Abstract: Methods, systems, and apparatus, including computer programs encoded on computer-storage media, for wireless charging using time-division multiplexing. In some implementations, a wireless charger is configured to concurrently charge multiple devices by providing power wirelessly to individual devices in different time periods. The wireless charger can perform time-division multiplexing by selectively directing the output of a single driver circuit to different power transfer coil segments at different times. The wireless charging sessions of multiple devices can be maintained by repeating a pattern of activating different power transfer coil segments one by one in successive time periods.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer-storage media, for wireless charging using time-division multiplexing. In some implementations, a wireless charger is configured to concurrently charge multiple devices by providing power wirelessly to individual devices in different time periods. The wireless charger can perform time-division multiplexing by selectively directing the output of a single driver circuit to different power transfer coil segments at different times. The wireless charging sessions of multiple devices can be maintained by repeating a pattern of activating different power transfer coil segments one by one in successive time periods.

Abstract: An example mobile computing device includes at least one processor, a battery, and a device enclosure. The device enclosure at least partially encloses the mobile computing device. At least one portion of the device enclosure comprises at least one first element, a region that is at least partially formed in and at least partially surrounded by the at least one first element, at least one insulative element formed in the region, wherein the at least one insulative element includes at least one electrically insulative material, and a wireless charging module included in the region. The wireless charging module is configured to wirelessly communicate with an external charging device to induce a current in the wireless charging unit, and wherein the current is used to charge the battery of the mobile computing device.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer-storage media, for wireless charging using time-division multiplexing. In some implementations, a wireless charger is configured to concurrently charge multiple devices by providing power wirelessly to individual devices in different time periods. The wireless charger can perform time-division multiplexing by selectively directing the output of a single driver circuit to different power transfer coil segments at different times. The wireless charging sessions of multiple devices can be maintained by repeating a pattern of activating different power transfer coil segments one by one in successive time periods.

Abstract: This document describes techniques and apparatuses directed at reducing inductive-charging power loss. In aspects, a mobile device includes a multi-layer flexible printed circuit board (FPCB) coil that forms a receiver coil having a Litz-wire structure. The FPCB coil includes a multi-trace bundle, having traces systematically routed throughout the different layers of the FPCB coil to reduce eddy current losses.

Abstract: Methods, systems, and techniques for safely controlling wireless charging in the presence of a foreign object are presented. A method includes determining a power difference between a power transmitted by a wireless charger and a power received by an electronic device, determining a level of misalignment of the electronic device with respect to the wireless charger; estimating an amount of power difference due to the level of misalignment of the electronic device with respect to the wireless charger, adjusting a power difference threshold for the wireless charger based on the estimated amount of power difference, and controlling operation of the wireless charger based on the power difference and the adjusted power difference threshold.

Abstract: This document describes techniques and apparatuses directed at reducing inductive-charging power loss. In aspects, a mobile device includes a multi-layer flexible printed circuit board (FPCB) coil that forms a receiver coil having a Litz-wire structure. The FPCB coil includes a multi-trace bundle, having traces systematically routed throughout the different layers of the FPCB coil to reduce eddy current losses.

Abstract: A wireless power transfer system is provided. The wireless power transfer system comprises a resonator comprising a capacitor. The capacitor comprises at least two active electrodes; and a passive electrode adjacent the active electrodes and configured to encompass the active electrodes to at least partially eliminate environmental influences affecting the active electrodes and to increase the overall capacitance of the system. The resonator further comprises at least one inductive coil electrically connected to the active electrodes, wherein the resonator is configured to extract power from a generated electric field via resonant electric field coupling.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer-storage media, for improving wireless charging. In some implementations, an electronic device determines a power demand of the electronic device. The electronic device includes a wireless power receiver including a wireless power receiving coil configured to receive power through inductive coupling with a wireless charge. The electronic device determines an operating voltage or operating frequency for the wireless charger based on the power demand of the electronic device. The electronic device sends, to the wireless charger, data indicating the operating voltage or operating frequency for the wireless charger.

Abstract: A wireless power transfer system is provided. The wireless power transfer system comprises a resonator comprising a capacitor. The capacitor comprises at least two active electrodes; and a passive electrode adjacent the active electrodes and configured to encompass the active electrodes to at least partially eliminate environmental influences affecting the active electrodes and to increase the overall capacitance of the system. The resonator further comprises at least one inductive coil electrically connected to the active electrodes, wherein the resonator is configured to extract power from a generated electric field via resonant electric field coupling.

Abstract: A computing device can include a housing, a display secured by the housing, a charging coil included in a back side of the housing, the back side of the housing being on an opposite side from the display, and at least one magnet adjacent to the charging coil.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer-storage media, for improving wireless charging. In some implementations, an electronic device determines a power demand of the electronic device. The electronic device includes a wireless power receiver including a wireless power receiving coil configured to receive power through inductive coupling with a wireless charge. The electronic device determines an operating voltage or operating frequency for the wireless charger based on the power demand of the electronic device. The electronic device sends, to the wireless charger, data indicating the operating voltage or operating frequency for the wireless charger.

Abstract: A wireless power transfer system is provided. The wireless power transfer system comprises a resonator comprising a capacitor. The capacitor comprises at least two active electrodes; and a passive electrode adjacent the active electrodes and configured to encompass the active electrodes to at least partially eliminate environmental influences affecting the active electrodes and to increase the overall capacitance of the system. The resonator further comprises at least one inductive coil electrically connected to the active electrodes, wherein the resonator is configured to extract power from a generated electric field via resonant electric field coupling.

Abstract: Methods, systems, and techniques for safely controlling wireless charging in the presence of a foreign object are presented. A method includes determining a power difference between a power transmitted by a wireless charger and a power received by an electronic device, determining a level of misalignment of the electronic device with respect to the wireless charger; estimating an amount of power difference due to the level of misalignment of the electronic device with respect to the wireless charger, adjusting a power difference threshold for the wireless charger based on the estimated amount of power difference, and controlling operation of the wireless charger based on the power difference and the adjusted power difference threshold.

Abstract: A wireless electric field power transmission system comprises: a transmitter comprising a transmitter antenna, the transmitter antenna comprising at least two conductors defining a volume therebetween; and at least one receiver, wherein the transmitter antenna transfers power wirelessly via electric field coupling when the at least one receiver is within the volume.

Abstract: A wireless electric field power transmission system comprises a transmitter comprising a transmit resonator and a transmit capacitive balun, and at least one receiver comprising a receive resonator and a receive capacitive balun. The transmit capacitive balun is configured to transfer power to the transmitter resonator, the transmit resonator is configured to transfer the power to the receive resonator, and the receive resonator is configured to extract the power to the receive capacitive balun via electric field coupling.

Abstract: A wireless electric field power transmission system comprises: a transmitter comprising a transmitter antenna, the transmitter antenna comprising at least two conductors defining a volume therebetween; and at least one receiver, wherein the transmitter antenna transfers power wirelessly via electric field coupling when the at least one receiver is within the volume.

Abstract: A wireless electric field power transmission system comprises: a transmitter comprising a transmitter antenna, the transmitter antenna comprising at least two conductors defining a volume therebetween; and at least one receiver, wherein the transmitter antenna transfers power wirelessly via electric field coupling when the at least one receiver is within the volume.

Abstract: A hybrid resonator comprises capacitive electrodes; and an induction coil electrically connected to the capacitive electrodes. The capacitive electrodes and the induction coil are configured to: responsive to a generated field, extract power from the generated field; and responsive to the extracted power, generate a field.

Abstract: A wireless electric field power transmission system comprises a transmitter comprising a transmit resonator and a transmit capacitive balun, and at least one receiver comprising a receive resonator and a receive capacitive balun. The transmit capacitive balun is configured to transfer power to the transmitter resonator, the transmit resonator is configured to transfer the power to the receive resonator, and the receive resonator is configured to extract the power to the receive capacitive balun via electric field coupling.