil encased at least in part by one of a polyurethane or polyimide coating. It should be appreciated that inductive coil assembly  308  could also take the form of a helical coil. In some embodiments, the inductive coil assembly  308  can have an inner diameter of 19 mm and an outer diameter of 47 mm. Base ferrite layer  310  can be made up of multiple layers that include a layer formed of an iron alloy sandwiched between a layer of PET and a layer of pressure sensitive adhesive (PSA). The layer of PSA can be configured to affix base ferrite layer  310  to inductive coil assembly  308  and in some embodiments to a periphery of e-shield assembly  306 . Base ferrite layer  310  can be configured to prevent a magnetic field inducing current in inductive coil assembly  308  from penetrating farther into battery case  300 . Heat-spreading layer  312  can be configured to spread heat generated during wireless charging across a lower surface of battery  304  to prevent over heating a small region of battery  304  positioned directly above inductive coil assembly  308 . In some embodiments, heat=spreading layer  312  can also be configured to receive or transmit heat to printed circuit board (PCB)  326 . Heat-spreading layer  312  can also include a notch  336  for accommodating the height of plug receptacle  328 , which can be surface mounted to PCB  326 . Heat-spreading layer  312  can be adhesively coupled to base ferrite layer  310 . 
       FIG. 3B  shows a perspective view of an electronic device  350  disposed within a primary cavity of battery case  300 . In some embodiments, a wireless charging assembly similar to wireless charging assembly  302  can be incorporated within electronic device  700 . For example, a back wall of electronic device  700  can include a slot or channel for accommodating the routing of one of the electrical leads of an inductive coil assembly beneath concentric loops of the inductive coil assembly. Electronic device  350  includes a data/charging port configured to receive electricity from energy stored within battery case  300  by way of a connector plug  332  (see  FIG. 3A ). In this way, energy received by battery case  300  through either receptacle plug opening  330  or wireless charging assembly  302  can be routed to a battery within electronic device  350 . 
       FIG. 4  shows a cross-sectional side view of electronic device  350  disposed within battery case  300  in accordance with section line A-A from  FIG. 3B . In particular, electronic device  350  is depicted as being engaged by and electrically coupled with connector plug  332 . Connector plug  332  is in turn electrically coupled with PCB  326  by electrically conductive pathway  401 .  FIG. 4  also includes a cross-sectional side view of wireless charging assembly  302  positioned upon and partially within back wall  321  and beneath battery  304 . A section of electrical lead  322 - 2  is shown extending beneath one side of inductive coil assembly  308 . By embedding the section of electrical lead  322 - 2  below inductive coil assembly  308  the section of electrical lead  322 - 2  can be routed out of a central region of inductive coil assembly  308  without increasing the height of inductive coil assembly. Unused portions of slot  323  can be filled by adhesive compound  404  both above and below electrical lead  322 - 2 , thereby preventing a structural integrity of back wall  321  from being compromised. Slot  323  can have a depth that exceeds half or even two thirds of a total thickness of back wall  321 . In some embodiments, the total wall thickness  406  of back wall  321  can be about 0.75 mm and a depth  408  of the slot can be about 0.5 mm. Depth  408  of slot  323  allows electrical lead  322 - 2  to be sufficiently separated from the concentric loops making up inductive coil assembly  308  to prevent or at least ameliorate any cross-talk between the section of electrical lead  322 - 2  and the concentric loops of inductive coil assembly  308 . 
     While the aforementioned inductive coil assembly is depicted as being incorporated within a battery case it should be appreciated that the inductive coil assembly can be positioned within other types of devices in a similar configuration. For example, a laptop having a radio transparent housing component or radio transparent window could also incorporate an inductive coil assembly where an electrical lead extending from a central region of the inductive coil assembly is embedded within a channel formed by the radio transparent housing component or window. Other exemplary implementations can include incorporation of an inductive charging coil within a supporting foot of a monitor device or all-in-one computing device, where the supporting foot supports the weight of the device above a supporting surface. The inductive charging coil can be incorporated within a horizontal or substantially horizontal surface (i.e. having an incline of less than 5%) of the supporting foot. In some embodiments, it can be desirable to keep a thickness of a portion of the supporting foot defining the horizontal surface minimized for cosmetic or space accommodation reasons. In order to maintain the thickness of the foot a thickness of a charging component incorporated into the horizontal surface can be minimized by embedding one of the leads of the inductive charging coil within a radio transparent wall of the supporting foot. In some embodiments, the inductive charging assembly can be integrated with other inductive charging assemblies to form an inductive charging mat on the horizontal surface of the supporting foot or the laptop device. In some embodiments, the battery case described above could be a case without a battery and simply configured to provide operating power and/or charge a battery of a device disposed within the case. 
       FIG. 5A  shows a perspective view of a wall-facing side of inductive coil assembly  308 . Concentric loops  502  making up Inductive coil assembly  308  can have an outer diameter of about 45-50 mm and an inner diameter of about 15-20 mm. In particular, electrical lead  322 - 2  is shown being folded over and extending from a central opening  502  defined by concentric loops  502  and over the top of multiple concentric loops  502  until reaching a periphery of inductive coil assembly  308 . After reaching the periphery, electrical lead  322 - 2  bends down again so that both of electrical leads  322  are in the same plane as concentric loops  502  of inductive coil assembly  308 .  FIG. 5B  shows a variation in which electrical lead  322 - 2  crosses across a portion of central opening  504 . Routing electrical lead  322 - 2  across central opening  502  allows a total inductance of inductive coil assembly  308  to be optimized by reducing a total amount of wire required to form an inductive coil of the depicted size on account of electrical lead  322 - 2 . The length of the wires making up inductive coil assembly  308  is reduced due to it not having to extend as far around a periphery of central opening  502 . 
       FIG. 5C  shows a perspective view of inductive coil assembly  308  along with a cross-sectional view of a loop of inductive coil assembly  308  in accordance with section line B-B. The cross-sectional view shows how each concentric loop  502  can include five parallel stranded wires. Each of stranded wires  508  can have a diameter of about 200 microns and be formed from multiple smaller wires  510  twisted together. In some embodiments, this stranded wire configuration can increase an efficiency with which inductive coil assembly is able to receive energy from a magnetic field generated by a charging device. Stranded wires  508  can be wrapped in a protective layer  512  made of polyurethane and/or polyamide to prevent interaction between the concentric loops making up inductive coil assembly  308 . In some embodiments, each individual stranded wire  508  can be wrapped in electrically insulating layers of polyurethane and/or polyamide material. In this way, undesired interaction between adjacent stranded wires  508  can be avoided. 
       FIG. 6A  shows a perspective view of e-shield assembly  306 . E-shield assembly  306  has an annular geometry sized to match a size and shape of inductive coil assembly  308 . E-shield assembly  306  includes termination contacts  602  on opposing tabs of e-shield assembly  306 . Termination contacts  602  create pathways through which e-shield assembly  306  can be grounded. The close up view of the edge of e-shield assembly  306  shows an electrically conductive layer  606  sandwiched between two electrically insulating layers  608  and  610  forming e-shield assembly  306 . In some embodiments, electrically conductive layer  606  can be silver and formed by a physical vapor deposition process. A thickness of electrically conductive layer  606  can be between 5 nm and 15 nm. The use of a thin electrically conductive layer as a capacitive shield can remove capacitive noise from inductive coil assembly  308  without substantially impairing the transfer of charging energy through e-shield assembly  306 . Electrically insulating layer  608  can be formed from PET and have a thickness of between 7 and 17 microns. Electrically insulating layer  610  can take the form of a layer of pressure sensitive adhesive and have a thickness of between 3 and 7 microns. The pressure sensitive adhesive can be well suited for attaching e-shield assembly  306  to back wall  321  (not depicted) of case housing  314 . In some embodiments, termination contacts  602  can be formed by removing portions of electrically insulating layer  608  to expose portions of electrically conductive layer  606 . 
       FIG. 6B  shows a cross-sectional view of wireless charging assembly  302  and how termination contacts  602  and tabs  604  of e-shield assembly  306  can curve upwards to be electrically coupled with portions of electrically conductive heat-spreading layer  312 . Termination contacts  602  can be secured to heat-spreading layer  312  by copper tape that establishes a secure adhesive coupling and maintains an electrically conductive and thermally conductive pathway between the components. In some embodiments, heat-spreading layer  312  can be formed from pyrolytic graphite sheets (PGS), which can be effective at both dissipating heat and acting as an electrically conductive ground plane for e-shield assembly  306 . Heat-spreading layer  312  can have a thickness of about 60 microns sufficient to evenly distribute heat generated by inductive charging assembly  302  to avoid unduly heating localized portions of a battery (not depicted) positioned above heat-spreading layer  312 . In some embodiments, peripheral edges of heat-spreading layer  312  can be compressed against tabs  604  by a cowling that maintains positive pressure that cooperates with the copper tape to maintain the peripheral edges of heat-spreading layer  312  in robust thermally and electrically conductive contact with termination contacts  602  of tabs  604 . 
       FIG. 7  shows a flow chart  700  describing a method for installing an inductive charging coil within a device housing. At  702 , a channel is formed within an interior-facing surface of a back wall of a device housing. In some embodiments, the channel can have a depth of more than half of a thickness of the back wall of the device housing. The channel can be formed by a subtractive machining operation in which material is removed from the back wall of the device housing. In some embodiments, the device housing can be associated with a portable electronic device or a device accessory along the lines of a battery case. At  704 , a shield element can be coupled to the interior-facing surface of the back wall. The shield element can define a slot that allows the shield element to be positioned on both sides of the channel while leaving the channel uncovered. At  706 , a first layer of adhesive can be added to the channel. At  708 , an electrical lead that originates from a central region of an inductive coil assembly can have a portion that is positioned within the channel. The first layer of adhesive within the channel can help keep the electrical lead in place within the channel. At  710 , the electrical lead can be covered with a second layer of adhesive. The second layer of adhesive can fill or at least substantially fill the channel. By filling the channel with multiple layers of adhesive and the electrical lead of the inductive coil assembly, a consistency and strength of the back wall of the device housing can be maintained, with a portion of the electrical lead being embedded within the back wall. At  712 , the inductive coil can be secured to the shield in a position that results in the embedded portion of the leave being positioned beneath one side of the inductive coil. The second layer of adhesive can help prevent interaction between concentric loops of the inductive coil assembly and the portion of the electrical lead embedded within the back wall. In this way, the inductive coil can lay flat on the interior-facing surface of the back wall with an effective thickness equivalent to a thickness of a single wire used to form the concentric loops making up the inductive coil assembly. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium for controlling a manufacturing line. The computer readable medium is any data storage device that can store data, which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20180911
Publication Date: 20200728
Grant Date: 20200728
Priority Date: 20180911
Inventors: LARSSON, KARL RUBEN FREDRIK
GRAHAM, Christopher S.
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J7/0042", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F27/361", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/361", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/361", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/36", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/181", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1632", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0042", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/181", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 69718931