PATENT DOCUMENT

Publication Number: US-12095279-B2
Application Number: US-202318512864-A
Country: US
Kind Code: B2

Title: Soft magnetic ring for wireless power devices

Abstract:
A device or an accessory may include a near-field communications antenna and a soft magnetic ring concentric with the near-field communications antenna. The device or accessory may further include at least one wireless power transfer coil concentric with the near-field communications antenna, a rectifier coupled to the at least one wireless power transfer coil, and a battery configured to receive a rectified voltage from the rectifier. The soft magnetic ring may be used to shunt magnetic flux from one or more nearby magnets in external electronic devices to prevent the magnets from repelling each other. The soft magnetic ring may be attracted to a magnet in an external device to help align wireless power transfer coils in the two mated devices.

Claims:
What is claimed is: 
     
       1. An electronic device operable with an external device having a magnet, comprising:
 a wireless power transfer coil; 
 a rectifier coupled to the wireless power transfer coil; 
 a battery coupled to the rectifier; and 
 a soft magnetic ring concentric with the wireless power transfer coil, wherein the soft magnetic ring shunts magnetic flux from the magnet in the external device when the external device is mated with the electronic device. 
 
     
     
       2. The electronic device of  claim 1 , further comprising:
 a near-field communications antenna concentric with the wireless power transfer coil. 
 
     
     
       3. The electronic device of  claim 1 , wherein:
 the external device has an additional wireless power transfer coil; and 
 the soft magnetic ring is attracted to the magnet in the external device to align the wireless power transfer coil and the additional wireless power transfer coil when the external device is mated with the electronic device. 
 
     
     
       4. The electronic device of  claim 1 , wherein the soft magnetic ring shunts magnetic flux from an additional magnet in an additional external device while the external device is mated at a first surface of the electronic device and while the additional external device is mated at a second surface of the electronic device opposing the first surface to prevent the magnet from repelling the additional magnet. 
     
     
       5. The electronic device of  claim 4 , wherein:
 the external device has a front face with a display and a rear face opposing its front face; 
 the rear face of the external device is mated with the first surface of the electronic device; 
 the additional external device has a front face with a display and a rear face opposing its front face; and 
 the rear face of the additional external device is mated with the second surface of the electronic device. 
 
     
     
       6. The electronic device of  claim 5 , wherein:
 during a first wireless charging mode, the wireless power transfer coil is configured to convey wireless power from the external device to the additional external device; and 
 during a second wireless charging mode, the wireless power transfer coil is configured to convey wireless power from the additional external device to the external device. 
 
     
     
       7. The electronic device of  claim 1 , wherein the soft magnetic ring neither repels nor attracts an additional soft magnetic ring in an additional external device when the additional external device is mated with the electronic device. 
     
     
       8. The electronic device of  claim 1 , wherein the soft magnetic ring is formed from a material having a relative permeability of at least 1000. 
     
     
       9. The electronic device of  claim 1 , wherein the soft magnetic ring is formed from a soft magnetic material selected from the group consisting of: iron, nickel, cobalt, steel, ferrite, steel, nanocrystalline material, mu-metal, and permalloy. 
     
     
       10. The electronic device of  claim 1 , wherein the soft magnetic ring is formed from a material having a saturation flux density of at least 0.5 Tesla. 
     
     
       11. An accessory operable with an electronic device, comprising:
 a housing having a face configured to receive the electronic device having a magnet; and 
 a soft magnetic ring configured to shunt magnetic flux from the magnet when the electronic device is received at the face of the housing. 
 
     
     
       12. The accessory of  claim 11 , further comprising:
 an annular near-field communications antenna disposed adjacent to the soft magnetic ring. 
 
     
     
       13. The accessory of  claim 11 , further comprising:
 at least one wireless power transfer coil concentric with the soft magnetic ring and configured to transmit or receive wireless power from an additional wireless power transfer coil in the electronic device; 
 a rectifier coupled to the wireless power transfer coil; and 
 a load configured to receive a rectified voltage from the rectifier. 
 
     
     
       14. The accessory of  claim 11 , wherein the soft magnetic ring is formed from a material having a relative permeability of at least 1000. 
     
     
       15. The accessory of  claim 11 , wherein the soft magnetic ring is formed from a soft magnetic material selected from the group consisting of: iron, nickel, cobalt, steel, ferrite, steel, nanocrystalline material, mu-metal, and permalloy. 
     
     
       16. A system comprising:
 an electronic device having a magnet, a wireless power transfer coil, and a battery; and 
 an accessory operable to mate with the electronic device, wherein the accessory includes a soft magnetic ring configured to shunt magnetic flux from the magnet when the electronic device is mated with the accessory. 
 
     
     
       17. The system of  claim 16 , further comprising:
 a power transmitting device operable to mate with the electronic device or the accessory, wherein the power transmitting device comprises an additional magnet, and wherein the soft magnetic ring is configured to shunt magnetic flux from the additional magnet when the power transmitting device is mated with the accessory. 
 
     
     
       18. The system of  claim 16 , wherein the electronic device further comprises a soft magnetic ring concentric with the wireless power transfer coil. 
     
     
       19. The system of  claim 18 , further comprising:
 an additional electronic device operable to mate with the electronic device, wherein the additional electronic device includes a magnet, a wireless power transfer coil, a battery, and a soft magnetic ring, and wherein wireless power is conveyed between the electronic device and the additional electronic device when the additional electronic device is mated with the electronic device. 
 
     
     
       20. The system of  claim 16 , wherein:
 the electronic device further comprises a near-field communications antenna concentric with the wireless power transfer coil; and 
 the accessory comprises a near-field communications antenna concentric with the soft magnetic ring.

Description:
This application is a continuation of patent application Ser. No. 17/380,957, filed Jul. 20, 2021, which claims the benefit of provisional patent application No. 63/211,700, filed Jun. 17, 2021, which are hereby incorporated by reference herein in their entireties. 
    
    
     FIELD 
     This relates generally to power systems, and, more particularly, to wireless power systems for charging electronic devices. 
     BACKGROUND 
     In a wireless charging system, a wireless power transmitting device wirelessly transmits power to a wireless power receiving device. Magnets may be used to align the wireless power transmitting device and wireless power receiving device with each other. 
     During operation, the wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device. The wireless power receiving device has a coil and rectifier circuitry. The coil of the wireless power receiving device receives alternating-current wireless power signals from the wireless power transmitting device. The rectifier circuitry converts the received signals into direct-current power. 
     SUMMARY 
     Power may be transmitted wirelessly between electronic devices. Devices such as cellular telephones, wireless charging pucks, battery cases, and other equipment may have wireless power coils. The coils in devices that transmit and receive power can be aligned magnetically. Proper operation may be ensured by aligning the coil in a device that is wirelessly transmitting power to an overlapping coil in a device that is wirelessly receiving power. To magnetically align and attach first and second devices for power transfer between their coils, the first and second devices may be provided with respective mating alignment magnets. The alignment magnets may be arranged in patterns such as rings. 
     In accordance with some embodiments, a device having a soft magnetic ring may be interposed between two external devices of the same type or model. The external devices may each have an alignment magnet. A first external device has a rear face that mates with a first face of the device. A second external device has a rear face that mates with a second face of the device. Mated in this way, the soft magnetic ring in the device shunts magnetic flux from the magnet in the first external device while shunting magnetic flux from the magnet in the second external device to prevent the two magnets from repelling one another. The device may further include at least one wireless charging coil concentric with the soft magnetic ring and a near-field communications antenna concentric with the soft magnetic ring. The device may be a battery case, a removable case, or other accessory. 
     In accordance with some embodiments, a device such as a cellular telephone may be provided with a soft magnetic ring. The device may further include a wireless charging coil concentric with the soft magnetic ring and a near-field communications antenna concentric with the soft magnetic ring. Such device may be directly mated with another device of the same type or model without the soft magnetic rings repelling each other. Such device may also be compatible with a wireless charging puck having a magnet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of an illustrative wireless power system in accordance with some embodiments. 
         FIG.  2    is a schematic diagram of illustrative wireless power circuitry in a pair of mated electronic devices in accordance with some embodiments. 
         FIG.  3    is a perspective view of illustrative first and second electronic devices in a back-to-back configuration for wireless power transfer in accordance with some embodiments. 
         FIGS.  4 A,  4 B,  5 A, and  5 B  are schematic diagrams of illustrative alignment magnet arrangements. 
         FIG.  6 A  is a cross-sectional side view of illustrative first and second electronic devices in a back-to-back configuration for wireless power transfer through an accessory having a soft magnetic ring in accordance with some embodiments. 
         FIG.  6 B  shows how the soft magnetic ring in the accessory of  FIG.  6 A  is used to shunt magnetic flux from magnets within the first and second electronic devices in accordance with some embodiments. 
         FIG.  6 C  is a top (plan) view of an illustrative electronic device having a wireless charging coil, a near-field communications (NFC) antenna, and a soft magnetic ring in accordance with some embodiments. 
         FIG.  7    is a cross-sectional side view of an illustrative accessory having a soft magnetic ring in accordance with some embodiments. 
         FIG.  8    is a cross-sectional side view of an illustrative accessory having a soft magnetic ring interposed between an electronic device and a wireless charging puck in accordance with some embodiments. 
         FIG.  9    is a cross-sectional side view of illustrative first and second electronic devices each having a soft magnetic ring and operated in a back-to-back configuration for wireless power transfer in accordance with some embodiments. 
         FIG.  10 A  is a cross-sectional side view of an illustrative electronic device having a soft magnetic ring mounted on a wireless charging puck in accordance with some embodiments. 
         FIG.  10 B  shows how the soft magnetic ring within the electronic device of  FIG.  10 A  is used to shunt magnetic flux from magnets within the wireless charging puck in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     A wireless power system includes electronic devices such as wrist watches, cellular telephones, tablet computers, laptop computers, removable cases, electronic device accessories, wireless charging mats, wireless charging pucks, and/or other electronic equipment. These electronic devices have wireless power circuitry. For example, an electronic device may have a wireless power coil. Some devices use wireless power coils for transmitting wireless power signals. Other devices use wireless power coils for receiving transmitted wireless power signals. If desired, some of the devices in a wireless power system may have both the ability to transmit wireless signals and to receive wireless signals. A cellular telephone or other portable electronic device may, as an example, have a coil that can be used to receive wireless power signals from a charging puck or other wireless transmitting device and that can also be used to transmit wireless power to another wireless power device (e.g., another cellular telephone). A device with one or more wireless power coils that is used for transmitting and/or receiving wireless power signals may be referred to as a wireless power device. Devices with power transmitting capabilities may sometimes be referred to as wireless power transmitting devices or wireless power devices. Devices with power receiving capabilities may sometimes be referred to as wireless power receiving devices or wireless power devices. 
     A wireless power system containing two or more wireless power devices is shown in  FIG.  1   . As shown in  FIG.  1   , wireless power system  8  may include wireless power devices  10 . Each wireless power device in system  8  may include a housing containing one or more components such as power source  12 , control circuitry  14 , wireless power circuitry  16 , input-output devices  18 , and alignment magnets  20 . The housing may be formed from polymer, metal, glass, ceramic, other materials, and/or combinations of these materials. 
     Power source  12  may include an alternating-current-to-direct-current power adapter that converts wall power (mains power) from an alternating-current source to direct-current power to power the circuitry of device  10  and/or may include a source of direct-current power such as a battery. If desired, devices with batteries can be wirelessly charged by receiving wireless power signals from a wireless power transmitting device. 
     Control circuitry  14  in each device  10  of system  8  is used in controlling the operation of system  8 . This control circuitry may include processing circuitry associated with microprocessors, power management units, baseband processors, digital signal processors, microcontrollers, system(s) on chips (SoCs), and/or application-specific integrated circuits with processing circuits. The processing circuitry implements desired control and communications features in devices  10 . For example, the processing circuitry may be used in processing user input, handling negotiations between devices  10 , sending and receiving in-band and out-of-band data, making measurements, estimating power losses, determining power transmission levels, and otherwise controlling the operation of system  8 . 
     Control circuitry  14  in system  8  may be configured to perform operations in system  8  using hardware (e.g., dedicated hardware or circuitry), firmware and/or software. Software code for performing operations in system  8  and other data is stored on non-transitory computer readable storage media (e.g., tangible computer readable storage media) in control circuitry  8 . The software code may sometimes be referred to as software, data, program instructions, instructions, or code. The non-transitory computer readable storage media may include non-volatile memory such as non-volatile random-access memory (NVRAM), one or more hard drives (e.g., magnetic drives or solid state drives), one or more removable flash drives or other removable media, or the like. Software stored on the non-transitory computer readable storage media may be executed on the processing circuitry of control circuitry  14 . The processing circuitry may include application-specific integrated circuits with processing circuitry, one or more microprocessors, a central processing unit (CPU) or other processing circuitry. 
     Devices  10  use wireless power circuitry  16  to transmit and/or receive wireless power signals  22  between devices  10 . Wireless power circuitry  16  of each device  10  may include one or more coils. Configurations in which each device  10  has a single coil may sometimes be described herein as an example. 
     Each device  10  in system  10  may have optional input-output devices  18 . Input-output devices  18  may include input devices for gathering user input and/or making environmental measurements and may include output devices for providing a user with output. As an example, input-output devices  18  may include a display for creating visual output, a speaker for presenting output as audio signals, light-emitting diode status indicator lights and other light-emitting components for emitting light that provides a user with status information and/or other information, haptic devices for generating vibrations and other haptic output, and/or other output devices. 
     Input-output devices  18  may also include sensors for gathering input from a user and/or for making measurements of the surroundings of system  8 . Illustrative sensors that may be included in input-output devices  18  include three-dimensional sensors (e.g., three-dimensional image sensors such as structured light sensors that emit beams of light and that use two-dimensional digital image sensors to gather image data for three-dimensional images from light spots that are produced when a target is illuminated by the beams of light, binocular three-dimensional image sensors that gather three-dimensional images using two or more cameras in a binocular imaging arrangement, three-dimensional lidar (light detection and ranging) sensors, three-dimensional radio-frequency sensors, or other sensors that gather three-dimensional image data), cameras (e.g., infrared and/or visible cameras with respective infrared and/or visible digital image sensors and/or ultraviolet light cameras), gaze tracking sensors (e.g., a gaze tracking system based on an image sensor and, if desired, a light source that emits one or more beams of light that are tracked using the image sensor after reflecting from a user&#39;s eyes), touch sensors, buttons, capacitive proximity sensors, light-based (optical) proximity sensors such as infrared proximity sensors, other proximity sensors, force sensors, sensors such as contact sensors based on switches, gas sensors, pressure sensors, moisture sensors, magnetic sensors, audio sensors (microphones), ambient light sensors, optical sensors for making spectral measurements and other measurements on target objects (e.g., by emitting light and measuring reflected light), microphones for gathering voice commands and other audio input, distance sensors, motion, position, and/or orientation sensors that are configured to gather information on motion, position, and/or orientation (e.g., accelerometers, gyroscopes, compasses, and/or inertial measurement units that include all of these sensors or a subset of one or two of these sensors), sensors such as buttons that detect button press input, joysticks with sensors that detect joystick movement, keyboards, and/or other sensors. Each device  10  may omit some or all of devices  18  or may include one or more of devices  18 . 
     Input-output devices  18  may also include wireless communications circuitry such as radio-frequency (RF) communications circuitry and near-field communications (NFC) circuitry. Data conveyed using these NFC components may be considered out-of-band signals and may be radiated using a separate NFC antenna within each device. NFC circuitry may include circuitry that operates as an NFC reader (sometimes referred to as a proximity coupling device or PCD) and/or as an NFC tag (sometimes referred to as a proximity inductive coupling card or PICC). An NFC tag may be active or passive. An active NFC tag can actively transmit a signal to the NFC reader, whereas a passive NFC tag modulates the carrier waveform transmitted by the NFC reader. Exemplary NFC communications operate at 13.56 MHz. In some embodiments, NFC communications may employ millimeter/centimeter wave technologies at 10 GHz or above (to about 300 GHz). 
     Devices  10  in system  8  have alignment magnets  20  to facilitate magnetic attachment and alignment of a pair of devices  10  to each other. For example, each device  10  may have magnets  20  that help align that device  10  to another device so that the coils in each respective device overlap and are positioned for wireless power transfer. The use of magnets  20  for coil alignment allows power to be transferred satisfactorily between devices  10 . 
     As shown in  FIG.  2   , wireless power circuitry  16  may include wireless power coils  36  coupled to corresponding power and communications circuitry  26 . There may be one or more coils  36  in each device  10 . For example, devices  10  may each include a single coil and/or one or more devices  10  in system  8  may include multiple coils  36 . In arrangements in which devices  10  have more than one coil  36 , coils  36  may be arranged in a two-dimensional array (e.g., a two-dimensional array of overlapping coils that cover a charging surface) and/or may be stacked on top of each other (e.g., to allow wireless signals to be transmitted and/or received on opposing sides of a device). To facilitate transmission of wireless power between a first device and a second device, the coils of the first and second devices may be placed adjacent to each other (e.g., a coil in the first device may overlap and be aligned with a corresponding coil in a second device). 
     Power and communications circuitry  26  may include inverters  28  and rectifiers  30 . Circuitry  26  may also include communications circuitry such as transmitters  32  and receivers  34 . When it is desired to transmit power wirelessly, the inverter  28  in a transmitting device may provide alternating-current signals (currents) to a corresponding coil  36  in the transmitting device. These alternating-current signals may have frequencies of 50 kHz to 1 MHz, 100-250 kHz at least 100 kHz, less than 500 kHz, or other suitable frequency. As alternating-current signals flow through the coil  36  in the transmitting device, alternating-current electromagnetic signals (e.g., magnetic field or magnetic flux signals) are generated and are received by an adjacent coil  36  in a receiving device. This induces alternating-current signals (currents) in the coil  36  of the receiving device that are rectified into direct-current power by a corresponding rectifier  30  in the receiving device. Rectifier  30  can provide the direct-current power to a load (e.g., a battery) or other electronic components within device  10 . In arrangements in which devices  10  have both inverters and rectifiers, bidirectional power transfer is possible. Each device can transmit power using its inverter  28  or may receive power using its rectifier  30 . 
     Transmitters  32  and receivers  34  may be used for wireless communications. In some embodiments, out-of-band communications (e.g., Bluetooth® communications and/or other wireless communications using radio-frequency antennas in one or more radio-frequency communications bands may be supported). In other embodiments, coils  36  may be used to transmit and/or receive in-band communications data. Any suitable modulation scheme may be used to support in-band communications, including analog modulation, frequency-shift keying (FSK), amplitude-shift keying (ASK), and/or phase-shift keying (PSK). In an illustrative embodiment, FSK communications and ASK communications are used in transmitting in-band communications traffic between devices  10  in system  8 . A wireless power transmitting device may, as an example, use its transmitter  32  to impose frequency shifts onto the alternating-current signals being supplied by its inverter  28  to its coil  36  during wireless power transfer operations and a wireless power receiving device may use its coil  36  and its receiver  34  to receive these FSK signals. The receiving device in this scenario may use its transmitter  32  to modulate the impedance of its coil  36 , thereby creating corresponding changes in the current flowing through the wireless power transmitting device coil that are detected and demodulated using the receiver  34  in the wireless power transmitting device. In this way, the transmitter  32  in the wireless power receiving device can use ASK communications to transmit in-band data to the receiver  34  in the wireless power transmitting device while wireless power is being conveyed from the wireless power transmitting device to the wireless power receiving device. In some embodiments, some devices  10  have both transmitters  32  and receivers  34  and other devices  10  have only transmitters  32  or have only receivers  34 . 
     It is desirable for devices  10  to be able to communicate information such as received power, battery states of charge, power measurements, and so forth, to control wireless power transfer. The present technology contemplates avoidance of the transmission of personally identifiable information in order to provide wireless power transfer functions. Out of an abundance of caution, it is noted that to the extent that any implementation of this charging technology involves the use of personally identifiable information, for example during authentication, that implementers should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     To ensure satisfactory wireless power transfer and in-band communications, devices  10  may have alignment magnets  20 . The housings of devices  10  may be formed from metal, polymer, glass, and/or other materials through which direct-current magnetic fields from permanent magnets such as alignment magnets  20  may pass. Alignment magnets  20  can be used to help ensure alignment between coils  36  in paired (mated) devices. Magnets  20  may have ring shapes, or other suitable shapes, and may each include one more permanent magnet elements with magnetic pole pairs in locations that facilitate alignment and attachment of devices  10  to each other. As an example, magnets  20  may be configured so that when the magnet  20  in a first device is magnetically attached to a corresponding magnet  20  in a second device, coil  36  of the first device will be overlapped by and aligned with coil  36  of the second device. 
     It may sometimes be desired to transfer power between two devices of the same type (e.g., first and second cellular telephones of the same model). Each device may have a coil mounted within the housing of the device. The coil may be mounted adjacent to the rear wall (back wall) of the housing and may be configured to transmit and receive wireless signals through the rear wall. The rear wall may, in an illustrative arrangement, be formed from a dielectric such as glass or polymer. When it is desired to transfer power between first and second devices, the second device may be placed on top of the first device in a back-to-back arrangement of the type shown in  FIG.  3   . As shown in the example of  FIG.  3   , first electronic device  10 A has a front face (front) FA and an opposing rear face (rear or back) RA. Second electronic device  10 B, which is resting on top of first device  10 A in the orientation of  FIG.  2   , has a front face (front) FB and has an opposing rear face (rear or back) RB. Devices  10 A and  10 B each has a display at its front face. When placed back-to-back to align the respective coils of devices  10 A and  10 B, rear faces RA and RB face each other as shown in  FIG.  3   . Rear faces RA and RB may, for example, contact each other when devices  10 A and  10 B are mated. 
       FIG.  4 A  is a top (front) view of electronic device alignment magnet  20  viewed from the front face of a device. As shown in  FIG.  4 A , magnet  20  has one or more permanent magnet elements  20 C whose magnetic pole pairs are oriented in the X-Y plane such that magnetic poles common to each element are located in concentric inner and outer ring areas with opposite magnetic poles, where the inner ring area IR has a first magnetic polarity (south in the example of  FIG.  4 A ) and the outer ring area OR has a second magnetic polarity (north in the example of  FIG.  4 A ). The designations of N (to represent north poles) and S (to represent south poles) in  FIGS.  4 A and  4 B  and the other drawings are illustrative. It will be appreciated that throughout this description these designations can be reversed with no loss of generality (e.g., in any given embodiment S can be swapped for N and vice versa). This alignment magnet polarity pattern allows a device containing magnet  20  to magnetically attach to another device having a corresponding ring-shaped alignment magnet  20 ′ with poles of opposite polarity (see, e.g., magnet  20 ′ of  FIG.  5 A , in which inner and outer sets of vertical magnets are arranged in concentric circles so that inner ring area IR has an exposed pole of north polarity and outer ring area OR has an exposed pole of south polarity). Magnet  20  configured in this way is sometimes referred to as a ring-shaped magnet array. 
       FIG.  4 B  is a cross-sectional side view of magnet  20  of  FIG.  4 A  taken along line  42  of  FIG.  4 A  and viewed in direction  44 . As shown in  FIG.  4 B , magnets  20  produce a magnetic flux that is illustrated by magnetic field lines  45  originating from the north (N) pole to the south (S) pole. Magnetic field lines  45  emanating from the north pole may bend upward (or downward) in the Z direction and extend radially towards the center  40  of magnet  20  before bending downward (or upward) to terminate at the south pole. 
       FIG.  5 A  is a top (front) view of an alignment magnet  20 ′ in a wireless charging puck. As shown in  FIG.  5 A , magnet  20 ′ has concentric inner and outer magnet ring areas with opposite magnetic poles, where the inner ring area IR has a first magnetic polarity (north in the example of  FIG.  5 A ) and the outer ring area OR has a second magnetic polarity (south in the example of  FIG.  5 A ). This alignment magnet polarity pattern allows a device containing magnet  20 ′ to magnetically attach to another device having a corresponding ring-shaped alignment magnet  20  of the type shown in  FIGS.  4 A and  4 B . 
       FIG.  5 B  is a cross-sectional side view of magnets  20 ′ of  FIG.  5 A  taken along line  46  of  FIG.  5 A  and viewed in direction  48 . As shown in  FIG.  5 B , magnet  20 ′ of the charging puck may have one or more permanent magnet elements  20 C that each consist of two vertically oriented (i.e. in the z-axis) magnet pole pairs that may exist in one homogeneous material or as two separate materials mounted together, each pole pair having a first pole stacked vertically (in the z-axis) on top of a second opposite pole such that the poles located at the uppermost surface in the z-axis (i.e. most positive z-axis value) are common to each permanent magnet element and determine the polarity of the corresponding outer ring area OR and inner ring area IR. The two vertically oriented magnet pole pairs in each magnet element  20 C can be separated by a non-magnetized zone  51 . This causes magnetic flux from magnets  20 ′ to be oriented vertically at the uppermost surface in the z-axis (i.e. most positive z-axis value). Ferrite  50  helps confine magnetic flux at the bottoms of magnets  20 ′ and may be composed of any magnetically soft material such as iron or an alloy of iron. 
     Although the arrangement of  FIGS.  4 A,  4 B,  5 A, and  5 B  allows an electronic device having magnet  20  to mate with a charging puck having magnet  20 ′, first and second electronic devices with magnets  20  of the type shown in  FIGS.  4 A and  4 B  cannot mate with each other, because when the first and second electronic devices are placed back to back in an attempt to align magnets  20 , the outer ring area OR consisting of north poles of the first electronic device will repel the corresponding outer ring area OR of north poles of the second electronic device. The south poles of the first and second devices will also repel each other when overlapping. As a result, two devices having identical magnets  20  may not be properly aligned for wireless charging between peer devices. 
     Turning to  FIG.  6 A , devices  10  of system  8  may overcome this challenge by inserting a device with a soft magnetic ring between two devices having magnets  20  that would otherwise repel each other when placed in the back-to-back configuration. As shown in  FIG.  6 A , a first electronic device  10 A may be oriented face down, a second electronic device  10 B (i.e., an electronic device of the same type or model as device  10 A) may be oriented face up, and a third device  10 C may be interposed between devices  10 A and  10 B oriented in a back-to-back configuration. Devices  10 A and  10 B may each include a wireless power coil  36  (sometimes referred to as a wireless charging coil), a near-field communications (NFC) antenna  60  surrounding the wireless charging coil  36 , and magnet  20  (see, e.g., magnet  20  of the type shown in  FIGS.  4 A and  4 B ) surrounding the near-field communications antenna  60 . Coil  36 , NFC antenna  60 , and magnet  20  may be concentric annular (ring-like) structures. NFC antenna  60  may be used to transmit and/or receive out-of-band information between devices  10 . 
     The example of  FIG.  6 A  in which NFC antenna  60  is disposed between coil  36  and magnet  20  within devices  10 A and  10 B is merely illustrative. As another example, the position of magnet  20  and NFC antenna  60  can be swapped such that magnet  20  is interposed between coil  36  and antenna  60 . As another example, the position of coil  36  and NFC antenna  60  can be swapped such that coil  36  is interposed between antenna  60  and magnet  20 . As another example, coil  36  may surround magnet  20  while the NFC antenna  60  surrounds coil  36  such that magnet  20  runs along an inner peripheral edge of coil  36 . As another example, the position of coil  36  and magnet  20  can be swapped such that coil  36  runs along an outer peripheral edge of NFC antenna  60 . As yet another example, magnet  20  may surround NFC antenna  60  while coil  36  surrounds magnet  20  such that magnet  20  is interposed between an outer peripheral edge of NFC antenna  60  and an inner peripheral edge of coil  36 . If desired, other non-concentric arrangements can also be used. 
     Device  10 C may be a removable battery case (sometimes referred to as an external accessory or accessory device). Device  10 C has a housing with a recess R and/or other structures configured to receive device  10 B. In this way, a user may removably attach device  10 B to device  10 C so that devices  10 B and  10 C may be used together as a portable unit. Device  10 C may provide supplemental power to device  10 B while protecting device  10 B from damage due to stress-producing events such as drop events when device  10 B is installed on device  10 C. This example in which device  10 C has a protruding lip portion  68  shaped to receive the rear face of device  10 B is merely illustrative. In other embodiments, device  10 C may lack protruding portion  68  and may magnetically attach to device  10 B using soft magnetic ring  70 . 
     Device  10 C may include two wireless power coils such as coils  62  and  64 . During a bypass mode of operation, coils  62  and  64  are shorted together. Electrical components such as battery  66  may be interposed between coils  62  and  64 . The shorting of coils  62  and  64  allows internal device components such as battery  18  to be effectively bypassed when wireless power is being conveyed between devices  10 A and  10 B. Devices  10 A and  10 B may transmit power and/or may receive wireless power (e.g., devices  10 A and  10 B may support bidirectional charging when placed in the back-to-back configuration). As an example, during a first wireless charging mode when device  10 A is transmitting wireless power to device  10 B, alternating current electromagnetic signals that are transmitted by coil  36  in device  10 A are received by coil  62 . Since coil  64  is shorted to coil  62  in this mode of operation, coil  64  emits electromagnetic signals that are received by coil  36  in device  10 B. As another example, during a second wireless charging mode when device  10 B is transmitting wireless power to device  10 A, alternating current electromagnetic signals that are transmitted by coil  36  in device  10 B are received by coil  64 . Since coil  64  is shorted to coil  62  in this mode of operation, coil  62  emits electromagnetic signals that are received by coil  36  in device  10 A. 
     Device  10 C may include a near-field communications (NFC) antenna  60  surrounding coils  62  and  64 . NFC antenna  60  may be used to convey information about device  10 C to device  10 B and/or device  10 A. For example, antenna  60  may be configured to convey a device type (e.g., whether device  10 C is a removable case or a wireless charging puck, etc.), a physical characteristic of the device such as the actual color of the device, a function of the device, or other information associated with that device. 
     In accordance with an embodiment, device  10 C may further include a ring of soft magnetic material (see, e.g., ring  70 ) surrounding NFC antenna  60 . Ring  70  may be formed from “soft” magnetic material(s), which are defined as magnetic materials that are easily magnetized and demagnetized. Unlike “hard” (permanent) magnets, which retain their magnetism and have poles that can attract opposite polarities and repel like polarities, soft magnetic materials only become magnetized (i.e. have a magnetic flux) when an external magnetic field is applied but do not retain their magnetism when the external magnetic field is removed. Ring  70  (sometimes referred to as a soft magnetic ring or a ring-like soft magnetic structure) is not a permanent magnet per se and does not have static poles, so it will not repel other magnets. 
     Soft magnetic materials are characterized by a high relative permeability (e.g., a relative permeability of at least 500, 500-1000, at least 1000, at least 10,000 or at least 100,000 or more), which measures how readily a material conducts magnetic flux due to an applied magnetic field. Ring  70  should also be formed from soft magnetic material with sufficient saturation flux density (e.g., a saturation flux density of at least 0.5 T, 0.5-1 T, 1-2 T, or more than 2 T), which measures the point at which the magnetic material cannot contain any more magnetic flux. 
     As examples, ring  70  may be formed from soft magnetic materials such as soft ferromagnetic (iron-based metal alloy) and/or soft ferrimagnetic (iron-based ceramic) materials, which may include pure iron annealed in hydrogen (which has a relative permeability of 200,000 and a saturation flux density of 2 T), pure iron without annealing (which has a relative permeability of 5,000 and a saturation flux density of 2.2 T), nickel (which has a relative permeability of 100-600 and a saturation flux density that is greater than ceramic ferrites), cobalt (which has a relative permeability of 18,000 and a saturation flux density of 1.2-1.8 T), nickel-plated steel, soft ferrite, steel, silicon steel (e.g., an iron alloy with 3-4% silicon), low carbon steel (e.g., an iron alloy with 0.2-0.4% carbon with a relatively permeability of 1000-3000 and a saturation density of 2.2 T), soft nanocrystalline ferrite material (which has a relative permeability of 10,000-100,000 or more and a saturation flux density of 1-2 T), Mu-metal ferromagnetic alloy (which has a relative permeability of 300,000-400,000 and a saturation flux density of 0.8-1.6 T), permalloy ferromagnetic alloy (which has a relative permeability of 10,000-100,000 or more and a saturation flux density of 0.6-1.2 T), some combination of these materials, and/or other suitable soft magnetic material with high relatively permeability and high saturation flux density. 
     Ring  70  formed using soft magnetic material(s) with high relative permeability and high saturation flux density enables ring  70  to block and short out (shunt) magnetic flux emanating from nearby magnets while providing magnetic/mechanical attraction forces between ring  70  and the nearby magnets.  FIG.  6 B  is a cross-sectional side view showing how soft magnetic ring  70  in device  10 C is used to shunt magnetic flux from magnets  20  within electronic devices  10 A and  10 B when placed in the back-to-back configuration. Operated in this way, the wireless charging coil in device  10 A will be properly aligned with the wireless charging coil in device  10 B. Soft magnetic ring  70  may therefore sometimes be referred to as a magnetic flux shunting (shorting) structure or a magnetic field shunting (shorting) structure. 
     As shown in  FIG.  6 B , magnetic fields  72  from magnet  20  in device  10 A will be shorted (shunted) by soft magnetic ring  70  (e.g., magnetic field line  72  originating from the north pole of magnet  20  travels upward towards an outer peripheral edge of ring  70 , travels along the width of ring  70  towards the center of the device before exiting an inner peripheral edge of ring  70 , and then travels downward towards the south pole of magnet  20 ). Similarly, magnetic fields  72 ′ from magnet  20  in device  10 B will also be shorted (shunted) by soft magnetic ring  70  (e.g., magnetic field line  72 ′ originating from the north pole of magnet  20  travels downward towards an outer peripheral edge of ring  70 , travels along the width of ring  70  towards the center of the device before exiting an inner peripheral edge of ring  70 , and then travels upwards toward the south pole of magnet  20 ). If ring  70  had not been interposed between magnets  20 , the magnetic field  72 A emanating from magnet  20  in device  10 A would repel the magnetic field  72 B emanating from magnet  20  in device  10 B, which would cause devices  10 A and  10 B to be misaligned. Ring  70  has a thickness T. Ring  70  that is thicker can hold more magnetic flux and is thus better at shielding and shunting magnetic fields from nearby magnets. Thickness T may, for example, be at least 0.5 mm, less than 0.5 mm, 0.5-1 mm, or greater than 1 mm. 
       FIG.  6 C  is a top (front) view showing wireless charging coil  64 , NFC antenna  60 , and soft magnetic ring  70  in an illustrative device  10 C. Coil  64  may be ring-shaped (sometimes referred to as an annular coil or circular coil) and may have a central opening with one or more magnetic cores optionally formed in the central opening. Ring-shaped NFC antenna  60  may laterally surround coil  64 . NFC antenna  60  may sometimes be described as annular or circular. Soft magnetic ring  70  may laterally surround NFC antenna  60 . Ring  70  may also sometimes be described as annular or circular. In  FIG.  6 C , coil  64 , antenna  60 , and soft magnetic ring  70  are concentric (e.g., each structure  64 ,  60 , and  70  has a center coinciding at point C). Antenna  60  runs along a peripheral (outer) edge of wireless charging coil  64 . Ring  70  runs along a peripheral (outer) edge of NFC antenna  60 . Ring  70  may have a width W that is similar to the width of magnets  20  within devices  10 A and  10 B. 
     The example of  FIG.  6 C  in which NFC antenna  60  is disposed between coil  64  and ring  70  within device  10 C is merely illustrative. As another example, the position of ring  70  and NFC antenna  60  can be swapped such that ring  70  is interposed between coil  64  and antenna  60 . As another example, the position of coil  64  and NFC antenna  60  can be swapped such that coil  64  is interposed between antenna  60  and ring  70 . As another example, coil  64  may surround ring  70  while the NFC antenna  60  surrounds coil  64  such that ring  70  runs along an inner peripheral edge of coil  64 . As another example, the position of coil  36  and magnet  20  can be swapped such that coil  36  runs along an outer peripheral edge of NFC antenna  60 . As yet another example, ring  70  may surround NFC antenna  60  while coil  64  surrounds ring  70  such that ring  70  is interposed between an outer peripheral edge of NFC antenna  60  and an inner peripheral edge of coil  64 . If desired, other non-concentric arrangements can also be used. In other suitable embodiments, the wireless charging coil, NFC antenna structure, and the soft magnetic flux shunting ring structure may be oval, triangular, rectangular, pentagonal, hexagonal, octagonal, or have another polygonal footprint. 
     The example of  FIGS.  6 A- 6 C  in which a removable battery case  10 B is interposed between devices  10 A and  10 B to prevent magnets  20  from repelling one another is merely illustrative. In accordance with another embodiment, a device such as accessory  10 D can also include a soft magnetic ring  70  surrounding an NFC antenna  60 . Accessory  10 D may be a removable case that does not include any wireless charging coil or battery. Device  10 D has a housing with a recess R and/or other structures configured to receive an electronic device  10 . A user may removably attach a device  10  to accessory  10 D so that devices  10  and  10 D are used together as a portable unit. This example in which device  10 D has a protruding lip portion  69  shaped to receive the rear face of a device  10  is merely illustrative. In other embodiments, device  10 D may lack protruding portion  69  and may magnetically attach to device  10  using soft magnetic ring  70 . A device  10  that is attached to accessory  10 D having ring  70  can be mated with another device  10  in a back-to-back configuration to perform bidirectional wireless charging operations. 
       FIG.  8    is a cross-sectional side view showing device  10 B attached to an accessory (e.g., accessory  10 C of the type shown in  FIG.  6 A  or accessory  10 D of the type shown in  FIG.  7   ) to form a portable unit, which is placed on device  10 E (e.g., a wireless charging puck or mat). Device  10 B may include magnet  20  of the type described in connection with  FIGS.  4 A and  4 B , which has an outer ring area OR with north polarity and an inner ring area IR with south polarity. Device  10 E may include magnet  20 ′ of the type described in connection with  FIGS.  5 A and  5 B , which has an outer ring area OR with an exposed pole of south polarity and an inner ring area IR with an exposed pole of north polarity. 
     The accessory (e.g., device  10 C or  10 D) stacked between devices  10 B and  10 E includes ring  70  formed using soft magnetic material(s) with high relative permeability and high saturation flux density, which enables ring  70  to block and short out (shunt) magnetic flux emanating from magnets  20  and  20 ′ while providing magnetic/mechanical attraction forces between ring  70  and magnets  20  and  20 ′. As shown in  FIG.  8   , ring  70  in the interposing accessory device is used to shunt magnetic flux from magnet  20  within device  10 B and from magnet  20 ′ within device  10 E. Operated in this way, the wireless charging coil in device  10 B will be properly aligned with the wireless charging coil in device  10 E so that device  10 E can transmit wireless power to device  10 B with optimal efficiency. Soft magnetic ring  70  may therefore sometimes be referred to as a magnetic flux shunting (shorting) structure or a magnetic field shunting (shorting) structure. 
     Magnetic fields  74  from magnet  20  in device  10 B will be shorted (shunted) by soft magnetic ring  70  (e.g., magnetic field line  74  originating from the north pole of magnet  20  travels downward towards an outer peripheral edge of ring  70 , travels along the width of ring  70  towards the center of the accessory before exiting an inner peripheral edge of ring  70 , and then travels upward towards the south pole of magnet  20 ). Similarly, magnetic fields  76  from magnet  20 ′ in device  10 E will also be shorted (shunted) by soft magnetic ring  70  (e.g., magnetic field line  76  originating from the exposed north pole of magnet  20 ′ travels upward towards the inner peripheral edge of ring  70 , travels along the width of ring  70  away from the center of the accessory before exiting the outer peripheral edge of ring  70 , and then travels downwards toward the exposed south pole of magnet  20 ′). 
     The embodiments of  FIG.  6 - 8    in which soft magnetic ring  70  is formed within an accessory that can be interposed between two devices  10  that each include a permanent (hard) magnet is merely illustrative.  FIG.  9    shows another suitable embodiment in which devices  10 A and  10 B (e.g., cellular telephones of the same type or model) each include a soft magnetic ring  70  instead of magnet  20  of the type shown in  FIGS.  4 A and  4 B  and are stacked in a back-to-back configuration. As shown in  FIG.  9   , device  10 A has a rear face RA facing the rear face RB of device  10 B. 
     Similar to ring  70  described in connection with  FIGS.  6 - 8   , rings  70  within devices  10 A and  10 B are formed from soft magnetic materials characterized by a high relative permeability (e.g., a relative permeability of 500 or more, 500-1000, more than 1000, more than 10,000, or more than 100,000) and high saturation flux density (e.g., a saturation flux density of at least 0.5 T, 0.5-1 T, 1-2 T, or more than 2 T). As examples, ring  70  may be formed from soft ferromagnetic and/or soft ferrimagnetic materials, which may include pure iron annealed in hydrogen, pure iron without annealing, nickel, cobalt, nickel-plated steel, soft ferrite, steel, silicon steel (e.g., an iron alloy with 3-4% silicon), low carbon steel (e.g., an iron alloy with 0.2-0.4% carbon, soft nanocrystalline material, mu-metal, permalloy, some combination of these materials, and/or other suitable soft magnetic material with high relatively permeability and high saturation flux density. 
     Since ring  70  of device  10 A and ring  70  of device  10 B are both soft magnetic structures that do not retain any magnetism in the absence of applied magnetic fields from a DC magnet, rings  70  will not repel each other when devices  10 A and  10 B are stacked in the back-to-back configuration. Since rings  70  are demagnetized in this state, there will be no magnetic attraction forces between devices  10 A and  10 B, and the user will need to manually align devices  10 A and  10 B to ensure that the wireless charging coils  36  are aligned for optimal wireless power transfer. 
     Wireless charging coil  36 , NFC antenna  60 , and soft magnetic ring  70  within each of devices  10 A and  10 B may be concentric (annular) structures. The example of  FIG.  9    in which NFC antenna  60  is disposed between coil  36  and ring  70  within devices  10 A and  10 B is merely illustrative. As another example, the position of ring  70  and NFC antenna  60  can be swapped such that ring  70  is interposed between coil  36  and antenna  60 . As another example, the position of coil  36  and NFC antenna  60  can be swapped such that coil  36  is interposed between antenna  60  and ring  70 . As another example, coil  36  may surround ring  70  while the NFC antenna  60  surrounds coil  36  such that ring  70  runs along an inner peripheral edge of coil  36 . As another example, the position of coil  36  and ring  70  can be swapped such that coil  36  runs along an outer peripheral edge of NFC antenna  60 . As yet another example, ring  70  may surround NFC antenna  60  while coil  36  surrounds ring  70  such that ring  70  is interposed between an outer peripheral edge of NFC antenna  60  and an inner peripheral edge of coil  36 . If desired, other non-concentric arrangements can also be used. In other suitable embodiments, coil  36 , NFC antenna  60 , and ring  70  may be oval, triangular, rectangular, pentagonal, hexagonal, octagonal, or have another polygonal footprint. 
     Device  10 B with a soft magnetic ring  70  is compatible with power transmitting devices or even accessories with magnets.  FIG.  10 A  shows device  10 B (e.g., a cellular telephone) with a soft magnetic ring  70  mounted on device  10 E (e.g., a wireless charging puck). As shown in  FIG.  10 A , device  10 B has a rear face RB that is placed on the top charging surface of device  10 E. Device  10 E includes magnet  20 ′ (see, e.g., magnet  20 ′ of the type described in connection with  FIGS.  5 A and  5 B ). When device  10 B is mounted on top of device  10 E, magnet  20 ′ will emit magnetic flux that magnetizes ring  70 . As a result, ring  70  will be magnetically attracted to magnet  20 ′ to align wireless charging coils  36  of devices  10 E and  10 B while power transmitting device  10 E is conveying wireless power to power receiving device  10 B. 
       FIG.  10 B  is a cross-sectional side view showing how soft magnetic ring  70  in device  10 B is used to shunt magnetic flux from magnet  20 ′ within electronic device  10 E when device  10 B is mounted on top of device  10 E. Operated in this way, the wireless charging coil in device  10 B will be properly aligned with the wireless charging coil in device  10 E during wireless charging operations. As shown in  FIG.  10 B , magnetic fields  78  from magnet  20 ′ will be shorted (shunted) by soft magnetic ring  70  (e.g., magnetic field line  78  originating from the exposed north pole of magnet  20 ′ travels upward towards an inner peripheral edge of ring  70 , travels along the width of ring  70  away from the center of device  10 B before exiting an outer peripheral edge of ring  70 , and then travels downward towards the exposed south pole of magnet  20 ′). 
     In general, soft magnetic ring  70  may be incorporated into any device with a wireless charging coil, any device with a battery, or any accessory with or without a battery so that ring  70  can be used to shunt magnetic flux from a nearby magnet while providing magnetic attraction forces to properly aligned two mating devices or accessories. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20231117
Publication Date: 20240917
Grant Date: 20240917
Priority Date: 20210617
Inventors: LOUIS, JEFFREY D.
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J7/00032", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/147", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0048", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/00045", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/34", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/153", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/147", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/0247", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/153", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/147", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/34", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/0247", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/90", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/00045", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J7/0048", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/90", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/00032", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F1/147", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 84489469