PATENT DOCUMENT

Publication Number: US-10714983-B2
Application Number: US-201815902875-A
Country: US
Kind Code: B2

Title: Near-field microwave wireless power system

Abstract:
A wireless power system may use a wireless power transmitting device to transmit wireless power to a wireless power receiving device. The wireless power transmitting device may have microwave antennas that extend along an axis in a staggered arrangement. In the staggered arrangement, the microwave antennas are positioned on alternating sides of the axis. Each microwave antenna is elongated along a dimension that is perpendicular to the axis. Multiple antennas may overlap a wireless power receiving antenna in the wireless power receiving device. Control circuitry may use oscillator and amplifier circuitry to provide antennas that have been overlapped by the wireless power receiving antenna with drive signals. The drive signals may be adjusted based on feedback from the wireless power receiving device to enhance power transmission efficiency. The system may have a wireless power transmitting device with inductive wireless power transmitting coils.

Claims:
What is claimed is: 
     
       1. A wireless power transmitting device configured to transmit wireless power to a wireless power receiving device through a charging surface, comprising:
 a plurality of wireless power transmitting antennas having respective patch antenna resonating elements, wherein the charging surface is characterized by a longitudinal axis and wherein the patch antenna resonating elements are arranged in a staggered configuration along the longitudinal axis; and 
 a transmitter configured to supply alternating-current drive signals to the plurality of wireless power transmitting antennas to transmit the wireless power. 
 
     
     
       2. The wireless power transmitting device of  claim 1  wherein the transmitter comprises an oscillator configured to supply the alternating-current drive signals at a frequency of 500 MHz to 5 GHz. 
     
     
       3. The wireless power transmitting device of  claim 1  wherein the patch antenna resonating elements are rectangular patch antenna resonating elements and wherein the rectangular patch antenna resonating elements have centers alternately located on opposing first and second sides of the longitudinal axis. 
     
     
       4. The wireless power transmitting device of  claim 1  wherein the patch antenna resonating elements are rectangular patch antenna resonating elements and wherein each rectangular patch antenna resonating element is elongated along a dimension perpendicular to the longitudinal axis. 
     
     
       5. The wireless power transmitting device of  claim 1  wherein the patch antenna resonating elements are rectangular patch antenna resonating elements, wherein each rectangular patch antenna resonating element is elongated along a dimension perpendicular to the longitudinal axis, wherein the rectangular patch antenna resonating elements have centers alternately located on opposing first and second sides of the longitudinal axis, and wherein each rectangular patch antenna resonating element has a width and a length that is at least two times the width. 
     
     
       6. The wireless power transmitting device of  claim 1  further comprising inductive wireless charging coils. 
     
     
       7. The wireless power transmitting device of  claim 1  further comprising:
 a plurality of inverters; and 
 a plurality of inductive wireless power transmitting coils each coupled to a respective one of the inverters. 
 
     
     
       8. The wireless power transmitting device of  claim 1  further comprising:
 a plurality of inductive wireless power transmitting coils, each surrounding a respective one of the patch antenna resonating elements. 
 
     
     
       9. The wireless power transmitting device of  claim 1  further comprising inductive wireless charging coils, wherein each of the patch antenna resonating elements lies within a respective one of the inductive wireless charging coils and wherein each of the patch antenna resonating elements includes at least one slot. 
     
     
       10. The wireless power transmitting device of  claim 1  wherein each of the patch antenna resonating elements is configured to transmit wireless power with an efficiency of less than 5% when the wireless power receiving device is not overlapping that patch antenna resonating element and is configured to transmit wireless power with an efficiency of at least 10% when the wireless power device is overlapping that patch antenna resonating element. 
     
     
       11. The wireless power transmitting device of  claim 1  further comprising:
 control circuitry configured to:
 supply a first drive signal to a first of the patch antenna resonating elements and a second drive signal to a second of the patch antenna resonating elements; 
 receive wireless feedback information from the wireless power receiving device; and 
 in response to the wireless feedback information, adjust the first and second drive signals. 
 
 
     
     
       12. The wireless power transmitting device of  claim 11  wherein the first and second drive signals have different phases and wherein the wireless feedback information comprises information on an amount of power wirelessly received at the wireless power receiving device while the wireless power is transmitted by the transmitter. 
     
     
       13. The wireless power transmitting device of  claim 1  further comprising:
 control circuitry configured to adjust phases of drive signals applied respectively to a first of the patch antenna resonating elements and a second of the patch antenna resonating elements based on wirelessly received information from the wireless power receiving device. 
 
     
     
       14. A wireless power transmitting device configured to transmit wireless power to a wireless power receiving device through a charging surface, comprising:
 a row of microwave antennas extending along an axis that runs parallel to the charging surface, wherein each microwave antenna has a corresponding patch antenna resonating element with a center, and wherein the microwave antennas extending along the axis have the centers of their patch antenna resonating elements on alternating sides of the axis; and 
 power transmitting circuitry coupled to the row of microwave antennas. 
 
     
     
       15. The wireless power transmitting device of  claim 14  wherein the power transmitting circuitry is configured to provide a first drive signal to a first of the microwave antennas overlapped by a wireless power receiving antenna element in the wireless power receiving device and is configured to provide a second drive signal of a different phase than the first drive signal to a second of the microwave antennas overlapped by the wireless power receiving antenna element in the wireless power receiving device. 
     
     
       16. The wireless power transmitting device of  claim 14  wherein each of the patch antenna resonating elements has a rectangular shape with a width and a length of at least two times the width that extends along a dimension perpendicular to the axis. 
     
     
       17. The wireless power transmitting device of  claim 14  further comprising:
 an inverter configured to supply an alternating-current signal; and 
 a wireless power transmission coil coupled to the inverter that receives the alternating-current signal and provides corresponding wireless power signals to the wireless power receiving device. 
 
     
     
       18. The wireless power transmitting device of  claim 17  wherein at least one of the patch antenna resonating elements has at least one slot configured to reduce eddy currents when the alternating-current signal is received by the wireless power transmission coil. 
     
     
       19. A wireless power transmitting device configured to transmit wireless power to a wireless power receiving antenna in a wireless power receiving device, comprising:
 a row of patch antenna resonating elements including first and second patch antenna resonating elements near-field-coupled to the wireless power receiving antenna; 
 a first amplifier coupled to the first patch antenna resonating element and a second amplifier coupled to the second patch antenna resonating element; 
 a first oscillator coupled to the first amplifier and a second oscillator coupled to the second amplifier; and 
 control circuitry configured to use the first oscillator and the first amplifier to provide a first drive signal to the first patch antenna resonating element and configured to use the second oscillator and the second amplifier to provide a second drive signal to the second patch antenna resonating element with a different phase than the first drive signal. 
 
     
     
       20. The wireless power transmitting device of  claim 19  wherein the patch antenna resonating elements extend in a staggered row along an axis and wherein each patch antenna resonating elements is elongated along a dimension that is perpendicular to the axis.

Description:
This application claims the benefit of provisional patent application No. 62/609,131, filed Dec. 21, 2017, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to power systems, and, more particularly, to wireless power systems for charging electronic devices. 
     BACKGROUND 
     In wireless charging systems, wireless power transmitting devices transmit power wirelessly to wireless power receiving devices. In some configurations, wireless power transmitting devices such as wireless charging mats are able to transmit power wirelessly to a variety of different wireless power receiving devices. The wireless power receiving devices each have rectifier circuitry for receiving wireless alternating-current (AC) power from the wireless charging mat. The rectifier circuitry is used in converting the received AC power into direct-current (DC) power. 
     SUMMARY 
     A wireless power system may use a wireless power transmitting device to transmit wireless power to a wireless power receiving device. The wireless power transmitting device has antennas such as patch antennas. The patch antennas are arranged in a staggered row that extends along an axis. Each patch antenna is elongated along a dimension that is perpendicular to the axis. 
     Multiple antennas may be coupled to a wireless power receiving antenna in the wireless power receiving device. Control circuitry in the wireless power transmitting device uses oscillator and amplifier circuitry to provide antennas that have been overlapped by the wireless power receiving antenna with drive signals. The drive signals are adjusted based on feedback from the wireless power receiving device to enhance power transmission efficiency. For example, drive signals provided to different antennas can be provided with different phases and/or magnitudes to enhance power transmission efficiency. 
     In some arrangements, the wireless power transmitting device includes inductive charging circuitry with one or more wireless power transmitting coils. Each coil may have loops of wire that surround a corresponding patch antenna resonating element. To suppress eddy currents that might otherwise be induced in the patch antenna resonating element during inductive wireless power transmission operations, the patch antenna resonating elements may each have one or more slots. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative wireless power system that includes a wireless power transmitting device and a wireless power receiving device in accordance with an embodiment. 
         FIG. 2  is a cross-sectional side view of an illustrative wireless power transmitting device and a corresponding wireless power receiving device in accordance with an embodiment. 
         FIG. 3  is a perspective view of an illustrative wireless power transmitting device patch antenna in accordance with an embodiment. 
         FIG. 4  is a top view of an illustrative wireless power transmitting device in accordance with an embodiment. 
         FIG. 5  is a flow chart of illustrative operations involved in operating a wireless power system of the type shown in  FIG. 1  in accordance with an embodiment. 
         FIG. 6  is a diagram showing illustrative multiplexing circuitry that may be incorporated into a wireless power receiving device to allow an antenna to be shared between communications circuitry and wireless power circuitry in accordance with an embodiment. 
         FIG. 7  is a circuit diagram of illustrative inductive wireless power circuitry of the type that can be used in the system of  FIG. 1  in accordance with an embodiment. 
         FIG. 8  is a top view of a portion of a wireless power transmitting device having an array of microwave antenna elements and an array of inductive wireless power transmitting coils in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A wireless power system has a wireless power transmitting device such as a wireless charging mat. The wireless power transmitting device wirelessly transmits power to a wireless power receiving device such as a wristwatch, cellular telephone, tablet computer, laptop computer, or other electronic equipment. The wireless power receiving device uses power from the wireless power transmitting device for powering the device and for charging an internal battery. 
     The wireless power transmitting device has an array of wireless power transmitting antennas arranged across a charging surface. During operation, the wireless power transmitting antennas such as microwave antennas are used to transmit wireless power signals that are received by a near-field-coupled wireless power receiving antenna in the wireless power receiving device. 
     An illustrative wireless power system (wireless charging system) is shown in  FIG. 1 . As shown in  FIG. 1 , wireless power system  8  includes a wireless power transmitting device such as wireless power transmitting device  10  and includes a wireless power receiving device such as wireless power receiving device  40 . Wireless power transmitting device  10  includes control circuitry  16 . Wireless power receiving device  40  includes control circuitry  46 . Control circuitry in system  8  such as control circuitry  16  and control circuitry  46  is used in controlling the operation of system  8 . This control circuitry includes processing circuitry associated with microprocessors, power management units, baseband processors, digital signal processors, microcontrollers, and/or application-specific integrated circuits with processing circuits. The processing circuitry implements desired control and communications features in devices  10  and  40 . For example, the processing circuitry may be used in determining power transmission levels, processing sensor data, processing user input, handling communications between devices  10  and  40  (e.g., sending and receiving data associated with wireless power transfer operating settings), selecting wireless power transmitting antennas, adjusting the phase and/or magnitude of drive signals applied to each transmitting antenna, and otherwise controlling the operation of system  8 . 
     Control circuitry in system  8  may be used to authorize power receiving devices to use power and ensure that authorized power receiving devices do not exceed maximum allowable power consumption levels. Control circuitry 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  is stored on non-transitory computer readable storage media (e.g., tangible computer readable storage media) in control circuitry  16  and/or  46 . 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  16  and/or  46 . 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. 
     Power transmitting device  10  may be a stand-alone power adapter (e.g., a wireless charging mat that includes power adapter circuitry), may be a wireless charging mat that is connected to a power adapter or other equipment by a cable, may be a portable device, may be equipment that has been incorporated into furniture, a vehicle, or other system, or may be other wireless power transfer equipment. Illustrative configurations in which wireless power transmitting device  10  is a wireless charging mat may sometimes be described herein as an example. 
     Power receiving device  40  may be a portable electronic device such as a wristwatch, a cellular telephone, a laptop computer, a tablet computer, or other electronic equipment. Power transmitting device  10  may be connected to a wall outlet (e.g., alternating current), may have a battery for supplying power, and/or may have another source of power. Power transmitting device  10  may have an AC-DC power converter such as power converter  14  for converting AC power from a wall outlet or other power source into DC power. DC power is used to power control circuitry  16 . During operation, a controller in control circuitry  16  uses power transmitting circuitry  28  to transmit wireless power to power receiving circuitry  50  of device  40 . 
     Power transmitting circuitry  28  has a transmitter such as transmitter  20 . Transmitter  20  includes circuitry that produces alternating-current drive signals such as one or more oscillators  22 . The frequency at which transmitter  20  supplies the alternating-current drive signals may be at microwave frequencies. For example, the frequency at which transmitter  20  supplies the alternating-current drive signals may be 1-5 GHz, 500 MHz to 5 GHz, about 2.4 GHz, at least 0.5 GHz (500 MHz), at least 1 GHz, at least 2 GHz, less than 3 GHz, less than 10 GHz, less than 100 GHz, less than 300 GHz, or other suitable frequency. 
     Oscillators  22  may produce output signals of adjustable magnitude and phase. Amplifier circuitry such as one or more corresponding amplifiers  24  (sometimes referred to as power amplifiers) amplify the drive signals produced by oscillators  22 . The output of transmitter  20  is supplied to one or more antennas  26 . In an illustrative embodiment, transmitter  20  may have N oscillators  22  and N corresponding power amplifiers  24 , each of which receives the output of a respective one of oscillators  22  and each of which supplies a corresponding one of N drive signals at its output. The N drive signals supplied at the output of the N power amplifiers  24  may have phase and magnitude attributes that are independently adjustable by control circuitry  16 . Each of the N drive signals is supplied to a respective one of N antennas  26 . The value of N may be at least 2, at least 5, at least 10, at least 15, at least 20, less than 50, less than 30, less than 20, less than 13, less than 8, or other suitable number. 
     By supplying antennas  26  with alternating-current drive signals, antennas  26  each produce corresponding electromagnetic output signals  30  (e.g., radio-frequency electromagnetic signals such as microwave signals). These signals are near-field coupled to corresponding wireless power receiving components in device  40 . For example, power receiving circuitry  50  may include a receiver such as receiver  52  with rectifier circuitry such as rectifier  54  coupled to one or more antennas such as antenna  56 . With one arrangement, receiving circuitry  50  includes a single antenna  56 . 
     When device  40  is resting on the charging surface of device  10 , antenna  56  is near-field coupled to one or more of antennas  26  in device  10  (e.g., antenna  56  may be capacitively coupled to one or more antennas  26  that are partially or fully overlapped by antenna  56 ). Due to the electromagnetic coupling between antennas  26  and antenna  56 , wireless power signals such as electromagnetic signals  30  that are transmitted by antennas  26  produce corresponding alternating-current signals in antenna  56 . Rectifier  54  rectifies these received alternating-current signals and produces corresponding direct-current (DC) output voltages. 
     The DC voltages produced by rectifier  54  can be used in charging a battery such as battery  42  and can be used in powering other components in device  40 . For example, device  40  may include input-output devices  44  such as a display, communications circuits, audio components, sensors, user input components such as buttons, microphones, touch and force sensors, and other components and these components may be powered by the DC voltages produced by rectifier  54  (and/or DC voltages produced by battery  42 ). 
     Device  10  and/or device  40  may communicate wirelessly. Device  10  may, for example, have wireless transceiver circuitry  18  that wirelessly transmits wireless communications signals such as Bluetooth® signals or other wireless data to device  40  using an antenna (e.g., an antenna in circuitry  18  that is separate from antennas  26 ). Wireless transceiver circuitry  18  may be used to wirelessly receive Bluetooth® signals or other wireless data signals that have been transmitted from device  40  using the antenna. 
     Device  40  may have wireless transceiver circuitry  48  that transmits wireless signals (e.g., Bluetooth® signals) to device  10  using an antenna. Receiver circuitry in wireless transceiver  48  may use this antenna to receive transmitted wireless communications signals (e.g., Bluetooth® wireless data) from device  12 . The antenna of transceiver  48  may be separate from antenna  56  or antenna  56  may be used both in receiving transmitted wireless communications data and in receiving wireless power signals. 
       FIG. 2  is a cross-sectional side view of system  8  in an illustrative configuration in which wireless power transmitting device  10  is transmitting wireless power to a single corresponding wireless power receiving device  40 . If desired, multiple wireless power receiving devices  40  may simultaneously receive power from device  10 . 
     As shown in  FIG. 2 , device  10  may include multiple wireless power transmitting antennas  26 . Each antenna  26  may be formed from a respective antenna resonating element  70  such as a patch antenna resonating element (e.g., antennas  26  may be patch antennas) and a shared antenna ground  82 . Each antenna  26  may have a feed formed from terminals  26 T. The terminals  26 T of each antenna  26  are coupled to the output of a corresponding amplifier  24  (FIG.  1 ). In some configurations, antennas  26  may be antennas other than patch antennas (e.g., inverted-F antennas, loop antennas, slot antennas, etc.). Antenna resonating elements  70  (e.g., patch antenna resonating elements) may sometimes be referred to as electrodes, patches, or metal plates. Elements  70  can be formed from metal foil, metal traces on printed circuits or dielectric carriers, or other conductive structures. 
     Device  10  of  FIG. 2  includes housing  72 . Housing  72  may include conductive materials such as metal, and dielectric materials (e.g., polymer, glass, ceramic, etc.). Upper portion  72 ′ (e.g., a planar cover member) overlaps antennas  26  (e.g., resonating elements  70 ) and forms charging surface  72 C. One or more devices such as device  40  rest on charging surface  72 C during wireless power transfer operations. 
     Portion  72 ′ of housing  12  is formed from a dielectric such as a polymer, glass, or ceramic to allow signals  30  to pass from antennas  70  to power receiving circuitry  50  in device  40  such as power receiving antenna  56 . Power receiving antenna  56  includes power receiving antenna resonating element  56 E (e.g., a patch antenna element, slot antenna element, or other antenna resonating element). Antenna resonating element  56 E and ground  56 G form wireless power receiving antenna  56 . During operation, wireless signals are received by antenna  56  through portion  72 ′. Alternating-current signals received with antenna  56  are supplied to rectifier  54  ( FIG. 1 ) via antenna feed terminals such as antenna terminals  56 T. Device  40  has a housing such as housing  80  (e.g., a housing formed from metal, glass, polymer, and/or ceramic, etc.). Antenna  56  may be formed from a conductive portion of housing  80 , from metal traces on a dielectric substrate (e.g., a printed circuit, plastic carrier, glass member, dielectric housing structures, etc.), or from other conductive structures. If desired, portions of housing  80  may be formed from dielectric to allow signals to pass through housing  80  to antenna  56 . 
     Antenna resonating elements  70  in device  10  are formed from conductive structures such as metal traces that have been patterned onto a substrate such as substrate  76 . In an embodiment, the metal traces form a set of rectangular metal patches (e.g., antenna resonating elements  70  are patch antenna resonating elements and antennas  56  are patch antennas). Other configurations may be used for antenna resonating elements  70 , if desired. 
     Substrate  76  is a dielectric substrate with one or more layers (e.g., a flexible printed circuit formed from a sheet of flexible polymer material such as a layer of polyimide or other flexible polymer layer, a rigid printed circuit substrate formed from a material such as fiberglass-filled epoxy, a plastic carrier, a glass layer, etc.). Ground plane  82  is formed from a planar layer of metal traces (e.g., a ground plane layer in printed circuit  76  that is separated by a height H from the metal traces forming antenna resonating elements  70 ). 
     The value of height H and other attributes of antennas  26  such as the shape and dimensions of antenna resonating elements  70  are configured so that the free-space efficiency of antennas  26  (e.g., the efficiency of each antenna  26  when device  40  and antenna  56  are not present) is less than a small upper threshold value Effmax. The value of Effmax may, as an example, be reduced by configuring antenna resonating elements  70  to have an elongated shape (e.g., an elongated rectangular shape with small width that does not support fringing fields with the ground of the antenna). The value of Effmax may be 1%, 2%, 5%, 0.1-4%, at least 0.3%, at least 0.05%, less than 10%, or other suitable low value. When device  40  lies on charging surface  72 C so that antenna resonating element  56 E of antenna  56  overlaps one or more of antennas  26  (e.g., one or more of antenna resonating elements  70 ), the efficiency of the overlapped antennas  26  increases significantly (e.g., to at least 10%, to at least 20%, at least 50%, at least 70%, at least 80%, at least 90%, at least 95%, less than 99.99%, less than 99%, or other suitable amount). Efficiency increases by a factor of at least 2, at least 3, at least 5, at least 10, at least 30, or other suitable value when antenna  56  is present. 
     As a result, device  10  will not radiate significant wireless power as signals  30  in the absence of device  40 . When device  40  and antenna  56  are present (e.g., when antenna resonating element  56 E overlaps one or more elements  70  in one or more respective antennas  26  and is capacitively coupled to those elements), the overlapped antennas  26  will be near-field coupled (e.g., capacitively coupled) to antenna  56  and will allow efficient transmission of wireless power from device  10  to device  40 . When device  40  is not present, however, the efficiency of antennas  26  will drop sufficiently to prevent significant power from being wirelessly transmitted. In some configurations, control circuitry  16  may measure the impedance of each of antennas  26  (e.g., the amount of near-field coupling of each of antennas  26  to antenna  56 ) and to use this measured impedance information in adjusting the drive signals supplied to antennas  26  using transmitter  20 . If, as an example, a given antenna  26  is not coupled to any receiving device antennas, no drive signals may be provided to that antenna. Control circuitry  16  can also adjust the drive signals applied to each antenna  26  based on feedback from device  40  (e.g., information on power transfer efficiency between device  10  and device  40  that is gathered using feedback from device  40 ). Feedback information can be used in real time to make adjustments to the signals supplied to antennas  26  to enhance power transfer efficiency. 
     A perspective view of an illustrative patch antenna configuration for antenna  26  is shown in  FIG. 3 . As shown in  FIG. 3 , antenna resonating element  70  is located a distance (height) H from antenna ground  82 . Antenna terminals  26 T form an antenna feed for antenna  26 . Antenna resonating element  70  of  FIG. 3  has a rectangular shape characterized by a length L and width W. Other shapes (circular, oval, square, hexagonal, etc.) may be used for forming patch antenna resonating elements, if desired. Length L may be at least 2 times greater than width W or at least 3 or 5 times longer than width W (as examples). This configuration (a narrow width arrangement) helps reduce fringing fields and therefore reduces free-space antenna efficiency so that wireless emissions are low when device  40  is not present. With an illustrative arrangement, length L is 40 mm (e.g., at least 25 mm, at least 35 mm, less than 50 mm, less than 65 mm, etc.) and width W is 12 mm (e.g. at least 5 mm, at least 8 mm, at least 10 mm, less than 15 mm, less than 18 mm, less than 25 mm, etc.). Height H may be about 0.01-10 mm, at least 0.05 mm, at least 0.1 mm, at least 0.5 mm, less than 6 mm, less than 4 mm, less than 2 mm, etc.). The aspect ratio of element  70  (L/W) is about 3.3, at least 2, at least 3, less than 3.5, less than 4, 1.5-5, or other suitable length-to-width value. 
     To provide satisfactory coverage for a variety of wireless power receiving devices on charging surface  72 C, multiple antenna resonating elements  70  (multiple antennas  26 ) may be formed across surface  72 C. As shown in  FIG. 4 , for example, charging surface  72 C may have an elongated shape (rectangular, oval, rectangular with curved corners, etc.) and may be characterized by longitudinal axis  90 . Antenna resonating elements  70  may be arranged in a row along the length of device  10  (e.g., a single staggered row). Configurations, which elements  70  are arranged in multiple staggered rows (e.g., to form a checkerboard of elements  70 ), or in which elements  70  are arranged in one or more unstaggered rows or other patterns may also be used, if desired. 
     In the arrangement of  FIG. 4 , elements  70  are spaced evenly along the length of surface  72 C (e.g., along longitudinal axis  90 , parallel to the X axis of  FIG. 4 ). To widen the coverage (along axis Y) of antennas  26  without increasing the number of antennas  26  that are used, the positions of elements  70  relative to axis Y are staggered. Alternating odd and even resonating elements  70  may, for example, be placed so that their centers  92  lie respectively above or below axis  90  (on opposing sides of axis  90 ), which bisects surface  72 C. By alternating the placement of resonating elements  70  in this way, relatively large lateral coverage (along axis Y) can be achieved without increasing the number of power amplifiers and resonating elements  70  that are used for a given surface area of charging surface  72 C. The resonating element pattern of  FIG. 4  also helps ensure satisfactory near-field coupling between device  10  (elements  70 ) and a variety of different wireless power receiving devices  40  (e.g., antennas in tablets, cellular telephones, watches, stylus devices, earbuds, earbud cases, etc.). 
     To enhance wireless power transmission efficiency, control circuitry  16  adjusts the drive signal supplied to each of antennas  26  (e.g., by adjusting drive signal phase and/or magnitude using oscillators  22  and/or amplifiers  24  of transmitter  20 ). Control circuitry  16  may, as an example, only transmit power using resonating elements  70  that are coupled to a wireless power receiving device antenna. Coupling can be measured using measurement circuitry in control circuitry  16  (e.g., impedance measurement circuitry that determines whether the impedance of each antenna  26  has been perturbed by an overlapping antenna element  56 E, reflected power measurement circuitry that measures how much transmitted power is reflected back from a given antenna when power is provided to that antenna, etc.), using feedback data transmitted wirelessly from device  40  to device  10  (e.g., using transceiver circuitry  48  and transceiver circuitry  18 ), using sensors that detect overlapping objects such as devices  40  (e.g., electromagnetic sensors, optical sensors, etc.), and/or using other suitable circuitry that measures capacitive coupling between each of elements  70  and elements  56 E on charging surface  72 C. In some configurations, bidirectional wireless communications between device  10  and device  40  may be used to establish the type of power receiving device  40  that is present on device  10  and associated wireless power transmission settings to use in transmitting wireless power. 
     Consider, as a first example, a scenario in which a wireless power receiving device has an antenna with a resonating element (resonating element  56 E 1 ) that evenly overlaps parts of first element  70 - 1  and second element  70 - 2 . In this situation, control circuitry  16  will transmit wireless power using overlapped elements  70 - 1  and  70 - 2 , while the remaining elements  70  under surface  72 C are unpowered. To help enhance wireless power transmission efficiency in this scenario, control circuitry  16  can transmit wireless power by applying drive signals of equal magnitude and identical phase P 1  (within 1%, 2%, 10%, or other small threshold variation). 
     As a second example, consider a scenario in which a wireless power receiving device antenna has a resonating element (resonating element  56 E 2 ) that unevenly overlaps elements  70 - 3  and  70 - 4 . Element  70 - 4  may, as an example, be overlapped more than element  70 - 3 . To help enhance wireless power transmission efficiency the phase and/or magnitude of the drive signals applied to elements  70 - 3  and  70 - 4  with transmitter  20  may be different. As an example, the drive signal applied by control circuitry  16  to element  70 - 3  may have a first phase P 2  and the drive signal applied by control circuitry  16  to element  70 - 4  may have a second phase P 3  that is different than P 2 . 
     The drive signals (phase and/or magnitude, etc.) applied to each element  70  can be adjusted in real time based on feedback from device  40  to help enhance wireless power transmission efficiency. A flow chart of illustrative operations involved in enhancing wireless power transmission efficiency using feedback information is shown in  FIG. 5 . 
     During the operations of block  100 , transmitting device  10  uses power transmitting circuitry  28  to transmit wireless power Ptx to wireless power receiving device  40 . Wireless power receiving device  40  receives corresponding power Prx with wireless power receiving circuitry  50 . The amount of power that is received for a given transmitted power is influenced by factors such as the configurations of antennas  26  and  56 , the physical location of device  40  on charging surface  72 , and the drive signals applied to the antennas in device  10 . 
     During the operations of block  102 , control circuitry  46  of device  40  uses wireless communications circuitry such as transceiver  48  (e.g., a radio-frequency transceiver such as a Bluetooth® transceiver or other suitable wireless communications circuit) to transmit feedback to device  10 . In particular, transceiver  48  may be used in transmitting information to corresponding wireless transceiver circuitry  18  of device  10  on the value of received power Prx. Control circuitry  16  of device  10  uses the values of Ptx and Prx to determine the current power transmission efficiency Ptx/Prx. Power transmission efficiency measurements can be gathered while device  10  is transmitting wireless power using multiple antennas  26  (e.g., using first and second elements  70  that are coupled to element  56 E). The drive signals applied to each active element  70  can be selected based on coupling measurements (e.g., impedance measurements made with control circuitry  16 ) and/or the feedback from device  40 . 
     During the operations of block  104 , device  10  uses control circuitry  16  adjust the drive signals (e.g., drive signal phase and/or magnitude) to each element  70  (e.g., each element  70  coupled to element  56 E). Adjustments to drive signals can be made to enhance to wireless power transmission efficiency. In some arrangement, test sample adjustments (adjustments made to gather testing information) can be made to drive signals to help device  10  evaluate wireless power transmission efficiency over a range of possible drive conditions. Device  10  may, for example, increase or decrease phase P 2  relative to phase P 3  momentarily to evaluate whether phase P 2  is currently too low or too high. As shown by line  106 , which indicates how processing may loop back to the operations of block  100 , the process of adjusting the drive signal to each antenna in device  10  and evaluating the resulting wireless power transmission efficiency (Prx/Ptx) that is achieved may be performed continuously during wireless power transmission operations. 
     In some arrangements for device  40 , wireless power and wireless communications are handled using separate respective antennas. In other configurations, all or part of a wireless power receiving antenna can be shared with all or part of a wireless communications antenna. As shown in the illustrative arrangement of  FIG. 6 , for example, antenna  56  can be shared between communications transceiver  48  and wireless power receiver  52  using multiplexing circuitry  120 . 
     In an illustrative embodiment, system  8  includes inductive wireless power circuitry, as shown in  FIG. 7 . In this type of arrangement, device  10  has one or more inductive wireless power transmitting circuits such as circuit  130  each of which includes an inverter  132  for supply alternating-current drive signals to a corresponding resonant circuit formed from a wireless power transmitting coil  134  and one or more associated capacitors such as illustrative capacitor  136 . This produces alternating-current electromagnetic signals (e.g., magnetic fields) that are received by any overlapping (magnetically coupled) inductive wireless power receiving devices  40 . Devices  40  that receive wireless power from coil  134  have corresponding wireless power receiving coils such as coil  138  of  FIG. 7  in a resonant circuit that includes one or more capacitors such as capacitor  140 . Rectifier circuitry such as rectifier  142  is coupled to each resonant circuit (e.g., each wireless power receiving coil  138  and capacitor(s)  140 ). During operation, wireless power is transmitted using coil  134  and received by coil  138  at inductive wireless power transmission frequencies (e.g., 50 kHz to 500 kHz, at least 100 kHz, at least 200 kHz, less than 10 MHz, less than 1 MHz, less than 400 kHz, or other suitable inductive wireless power transmission frequencies). 
     By incorporating both inductive wireless power transmitting coils  134  and wireless power transmitting antennas  26  into device  10 , device  10  can support wireless charging with wireless power receiving devices that support only inductive charging, wireless power receiving devices that support wireless charging only using antennas  26  (e.g., capacitive coupling arrangements), and wireless power receiving devices that include one or more power receiving coils  138  in addition to one or more antennas  56 . 
       FIG. 8  is a top view of device  10  in an illustrative configuration in which both inductive wireless power transmitting coils  134  and antennas  56  with antenna resonating elements  70  have been incorporate into device  10 . As shown in  FIG. 8 , antenna resonating elements  70  can be placed in the centers of coils  134  so that each element  70  is surrounded by the loops of conductive lines (wires, metal traces, etc.) of a respective one of coils  134 . To help reduce eddy currents during inductive wireless power transmission operations, antenna resonating elements  70  can be formed from thin metal (e.g., metal traces with a thickness of less than 1 micron, less than 0.5 microns, less than 0.2 microns, less than 0.1 microns, less than 0.05 microns, at least 0.01 microns, or other suitable thickness) and/or can have slots  150  that pass partway through or fully through elements  70  (see, e.g., element  70 ′). At lower frequencies such as those associated with inductive charging, slots  150  form open circuits (high impedance structures) and the presence of slots  150  disconnects regions of element  70 ′ from each other, thereby blocking eddy current formation. At higher frequencies such as those associated with wireless power transfer using antennas  26  and  56 , the capacitances associated with slots  150  are short circuits, effectively bridging slots  150  and electrically connecting all of the different portions of each element  70  together (e.g., all of the portions of element  70 ′ of  FIG. 8  are electrically shorted to each other). As a result, the portions of each element  70  that are separated by slots  150  will be electrically joined and will form an effective antenna resonating element  70  for a corresponding antenna  26 . 
     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: 20180222
Publication Date: 20200714
Grant Date: 20200714
Priority Date: 20171221
Inventors: JIANG, BING
SCHAUER, MARTIN
SEN, INDRANIL S.
JADIDIAN, Jouya
NEUMANN, MARK D.
NARANG, MOHIT
PATHAK, VANEET
JIANG, YI
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/23", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/23", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "H02J50/23", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0407", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/23", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/065", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B5/0037", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/065", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0407", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/23", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/43", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 66949014