PATENT DOCUMENT

Publication Number: US-10498159-B2
Application Number: US-201615156225-A
Country: US
Kind Code: B2

Title: Variable diameter coil for efficient inductive charging

Abstract:
This application relates to inductive charging coil configurations. In particular, the wireless charging coil configurations are arranged in a shape and size suitable for utilizing available space within a device housing. In some embodiments, wires making up the charging coil have varying diameters configured to optimize the size and shape of the charging coil so that available space can be fully utilized.

Claims:
What is claimed is: 
     
       1. A wireless charging coil, comprising:
 an electrically conductive conduit, comprising:
 first and second loops spaced apart from each other, the first loop formed from a first wire portion having a first wire diameter and the second loop formed from a second wire portion having a second wire diameter greater than the first wire diameter, the first and second loops being configured to receive power by induction. 
 
 
     
     
       2. The wireless charging coil of  claim 1 , wherein each of the first and second wire portions are wire bundles. 
     
     
       3. The wireless charging coil of  claim 1 , wherein a thickness of the wireless charging coil is greater in a central portion of the wireless charging coil than in a peripheral portion of the wireless charging coil. 
     
     
       4. The wireless charging coil of  claim 1 , wherein the first wire portion comprises a first plurality of wires and the second wire portion comprises a second plurality of wires and the first plurality of wires has the same number of wires as the second plurality of wires. 
     
     
       5. The wireless charging coil of  claim 1 , wherein the second loop includes a greater number of wires than the first loop. 
     
     
       6. The wireless charging coil of  claim 1 , wherein the first wire diameter is an outer diameter of a bundle of wires. 
     
     
       7. A portable electronic device, comprising:
 a device housing comprising a wall defining a concave recess within the device housing; and 
 a charging coil, comprising an electrically conductive conduit arranged in a plurality of loops, an average outer diameter of a first portion of the electrically conductive conduit arranged in a central portion of the concave recess being greater than an average outer diameter of a second portion of the electrically conductive conduit that is arranged in a peripheral portion of the concave recess. 
 
     
     
       8. The portable electronic device of  claim 7 , wherein the average outer diameter of the electrically conductive conduit varies in a way that causes the first portion of the electrically conductive conduit to extend substantially the same distance from the concave recess as the second portion of the conduit. 
     
     
       9. The portable electronic device of  claim 7 , wherein the electrically conductive conduit comprises a plurality of wires twisted together. 
     
     
       10. The portable electronic device of  claim 9 , wherein a greater number of wires are twisted together in the first portion of the electrically conductive conduit than in the second portion of the electrically conductive conduit. 
     
     
       11. The portable electronic device of  claim 7 , wherein at least a portion of the wall defining the concave recess is formed from a magnetically permeable material. 
     
     
       12. The portable electronic device of  claim 7 , wherein the electrically conductive conduit comprises a first segment having an increasing diameter and a second segment having a decreasing diameter. 
     
     
       13. The portable electronic device of  claim 7 , wherein the electrically conductive conduit comprises a first segment and a second segment, the first segment having a greater number of wires than the second segment. 
     
     
       14. The portable electronic device of  claim 7 , wherein the charging coil has a substantially circular geometry. 
     
     
       15. A charging coil, comprising:
 an electrically conductive conduit, comprising:
 a first wire having a first length, and 
 a second wire having a second length less than the first length, the second wire being coupled with a portion of the first wire disposed in a central portion of the charging coil, wherein the electrically conductive conduit is arranged in a plurality of loops such that an average outer diameter of a first segment of the electrically conductive conduit is different than an average outer diameter of a second segment of the electrically conductive conduit, the first and second wires being configured to receive power by induction. 
 
 
     
     
       16. The charging coil of  claim 15 , wherein the second segment of the electrically conductive conduit is position at a peripheral portion of the charging coil and has a substantially smaller average outer diameter than the central portion of the charging coil. 
     
     
       17. The charging coil of  claim 15 , wherein the average outer diameter of the first segment is greater than the average outer diameter of the second segment. 
     
     
       18. The charging coil of  claim 17 , wherein the second segment of the first wire is disposed within the central portion of the charging coil. 
     
     
       19. The charging coil of  claim 15 , wherein the first and second wires are formed from a copper alloy.

Description:
FIELD 
     The described embodiments relate generally to inductive charging. More particularly, the present embodiments are directed towards methods and apparatus for designing inductive charging coils capable of occupying most or all available space within device housings having irregular internal geometries. 
     BACKGROUND 
     Portable electronic devices often are enclosed within small form factor housings to make carrying and/or wearing the devices more convenient. Unfortunately, this makes the efficient utilization of space available within the housings of great importance. Some housings include various protrusions and/or recesses that make the device more comfortable to wear or enhance the overall function of a particular sensor. These irregularly shaped protrusions and recesses can result in empty space within the housings that goes unutilized. 
     SUMMARY 
     This disclosure describes various embodiments that relate to ways in which components can be efficiently arranged within a device housing to improve the performance of the device without increasing the size of the device housing. 
     A wireless charging coil is disclosed that can include first and second loops with the first loop arranged along a peripheral portion of the charging coil and the second loop arranged within a central portion of the charging coil. Alternatively, the position of the loops can be reversed to suit different devices. The first loop can be formed from one or more wires having a first wire diameter and the second loop can be formed from one or more wires having a second wire diameter greater than the first wire diameter. 
     A portable electronic device is disclosed that includes a device housing having a wall defining a concave recess within the device housing. The portable electronic device also includes a charging coil having a variable diameter electrically conductive conduit arranged in multiple loops, an average outer diameter of a first portion of the conduit arranged in a central portion of the concave recess being greater than an average outer diameter of a second portion of the conduit that is arranged in a peripheral portion of the concave recess. In some embodiments, other non-conventional recesses and protrusions within the device housing can be accommodated by varying the outer diameter of the conduit so that space around the protrusion or recess can be fully utilized. 
     Another charging coil is disclosed and includes an electrically conductive conduit having a first wire of a first length, and a second wire of a second length less than the first length. The second wire is electrically coupled with a portion of the first wire disposed in a central portion of the charging coil. The electrically conductive conduit is arranged in multiple loops. By using wires of varying length, all the wires can begin and end at the same point while the shorter whiles can bypass a peripheral portion of the coil and be included only in the more central portions of the charging coil. 
    
    
     
       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. 1A  shows a device having a device housing that includes a protruding wall designed to accommodate a sensor; 
         FIG. 1B  shows how by gradually increasing the outer diameter of each loop of a charging coil the space between a protruding wall of the device housing and an operational component can be more efficiently utilized; 
         FIG. 1C  shows how varying the diameter of wires making up a charging coil can also maximize wire density when the charging coil is configured to be positioned proximate a convex surface; 
         FIG. 2A  shows a portion of a charging coil and depicts an offset between two section lines; 
         FIGS. 2B-2C  show cross-sectional views of one section of the charging coil depicted in  FIG. 2A  and formed from multiple wires; 
         FIG. 2D  shows how the diameter of each individual wire making up the coil can vary; 
         FIG. 3A  shows a top view of an exemplary charging coil; 
         FIG. 3B  shows a cross-sectional view of a portion of the exemplary charging coil in accordance with a section line; 
         FIG. 4A  shows a charging coil formed from a wire drawn in a way that causes it to have a varying diameter to match the desired height of the space available for the charging coil; 
         FIG. 4B  shows a cross-sectional view of one side of each loop of the charging coil and how the diameter of the wire is different for adjacent loops; 
         FIG. 4C  depicts an alternative embodiment in which each loop is formed from multiple wires that gradually get larger and smaller together to more substantially increase and decrease the outer diameter of each loop 
         FIG. 4D  shows a charging coil formed from a bundle of wires having varying diameters; 
         FIG. 4E  shows another charging coil formed from a wire drawn in a way that causes it to have a varying diameter; 
         FIG. 4F  shows a cross-sectional view of one side of each loop of the charging coil depicted in  FIG. 4E ; 
         FIG. 5  shows a top view of a charging coil in which different length wires can be joined together and overlap one another so that a central portion of the charging coil is substantially thicker than a peripheral portion of the charging coil; 
         FIGS. 6A-6D  show perspective views of various wire configurations; and 
         FIG. 7  shows a flow chart depicting a method of forming a variable diameter wire used in a charging coil. 
     
    
    
     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. 
     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 device can take many different sizes and shapes. The integration of biometric sensors within the portable electronic device can influence the design. For example, a portion of a device housing can be shaped to protrude from the device housing so that a sensor positioned upon the device housing and in contact with a user can be pressed more firmly against the skin of the user. These protrusions often leave space within the device, which is difficult to efficiently fill with conventional components. Alternatively, various exterior features of a device can be shaped primarily for aesthetic purposes. For example, sidewalls of a device housing can be curved to make the device housing more comfortable in the hand. Again curved surfaces can create curved recesses that can be challenging to fully utilize. 
     One solution to this problem is to customize the shape and size of one or more internal device components to conform to the shape and size of any irregularities (e.g. recesses or protrusions) of the device housing. For example, a wireless charging coil can be modified so that instead of having a uniform thickness, a central portion of the coil has an increased thickness to take advantage of the additional space made available by a protruding portion of the device housing. Similarly, a device housing can have a recessed exterior surface defined by a housing wall that forms a convex protrusion extending into the interior of the device housing. In such a case, peripheral portions of the coil can be increased to take advantage of the peripheral areas of the device housing that have additional space for accommodating the expanded interior space within the device housing. 
     These and other embodiments are discussed below with reference to  FIGS. 1A-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. 1A  shows a device  100  having a device housing  102  that includes a protruding wall  104  designed to accommodate a sensor  106 . In some embodiments, sensor  106  can include a magnetic element designed to facilitate the alignment of a wireless charger with an exterior surface of device  1010 . Device  100  can take many forms including, e.g. a cellular phone, a media player, a wearable device, etc. Charging coil  108   a  is depicted being adhered to or proximate an interior facing surface of protruding wall  104 . Charging coil  108   a  includes one or more coiled wires arranged in multiple loops and can be configured to receive electricity wirelessly through protruding wall  104 . In some embodiments, each of the wires can be made from a copper alloy. For this reason, at least a portion of protruding wall  104  can be made of a magnetically permeable material such as, for example, glass or polymer based substrates. In this way, the energy transferring magnetic field emitted by the charging device can pass efficiently through protruding wall  104 . Loops of charging coil  108  can take the form of an electrically conductive conduit formed of one or more wires and can have a substantially uniform outer diameter. The loops of charging coil  108  that are positioned closer to a central portion of protruding wall  104  are positioned increasingly farther from operational component  110 , on account of operational component  110  having a substantially planar surface facing charging coil  108 . Operational component  110  can take many forms, including for example an electronic assembly including one or more of an integrated circuit, a data storage medium and a battery. Because of the substantially planar lower surface of operational component  110 , spaces  111  between the more central loops of charging coil  108  and operational component  110  go unused. A benefit of the rectangular shape of operational component  110  is that it provides a conforming support surface for display assembly  112 , which also has a substantially rectangular geometry. It should be noted that while the loops of charging coil  108  are shown being separated by a gap, each of the loops forming charging coil  108  can also be arranged more closely together so that adjacent coils are pressed firmly together, thereby increasing the packing efficiency of the coils arranged within the device housing. 
       FIG. 1B  shows how by gradually increasing the outer diameter of each loop of charging coil  108   b  the space between protruding wall  104  and operational component  110  can be more efficiently utilized. The gradually increasing outer diameter of charging coil  108   b  can reduce the impedance within charging coil  108   b , thereby increasing the efficiency with which charging coil  108   b  can receive electrical energy. While a single row of coils is shown, it should also be appreciated that multiple rows of smaller coils can be stacked together to achieve similar configurations. Charging coils with increasing diameters also have the benefit of reducing space within which individuals loops of charging coil  108   b  can shift during use. In this way, charging coil  108   b  can receive a predictable amount of electricity from a charging device. Additionally, on account of charging coil  108   b  utilizing more of the space between protruding wall  104  and operational component  110 , charging coil  108   b  can provide support to a bottom portion of operational component  110 . In some embodiments, operational component  110  can compress charging coil  108   b  against an interior facing surface of device housing  102 .  FIG. 1B  also depicts how battery assembly  113  can be integrated into operation al component  110  and electrically coupled with charging coil  108   b.    
       FIG. 1C  shows how a charging device  114  can also include varying coil sizes arranged to conform with a convex surface and maximize wire density within charging device  114 . Charging device  114  can also include one or more internal magnets  118  for aligning charging device  114  with electronic device  100 . Internal magnets  118  can be configured to cooperate with magnetic elements of electronic device  100 . In some embodiments, magnets can be arranged within or proximate sensor  106  to achieve a positive alignment between charging coil  116  and charging coil  108   b .  FIG. 1C  also depicts how charging device  114  includes other supporting electrical components such as power source  122 . Power source  122  can be configured to condition power entering charging device  114  through cable  124 . For example, AC power received from a wall outlet could be converted to DC power in some applications. In some embodiments, power source  122  can be operative to adjust the voltage of the power being received. Power source  122  is configured to supply conditioned power to charging coil  116 , processing unit  126  and storage medium  128 . In some embodiments, cable  124  is configured to transmit both power and data to charging device  114 . Processing unit  126  can then determine how to adjust operation of charging device  114  in accordance with any control signals received by way of cable  124 . For example, power supplied to charging coil  116  could be modulated in accordance with instructions executed by processing unit  126 . Storage medium  128  can be configured to store instructions for later execution. In some embodiments, the information stored in storage medium  128  can govern standard operations of charging device  114 . In some embodiments, firmware updates could be applied to data stored in storage medium  128 . 
       FIG. 2A  shows a top view of a charging coil  200  made up of a bundle of wires and a close up view of a portion of charging coil  200 . Section lines A-A and B-B are represented in the closeup view to indicate two different regions of the portion of charging coil  200 .  FIGS. 2B-2C  show cross-sectional views of the portion of the charging coil depicted in  FIG. 2A  in accordance with section lines A-A and B-B respectively.  FIGS. 2B and 2C  show how wires  202  of charging coil  200  have substantially the same diameter. In some embodiments, wires  202  can be arranged in parallel while in other embodiments the wires can be twisted together. In some instances, the bundle of wires  202  cooperating to form this portion of the charging coil can be referred to as a conduit, which as depicted has an outer diameter  203 .  FIG. 2B  shows how in the distance between section lines A-A and B-B wires  202  can rotate along a length of the section of coil when twisted about one another by an angle of about 45 degrees. 
       FIG. 2D  shows how the diameter of each individual wire making up the coil can vary. For example, a diameter of wire  204  can be substantially larger than a diameter of wire  206 . By varying the diameter of the individual wires, the current density can be biased towards a desired side of the wire. In addition to biasing current density the smaller diameter wires help to fill in the cross-section of the wire so there is less empty space within the wire cross-section. In some embodiments, the wires can be enclosed within insulating layer  208 . Insulating layer  208  can prevent wires arranged along an exterior portion of the conduit from contacting adjacent wires associated with another portion of the conduit. In this way, shorting can be prevented. 
       FIG. 3A  shows a top view of exemplary charging coil  300 . Charging coil  300  can include positive lead  302  and negative lead  304 , which can be electrically coupled with a battery or similar energy storage device. Charging coil  300  shows one way in which central portions of the charging coil can be made thicker than other portions of the charging coil. In this depiction a central portion of the conduit includes as many as three wires, which increase the outer diameter of that portion of the charging coil. While the three wires are depicted as being parallel to one another this configuration is made for illustrative purposes only and it should be appreciated that the coils could be vertically stacked and/or twisted about one another to increase the number of coils that can be arranged within the constrained space.  FIG. 3A  also illustrates how the central portion of the coil is designed to include more wires by adding a shorter wire to only the central loops of charging coil  300 . The ends of each of the shorter wires can be melted or soldered to longer wires so that electricity traveling on the shorter wires can easily transition between the shorter wires and the longer wires without adding a substantial amount of impedance to the charging coil. 
       FIG. 3B  shows a cross-sectional view of a portion of charging coil  300  in accordance with section line C-C and how each of wires  202  can be stacked together in discrete loops spaced apart from adjacent loops and atop an interior-facing, sloped surface of housing  102 . In particular, each of the single wires depicted in  FIG. 3A  represents multiple smaller wires. Instead of arranging the wires side-by-side as was implied by  FIG. 3A ,  FIG. 3B  shows how the wires are grouped together in increasingly taller loops groups, making a height of each discrete grouping of wires about the same height. Each loop is depicted containing an increasingly large number of wires. The beginning and end of each of the shorter wires can be welded and/or fused to adjacent wires so that electricity can flow out of the terminated wire and into the smaller set of wires. 
       FIG. 4A  shows a configuration of charging coil  400  in which a wire has a varying diameter to match the desired height of the space available for the charging coil. This can be accomplished by drawing different portions of the wire through differing diameter apertures or by changing a diameter of an aperture through which the wire is drawn. In this way, a single wire having a varying diameter can be used to maximize an amount of space available within an associated device housing. As depicted, charging coil  400  includes leads  401  and  402 . In particular, lead  402  can be configured to pass over loops of charging coil  400 . A diameter of either lead  402  and/or the loops it overlaps can be adjusted to accommodate lead  402 . 
       FIG. 4B  shows a cross-sectional view of one side of each loop of a charging coil  400  in accordance with section line D-D and how the diameter of the wire gradually increases over most of the length of the wire so that the wire diameter gets progressively larger between adjacent loops. While a gradually increasing wire diameter is depicted it should be appreciated that the wire diameter can both increase and decrease. For example, where an associated device housing has a protrusion coinciding with portion  404  of charging coil  400 , then the diameter of portion  404  could be substantially greater than that of portions  404  and  408 . Other variations include the diameter of the charging coil changing more abruptly. For example, each wire could be configured to reduce rapidly in diameter just prior to crossing beneath lead  402 . 
       FIG. 4C  depicts an alternative embodiment in which each loop is formed from multiple wires that gradually get larger and smaller at the same rate in order to increase or decrease the outer diameter of each loop.  FIG. 4D  shows an embodiment in which only select wires of a bundle of wires increase and decrease in diameter, while the rest of the wires stay the same size and/or increase and decrease in size at different rates. 
       FIG. 4E  shows another configuration of charging coil  450  in which a wire has a varying diameter to match the desired height of the space available for the charging coil. This can be accomplished by drawing different portions of the wire through differing diameter apertures or by changing a diameter of an aperture through which the wire is drawn. Charging coil  450  is drawn so that one portion of the coil gets larger and then gets smaller again. As depicted, charging coil  400  includes leads  451  and  452 . In particular, lead  452  can be configured to pass over loops of charging coil  400 . A diameter of either lead  452  and/or the loops it overlaps can be adjusted to accommodate lead  452 . 
       FIG. 4F  shows a cross-sectional view of one side of each loop of charging coil  450  in accordance with section line E-E and how the diameter of the wire gradually increases and then decreases again so that portion  456  is larger than either of adjacent loops represented by portions  454  and  458 . This configuration can be helpful where an associated device housing has a protrusion coinciding with portion  406  of charging coil  450 . 
       FIG. 5  shows a top view of a charging coil in which different length wires can be joined together and overlap one another so that a central portion of the charging coil is substantially thicker than a peripheral portion of the charging coil. This accomplished by only joining the shorter lengths of wire to the central portion of charging coil  500  by bypassing the outer loops of the charging coil, when the outer loops occupy portions of an associated device housing with minimal space for the charging coil. For example, wire  502  bypasses the first and second loops and is only joined to the inner-most loop of charging coil  500 . In this way, this wire can be coupled with both positive terminal  504  and negative terminal  506  without unduly thickening peripheral portions of charging coil  500 . It should be noted that in some embodiments, terminals  504  and  506  can be dipped in tin so that wires at each end can be kept from fraying or separating and so that each end can be more easily coupled to a single electrical terminal. 
       FIGS. 6A-6D  show perspective views of additional wire configurations.  FIG. 6A  shows a group  600   a  of five constant diameter wires. Wire  602  is substantially shorter than the other wires in the group and terminates before the other wires. As shown in  FIG. 6A , solder  603  electrically couples the end of wire  602  to one or more of the other wires in group  600   a  adjacent to wire  602 . In some embodiments, solder  603  can be a tin solder. In this way, by removing one wire the overall diameter of the remaining wires can be reduced.  FIG. 6B  shows a variable diameter wire  600   b  having a variable diameter that changes gradually over a fixed distance  604 . In some embodiments, the rate of change of the diameter can be constant until a desired diameter is achieved, while in other embodiments the rate of change of the diameter can gradually increase or decrease.  FIG. 6C  shows a variable diameter wire  600   c , which transitions abruptly from diameter  606  to diameter  608 . It should be understood that while the wires are only depicted changing diameter once that the diameter can also change multiple times. Furthermore, variable diameter wires can be grouped together, changing at the same rate or different rates than adjacent wires.  FIG. 6D  shows how in some configurations wires, such as wires  610  in wire bundle  600   d , can have different shapes such as rectangular or trapezoidal to better accommodate interior features of a device housing. 
       FIG. 7  shows a flow chart depicting a method of forming a variable diameter wire used in a charging coil. At  702 , a wire is formed using a wire drawing operation. This type of operation can be conducted by starting with a coil of hot rolled wire and then fed through a wire drawing machine. The wire is pulled through an aperture defined by a die that is smaller than the diameter of the wire, resulting in a lengthening and thinning of the wire stock. In some embodiments, multiple dies can be arranged in series having successively smaller apertures that eventually achieve a desired diameter of the wire. Alternatively, portions of the wire can selectively plated with electrically conductive materials to increase particular portions of the wire. In certain cases, a diameter of the wires can be reduced by chemically etching portions of the wire away. In some embodiments, these additive and subtractive processes can be used to adjust the charging coil to conform to various asymmetric device housing features proximate the charging coil At  704 , different diameters can be applied to various different portions of the wire. The size of one or more of the dies can be adjusted to vary the diameter of the wire during the drawing operation. Alternatively, only a portion of the wire can be drawn through a particular die so that the portion drawn through the die can be substantially smaller than the portion not drawn through the die. At  706 , the drawn wire or wires can be arranged into multiple loops so that a portion of the wires with larger diameters are arranged in areas of a device housing with larger amounts of space and portions of the wires with smaller diameters are arranged in areas of the device housing with less space. 
     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: 20160516
Publication Date: 20191203
Grant Date: 20191203
Priority Date: 20160516
Inventors: BUSHNELL, TYLER S.
BRZEZINSKI, MAKIKO K.
GRAHAM, Christopher S.
YAO, Stephen E.
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J50/005", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01F27/2871", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F27/306", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0042", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/2871", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F27/2823", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/2823", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/306", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0042", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F27/2823", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 60295443