PATENT DOCUMENT

Publication Number: US-10608468-B2
Application Number: US-201715611622-A
Country: US
Kind Code: B2

Title: Wireless charging systems with in-band communications

Abstract:
A wireless power transmitting device may have control circuitry that supplies drive signals to a coil to produce wireless power signals. The wireless power receiving device may have a coil that receives the transmitted wireless power signals from the wireless power transmitting device. The wireless power receiving device may have a rectifier that rectifies signals received by the coil in the wireless power receiving device and that provides a rectified voltage to a capacitor. A charger in the wireless power receiving device may charge a battery in the device using the rectified voltage. When it is desired to convey information to the wireless power transmitting device, the wireless power transmitting device may cease the transmission of wireless power and the wireless power receiving device may modulate transistors in the rectifier to transmit data to the wireless power transmitting device.

Claims:
What is claimed is: 
     
       1. An electronic device configured to receive wirelessly transmitted power signals from a power transmitting device, comprising:
 a coil configured to receive the wirelessly transmitted power signals; 
 a rectifier coupled to the coil, wherein the rectifier has transistors configured to rectify the power signals and produce a corresponding rectified direct-current voltage; 
 a capacitor configured to be charged by the rectified direct-current voltage; and 
 control circuitry having a data transmitter configured to transmit data to the power transmitting device by applying a series of current pulses to the coil using the transistors in the rectifier while the coil is not receiving the wirelessly transmitted power signals. 
 
     
     
       2. The electronic device of  claim 1  wherein the transistors of the rectifier comprise first and second transistors coupled in series across the capacitor. 
     
     
       3. The electronic device of  claim 2  further comprising an additional capacitor, wherein the first and second transistors are coupled at a node, wherein the additional capacitor is coupled to the node, and wherein the coil has a terminal coupled to the additional capacitor. 
     
     
       4. The electronic device of  claim 2  further comprising first and second additional capacitors, wherein the first and second transistors are coupled at a node and wherein the first additional capacitor is coupled to the node and wherein the second additional capacitor is coupled to ground by a switch in the data transmitter. 
     
     
       5. The electronic device of  claim 2  further comprising:
 a charger that is configured to receive the rectified direct-current voltage and that is configured to recharge a battery using the rectified direct-current voltage. 
 
     
     
       6. The electronic device of  claim 1  wherein the control circuitry comprises a data receiver circuit configured to receive data through the coil that has been transmitted wirelessly from the power transmitting device while the coil is receiving the wirelessly transmitted power signals. 
     
     
       7. The electronic device of  claim 1  wherein the data transmitter is configured to transmit data bits that are each represented by at least two of the pulses. 
     
     
       8. The electronic device of  claim 1  further comprising a display that is configured to display images without interruption while the data transmitter transmits data to the power transmitting device. 
     
     
       9. A method for communicating between a wireless power receiving device and a wireless power transmitting device, comprising:
 with the wireless power receiving device, receiving transmitted wireless power from the wireless power transmitting device with a receiving device coil and a rectifier that has at least a pair of transistors coupled in series across a capacitor in the wireless power receiving device; 
 with the wireless power receiving device, charging the capacitor in the wireless power receiving device using the received transmitted wireless power; and 
 transmitting data to the wireless power transmitting device with a control circuit in the wireless power receiving device by applying signal pulses to the receiving device coil while wireless power transmission from the wireless power transmitting device is paused and while the capacitor is supplying power to the control circuit. 
 
     
     
       10. The method of  claim 9  wherein transmitting the data comprises transmitting data to the wireless power transmitting device by applying current pulses to the receiving device coil that have a duration of 0.1 microseconds to 10 microseconds. 
     
     
       11. The method of  claim 9  wherein transmitting the data to the wireless power transmitting device with the control circuit comprises transmitting the data to the wireless power transmitting device with the control circuit containing data bits that are each represented by at least two of the pulses. 
     
     
       12. The method of  claim 9  further comprising:
 with the wireless power transmitting device, transmitting the wireless power from a transmitting device coil. 
 
     
     
       13. The method of  claim 12  further comprising:
 with a data receiver in the wireless power transmitting device, receiving the transmitted data. 
 
     
     
       14. The method of  claim 13  wherein each of the pulses induces a ringing signal in the transmitted device coil and wherein receiving the transmitted data comprises detecting the ringing signals. 
     
     
       15. The method of  claim 9  wherein the wireless power receiving device comprises a display configured to display images, the method further comprising:
 displaying the images uninterruptedly on the display while the wireless power transmission from the wireless power transmitting device is paused. 
 
     
     
       16. An electronic device that is configured to operate in a system with a wireless power transmitting device, comprising:
 a coil that is configured to receive wireless power from the wireless power transmitting device; 
 a rectifier coupled to the coil; 
 a capacitor that is configured to be charged with wireless power received from the coil using the rectifier; and 
 a data transmitter configured to transmit data bits to the wireless power transmitting device while wireless power transmission by the wireless power transmitting device is paused by applying signal pulses to the coil that induce signal ringing in the wireless power transmitting device. 
 
     
     
       17. The electronic device of  claim 16  wherein the transmitted data bits include data bits that are each represented by at least two of the signal pulses. 
     
     
       18. The electronic device of  claim 17  wherein the data transmitter is configured to transmit the data bits by applying signal pulses to the coil that each have a duration of 0.1 to 10 microseconds. 
     
     
       19. The electronic device of  claim 16  further comprising:
 a battery; and 
 a charger that is configured to charge the battery with wireless power received from the wireless power transmitting device. 
 
     
     
       20. The electronic device of  claim 16  further comprising an additional capacitor, wherein the additional capacitor is coupled between the coil and a node and wherein the data transmitter is configured to apply the signal pulses to the node. 
     
     
       21. The electronic device of  claim 16  wherein the rectifier is configured to produce a direct-current rectified voltage in response to receipt of the wireless power and is configured to supply the direct-current rectified voltage to the capacitor. 
     
     
       22. The electronic device of  claim 16  further comprising a display, wherein the display is configured to display images uninterruptedly while the wireless power transmission by the wireless power transmitting device is paused. 
     
     
       23. The electronic device of  claim 16 , wherein the signal ringing induced at the wireless power transmitting device is demodulated by the wireless power transmitting device to obtain a code corresponding to the data bits transmitted by the data transmitter.

Description:
This application claims the benefit of provisional patent application No. 62/355,707, filed Jun. 28, 2016, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to charging systems, and, more particularly, to systems for charging electronic devices. 
     BACKGROUND 
     In a wireless charging system, a wireless power adapter may use a coil to wirelessly transmit power to a wireless power receiving device. The wireless power receiving device may have a coil and a rectifier. The coil receives wirelessly transmitted power signals from the wireless power adapter. The rectifier converts the received signals into direct-current (DC) power. 
     It may sometimes be desirable to transmit data from a wireless power receiving device to a wireless power adapter. So-called in-band communications schemes have been developed that allow wireless power receiving devices to communicate with wireless power devices. In a typical in-band communications scheme, a switching circuit that is coupled to the coil in the receiving device is used to modulate the load across the coil. The wireless power adapter can detect the modulated signal using a voltage sensing circuit coupled to a coil in the wireless power adapter. 
     In-band communications schemes that are based on this type of load modulation may not always be reliable. For example, if electromagnetic coupling between the wireless power adapter and the wireless power receiving device is poor, the voltage sensing circuit in the wireless power adapter may not be able to detect the modulated signal from the wireless power receiving device. 
     SUMMARY 
     A system is provided in which a wireless power transmitting device may transmit power wirelessly to a wireless power receiving device. The wireless power transmitting device may have control circuitry that supplies drive signals to a coil to produce wireless power signals. The wireless power receiving device may have a coil that receives the transmitted wireless power signals from the wireless power transmitting device. The wireless power transmitting device and the wireless power receiving device may communicate wirelessly using the same coils that are used in transmitting and receiving wireless power. 
     The wireless power receiving device may have a rectifier that rectifies signals received by the coil in the wireless power receiving device and that provides a corresponding rectified voltage to a capacitor. A charger in the wireless power receiving device may charge a battery in the device using the rectified voltage. When it is desired to convey information to the wireless power transmitting device, the wireless power transmitting device may pause transmission of wireless power and the wireless power receiving device may modulate transistors in the rectifier, thereby transmitting data in band to wireless power transmitting device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative wireless charging system that includes a wireless power adapter and an electronic device that receives power from the power adapter in accordance with an embodiment. 
         FIG. 2  is a circuit diagram of illustrative devices in a system of the type shown in  FIG. 1  in accordance with an embodiment. 
         FIG. 3  is a graph showing signals associated with operating a wireless charging system in accordance with an embodiment. 
         FIG. 4  is a flow chart of illustrative operations involved in using a wireless charging system in accordance with an embodiment. 
         FIG. 5  is a graph of signals associated with transmitting data from a wireless power receiving device to a wireless power transmitting device in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A wireless power system may have a power transmitting device such as a wireless power adapter or other equipment. The wireless power transmitting device may wirelessly transmit 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 may use power from the wireless power adapter for powering control circuitry and for charging an internal battery. 
     An illustrative wireless power system (wireless charging system) is shown in  FIG. 1 . As shown in  FIG. 1 , wireless power system  10  may include a wireless power transmitting device such as wireless power transmitting device  12  and may include a wireless power receiving device such as wireless power receiving device  24 . 
     Power transmitting device  12  may be a stand-alone power adapter, may be a wireless charging mat that is coupled 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  12  is a power adapter may sometimes be described herein as an example. 
     Power receiving device  24  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  12  may be coupled to a wall outlet or other source of alternating-current (AC) power and/or may have a battery for supplying power. Power transmitting device  12  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 may be used to power control circuitry  16 . During operation, a controller in control circuitry  16  may turn on and off switching circuitry (e.g., transistors) to create AC signals through coil  22 . As the AC signals pass through coil  22 , electromagnetic signals  26  are produced that are received by corresponding coil  28  in power receiving device  24 . When it is desired to transmit data from device  12  to device  24 , data transmitter circuitry  18  may be used in modulating the signals that are supplied to coil  22  using a modulation scheme such as a frequency-shift keying (FSK) modulation scheme. Control circuitry  30  of power receiving device  24  may use a data receiver circuit such as data receiver circuit  32  to demodulate the modulated signal pulses from transmitter  18  (e.g., circuit  32  can demodulate the FSK signals from circuit  18 ). When it is desired to transmit data from device  24  to device  12 , data transmitter circuit  34  of device  24  may be used in producing signals that are transmitted by coil  28  to coil  22  of device  12  and that are demodulated by data receiver  20  of device  12 . 
     During power transmission operations, coil  28  supplies received AC power signals to rectifier  36 . Rectifier  36  contains rectifying circuitry such as bridge circuit  40 . Bridge circuit  40  has rectifying components such as synchronous rectification metal-oxide-semiconductor transistors  38  arranged in a bridge network between input terminals IN and output terminals OUT. The bridge network may have any suitable number of transistors  38  (e.g., two transistors  38 , four transistors  38 , etc.). The configuration of  FIG. 1  is illustrative. 
     Input terminals IN may receive AC power signals from coil  28 . Transistors  38  may be turned on and off by control circuitry  30  in synchronization with the AC power signals from coil  28  to rectify the AC power signals (e.g., transistors  38  of bridge circuit  40  and rectifier  36  may be operated using a synchronous rectification scheme to produce rectified signals at output OUT). A capacitor and a charger circuit may be coupled to output OUT and may be used to store received power, to smooth out signal ripples, and to provide power to a battery in device  24 . 
     Device  24  may include display  29  for displaying images to a user of device  24  and may contain other input-output devices such as sensors (e.g., force sensors, touch sensors, light-based proximity sensors, capacitance-based proximity sensors, capacitive touch sensors, force sensors, magnetic sensors, gyroscopes, accelerometers, gas pressure sensors, temperature sensors, ambient light sensors, image sensors, etc.), may include buttons, keypads, trackpads, and other input devices, may include audio components, status-indicator lights, and/or other electrical components. 
     When it is desired to transmit data from device  24  to device  12 , device  12  may cease (stop) transmission of power. Power transmission may be stopped for a relatively short amount of time (e.g., 5-50 ms) or other suitable period of time. During this time, any components in device  24  that have been powered up and are active (e.g., a display such as display  29  that is displaying images to a user, an audio device that is presenting audio to the user, etc.) may continue to operate without interruption, because the smoothing capacitor (e.g., capacitor Cout) in rectifier  36  and/or the battery in device  24  (e.g., battery  42 ) are able to supply power to these components even in the absence of received wireless power from device  12 . As a result, a user&#39;s interaction with device  24  will not be disrupted. When device  24  is displaying a battery charging indicator on display  29 , the battery charging indicator would also ignore the brief stoppage of incoming wireless power. For example, the battery charging indicator forgoes briefly transitioning from an indication of charging, to non-charging, and back to charging operation. These aspects allow data to be transmitted from device  24  to device  12  periodically (e.g., to provide real-time feedback on charging parameters, etc.) without perceptible interruption to the user&#39;s interaction with device  24 . Data may also be transmitted from device  24  to device  12  upon initially transmitting power from device  12  to device  24  (e.g., to provide a device identifier from device  24  to device  12 , etc.). 
     While device  12  is not transmitting wireless power to device  24 , data transmitter circuit  34  of device  24  may modulate transistors  38  in rectifier  36 , thereby creating wireless signals that are transmitted from coil  28  to coil  22  of device  12 . Because data signals are conveyed wirelessly from device  24  to device  12  using coils  22  and  28 , this type of data communications between device  24  and device  12  may sometimes be referred to as in-band communications. Device  12  may use data receiver  20  to demodulate the wireless signals from device  24  and thereby receive the data transmitted from device  24 . The transmitted data may be used to authenticate device  24  to device  12 , may be used to supply feedback or other control signals to device  12 , or may be used to convey other information. 
     When device  12  is in power transmission mode, control circuitry  16  may use a pulse-width modulation (PWM) scheme to modulate the AC drive signals that are being supplied to the output transistors coupled to coil  22  and thereby adjust how much power is being supplied to device  24 . Output transistors in the power transmission portion of control circuitry  16  may, for example, be modulated at an AC frequency of about 200 kHz (or other suitable frequency above or below 200 kHz such as a frequency of 100 kHz-300 kHz, at least 100 kHz, less than 300 kHz, etc.) to create an AC signal to drive coil  22 . As this AC signal passes through coil  22 , a corresponding wireless power signal (electromagnetic signal  26 ) is created and conveyed to coil  28  of device  24 . The duty cycle of the PWM AC drive signals may, if desired, be adjusted based on power transmission feedback information that is conveyed in band from data transmitter  34  to data receiver  20 . For example, device  12  can use information that has been transmitted back from device  24  to device  12  to increase or decrease the amount of transmitted power that device  12  is providing to device  24 . 
       FIG. 2  is a circuit diagram showing illustrative circuitry that may be used for a wireless power transmitting device and wireless power receiving device in system  10 . As shown in  FIG. 2 , wireless power transmitting device  12  may receive a DC voltage Vin across capacitor Cin from AC-DC converter  14  ( FIG. 1 ). Control circuitry  16  may produce control signals that are applied to gates  46  of transistors Q 1  and Q 2 . Gates  46  of transistors Q 1  and Q 2  may receive complementary signals so that the gate of Q 1  is high when the gate of Q 2  is low and vice versa. With one illustrative configuration, transistors Q 1  and Q 2  may be supplied with an AC signal at 200 kHz or other suitable frequency (e.g., at least 100 kHz, less than 300 kHz, etc.) that is modulated using pulse width modulation. Other suitable control signals may be applied to Q 1  and Q 2 , if desired. Transistors Q 1  and Q 2  may be characterized by an internal diode and drain-source capacitance (see, e.g., capacitances Cds 1  and Cds 2 ), as shown schematically in  FIG. 2 . 
     Transistors Q 1  and Q 2  are coupled in series between a positive voltage terminal (at power supply voltage Vin) and a ground power supply terminal. Coil  22  has a first terminal coupled to ground and a second terminal coupled by capacitor Ctx to a node between Q 1  and Q 2  at voltage Vsw. As the control signals are applied to gates  46  of output transistors Q 1  and Q 2 , the DC voltage Vin is converted into an AC current that passes through capacitor Ctx and coil  22  (of inductance Ltx). This produces corresponding wireless signal  26 , which is transmitted to device  24  and received by coil  28  (of inductance Lrx) in device  24 . 
     The received AC signal from coil  28  is conveyed through capacitor Crx to bridge circuit  40  of rectifier  36 . The transistors S 1  and S 2  of rectifier  36  may be operated in synchronous rectifier mode to rectify the received signal and thereby produce rectified DC signal (voltage) Vrect across capacitor Cout. In synchronous rectifier operation, control circuitry  30  senses the voltage at the drain of each transistor and uses the sense voltage as a trigger signal to actively turn on each transistor when appropriate. Synchronous rectifier operation may enhance rectification efficiency by eliminating power losses due to diode turn on voltages. 
     Capacitor Cout may hold the voltage Vrect that is generated by bridge circuit  40  of rectifier  36  across output terminals OUT. During normal operation, charger  44  can use the DC voltage Vrect to charge battery  42  and to supply power to system circuitry in device  24 . 
     When it is desired to transmit data from device  24  to device  12 , data transmitter  34  of control circuitry  30  (e.g., a switch coupled to ground and coupled by a capacitor to node N 1  or other suitable transmitter circuitry) may be modulated in accordance with the data being transmitted. For example, the switch in transmitter  34  may be pulsed one or more times for each transmitted data bit (e.g., for each “one” bit being transmitted from device  24  to device  12 ). The presence of a predetermined number of pulses (e.g., one pulse, two pulse, three pulses, etc.) may correspond to a “one bit” and the absence of this number of pulses from transmitter  34  in the transmitted data stream may correspond to “zero” bits (as an example). Each pulse from transmitter  34  may be sufficiently short to induce signal ringing in coil  22 . For example, transmitter  34  may generate pulses of 1 microsecond in duration, pulses that are at least 0.1 ms long, pulses that are shorter than 10 ms, and/or other suitable pulses. Control circuitry  16  of device  12  may pause power transmission operations during the transmission of in-band data from device  24  to device  12  and may use data receiver  20  to receive the transmitted data from transmitter  34  (e.g., signals that are conveyed wirelessly from coil  28  to coil  22  via electromagnetic signals). 
     Any suitable modulation scheme may be used to support transmission of data to device  12 . With one illustrative configuration, transmitter  34  may transmit data to device  12  by applying sets of one or more drive signal pulses to the switch of transmitter  34  to coupled node N 1  to ground (e.g., through the capacitor in transmitter circuit  34 ). Each time control circuitry  30  applies one of these signal pulses to coil  28 , coil  28  will via electromagnetic coupling as signal  26  create a corresponding pulse in the current through coil  22  and due to the network of Ctx and Ltx and Cds 2 , current through coil  22  will ring and Vsw will ring as shown in  FIG. 3 . Using this arrangement, data may be transmitted from device  24  to device  12  in binary (one bits and zero bits). One bits may be represented by sets of one or more pulses (e.g., microsecond pulses) applied to coil  28  by data transmitter  34  using transistors S 1  and S 2 , by using a switch (e.g., a transistor) coupled to ground, or using other transmitter circuitry. Zero bits may be represented by the absence of these pulses in the transmitted binary data. Data receiver  20  may use a voltage sensor to monitor the voltage Vsw across capacitor Ctx, which corresponds to the received version of the transmitted signal. By monitoring voltage Vsw, receiver  20  may receive the data transmitted by data transmitter  34 . 
     If desired, data may also be transmitted from device  12  to device  24 . For example, the PWM signal that is applied to transistors Q 1  and Q 2  may be modulated by transmitter  18  using a modulation scheme such as frequency shift keying (FSK) or other suitable modulation scheme. Data receiver  32  may have a detector circuit that is coupled across capacitor Crx to detect the modulated data signal from transmitter  18 . Data transmission from device  12  to device  24  may take place during power transmission from device  12  to device  24 . During data transmission from device  24  to device  12 , coil  22  may be used to receive data rather than to wirelessly transmit power. 
       FIG. 3  is a graph showing signals involved in using device  12  to transmit power to device  24  (during period T 1 ) and in using device  24  to transmit data to device  12  (during period T 2 ). During period T 1 , control circuitry  16  modulates output transistors Q 1  and Q 2  to produce wireless signals  26  from coil  22  (see, e.g., signal Q 1 _gate, which is an illustrative signal of the type that may be applied to gate  46  of Q 1 ). Period T 1  may be, as an example, 5-20 ms in duration, more than 5 ms, less than 20 ms, or other suitable time period. During power transmission in period T 1 , transmitter circuit  18  may modulate the frequency of the signal applied to transistors Q 1  and Q 2  (e.g., to transmit FSK data to device  24 ). The FSK data may include a request for device  24  to respond (e.g., to provide an identifier, to provide charging parameters, etc.). 
     The power transmitted by coil  22  to coil  28  during period T 1  is stored in capacitor Cout. As shown in  FIG. 3 , the DC voltage Vrect that is produced by rectifier  36  and that is stored across Cout ramps up during period T 1 . Voltage Vrect will increase in this way and energy will be stored in capacitor Cout even in the absence of stored energy in battery  42 , allowing device  24  to transmit data to device  12  even if battery  42  is empty. Charger  44  may disconnect battery  42  during the ramping up of voltage Vrect. 
     After sufficient energy has been stored in capacitor Cout to power control circuitry  30 , control circuitry  16  may cease modulation of transistors Q 1  and Q 2  and data transmitter  34  may begin transmitting data to data receiver  20 . Data transmitter  34  may, for example, modulate the voltage at node N 1 . The output signal supplied to node N 1  (V N1 ) may have a set of pulses (e.g., three pulses in the example of  FIG. 3 ) for each one bit and may be have an absence of pulses for each zero bit. In the illustrative configuration of  FIG. 2 , transmitter circuit  34  has a switch coupled to node N 1  for modulating the signal on node N 1 . If desired, transmitter  34  may modulate the signal transmitted through coil  28  by applying pulses to the gate of transistor S 1  and/or transistor S 2  (as an example). 
     Each pulse from transmitter  34  induces ringing in the current flowing through coil  28 . This ringing AC current produces AC wireless signals  26  that are received by coil  22  and converted into a ringing voltage Vsw in device  12 . Data receiver  20  may monitor the signal Vsw and may demodulate Vsw to produce received data Dem_Code, as indicated by the bottom trace in the graph of  FIG. 3 . 
     A flow chart of illustrative operations involved in using system  10  to transmit power from device  12  to device  24  and to communicate data between devices  24  and  12  is shown in  FIG. 4 . 
     During the operations of block  50 , a user of device  24  may bring device  24  into the vicinity of device  12 . Device  12  may detect the presence of device  24  wirelessly (e.g., by making wireless impedance measurements, using a light-based proximity sensor, using a capacitive proximity sensor, or using other circuitry) or a user may activate a switch or other input device that informs device  12  that device  24  is available to receive wireless power. 
     During the operations of block  52 , device  12  may transmit wireless power to device  24 . The operations of block  52  may be initiated in response to user input to device  12  or in response detecting that device  24  is ready to receive wireless power using the sensor measurements or other measurements of block  50 . For example, the operations of block  52  may be initiated by device  12  periodically (e.g., once per minute or other suitable time period), may be initiated in accordance with a predetermined schedule, or may be initiated in response to satisfaction of predetermined wireless power transmission initiation criteria. Wireless power may be transmitted from device  12  to device  24  by using control circuitry  16  to modulate transistors Q 1  and Q 2  to produce an AC drive signal through coil  22  and thereby produce a corresponding wireless signal  26  that is received by coil  28  in device  24 . The power transmission operations of block  52  may last sufficiently long to charge up capacitor Cout to a level that allows the energy in capacitor Cout to power control circuitry  30 , as illustrated by the ramped voltage Vrect in  FIG. 3 . During the operations of block  52 , device  12  may send an FSK request to device  24  (e.g., a request that asks device  24  to supply a device identifier, charging parameters, and/or other information). 
     After device  12  energizes capacitor Cout and control circuitry  30  of device  24  in this way, device  12  may cease transmitting wireless power to device  24  (e.g., for a waiting period of about 20 ms, at least 5 ms, less than 50 ms, etc.) to allow device  24  to process the received FSK request and to allow device  24  to begin transmitting data to device  12  in response to the received request (block  54 ). While power transmission is stopped in this way and data is being transmitted to device  12 , display  29  may display images uninterruptedly and/or other electrical components in device  24  may operate without interruption (e.g., without interruption from power loss). During the operations of block  54 , data transmitter  34  of circuitry  30  may modulate the voltage V N1  on node N 1  using a switch coupled to ground and/or by modulating transistors S 1  and S 2  or other transmitter circuitry in device  24  (e.g., to produce sets of pulses of the type shown in  FIG. 3 ) in accordance with the binary data stream being transmitted to device  12 . During the operations of block  56 , data receiver  20  may demodulate signal Vsw in device  12  (e.g., by using a zero-crossing detector to count zero transitions in the ringing signal Vsw or by otherwise detecting the ringing pulses induced by the pulses in V N1  created by transmitter circuit  34  in device  24 ) and thereby receive the transmitted data stream. In general, any suitable data modulation scheme may be used in transmitting data from device  24  to device  12  using transistors S 1  and S 2  in bridge circuit  40  of rectifier  36 . The illustrative configuration of  FIG. 3  in which each set of three pulses applied to the gates of transistors S 1  and S 2  corresponds to a one bit and in which each comparable time period without pulses corresponds to a data zero bit is presented as an example. 
     Data transmission from device  24  to device  12  may be used to supply device  24  with feedback (e.g., information that directs device  24  to adjust its PWM output signal to increase or decrease the amount of wireless power being transmitted from device  12  to device  24 ), may be used to authenticate device  24  to device  12  (e.g., when device  24  is initially brought into the vicinity of device  12 ), or may be used to take other suitable action (block  58 ). 
     If desired, the operations of  FIG. 4  may take place continuously or nearly continuously. For example, following authentication or power transmission level adjustments during the operations of block  58 , processing may loop back to the operations of block  52 , so that device  12  can repower device  24  and so that additional data may be transmitted from device  24  to device  12 . 
       FIG. 5  shows illustrative signals  60  associated with transmitting data from transmitter  34  to receiver  20 . The uppermost trace of  FIG. 5  corresponds to the ring-inducing pulses applied to node N 1  of device  24  to node N 1 . There are three pulses per transmitted data bit (e.g., per “one” bit) in the present example, but fewer pulses or more pulses from transmitter  34  may be associated with each bit. Pulses in V N1  produce corresponding current pulses in current I Lrx  (the middle trace of  FIG. 5 ) through coil  28  and result in ringing decaying pulses in Vsw (the lowermost trace in  FIG. 5 ) in device  12  that are detected by receiver  20  in device  12  (e.g., each current pulse through coil  28  induces a corresponding ringing current pulse through coil  22  that is detected by receiver circuit  20 ). 
     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: 20170601
Publication Date: 20200331
Grant Date: 20200331
Priority Date: 20160628
Inventors: DAYAL, ROHAN
QIU, WEIHONG
MOUSSAOUI, ZAKI
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J7/00034", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/3827", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3827", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3827", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/00034", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02M3/135", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 60677938