PATENT DOCUMENT

Publication Number: US-11133696-B2
Application Number: US-201916424331-A
Country: US
Kind Code: B2

Title: Wireless power system

Abstract:
A battery case has first and second coils on opposing sides of a battery and has switching circuitry that is coupled between the first and second coils. The battery case has a battery that provides supplemental battery power wirelessly to a wireless power receiving device via the second coil when the switching circuitry is in an open state. The case can also receive power wirelessly with the first coil from a wireless charging mat when the switching circuitry is in the open state. In a closed state, the switching circuitry shorts the first and second coils together so that current flowing through the first coil flows through the second coil in series and so that wireless power from the wireless charging mat that is received with the first coil is transmitted wirelessly to the wireless power receiving device using the second coil.

Claims:
What is claimed is: 
     
       1. A battery case that is operable in a system having a wireless power transmitting device and having a wireless power receiving device that is removably attached to the battery case, comprising:
 a battery; 
 a first coil; 
 a second coil; 
 switching circuitry coupled between the first and second coils; and 
 control circuitry configured to selectively place the switching circuitry in (1) an open state and (2) a closed state, wherein in the closed state the first and second coils are shorted together, power is received wirelessly by the first coil from the wireless power transmitting device and induces a given current to flow through the first coil and causes the given current to flow through the second coil, and the second coil provides the power wirelessly to the wireless power receiving device and in the open state power is received wirelessly by the second coil from the wireless power receiving device to charge the battery. 
 
     
     
       2. The battery case of  claim 1  wherein the control circuitry is configured to place the switching circuitry in the open state while using the first coil to wirelessly receive power from the wireless power transmitting device to charge the battery. 
     
     
       3. The battery case of  claim 2  wherein the control circuitry is configured to place the switching circuitry in the open state while using the second coil to wirelessly transmit power from the battery, through the second coil to the wireless power receiving device. 
     
     
       4. The battery case of  claim 1  wherein the first coil has first and second terminals, the second coil has first and second terminals, and the switching circuitry includes:
 a first switch with a first terminal connected to the first terminal of the first coil and a second terminal connected to the first terminal of the second coil; and 
 a second switch with a first terminal connected to the second terminal of the first coil and a second terminal connected to the second terminal of the second coil. 
 
     
     
       5. The battery case of  claim 1  wherein, in the closed state, the switching circuitry shorts a first terminal of the first coil to a first terminal of the second coil and shorts a second terminal of the first coil to a second terminal of the second coil so that the given current flows in series through the first and second coils. 
     
     
       6. The battery case of  claim 1  further comprising:
 a housing that surrounds the battery, wherein the first coil is located in the housing on a first side of the battery and the second coil is located in the housing on an opposing second side of the battery. 
 
     
     
       7. The battery case of  claim 6  wherein the wireless power receiving device comprises a cellular telephone and wherein the housing is configured to receive the cellular telephone. 
     
     
       8. The battery case of  claim 7  wherein the second coil is interposed between the battery and the cellular telephone when the cellular telephone is received within the housing. 
     
     
       9. The battery case of  claim 1  wherein the control circuitry is configured to place the switching circuitry in the open state to prevent current from flowing through the first and second coils in series. 
     
     
       10. The battery case of  claim 1  wherein the control circuitry is configured to place the switching circuitry in the open state while using the second coil to wirelessly transmit power from the battery to the wireless power receiving device. 
     
     
       11. The battery case of  claim 1  wherein while the switching circuitry is in the open state, the control circuitry is configured to operate in:
 a first mode in which the control circuitry uses the first coil to wirelessly receive power; and 
 a second mode in which the control circuitry uses the second coil to wirelessly transmit power. 
 
     
     
       12. An electronic device comprising:
 a first coil having first and second terminals; 
 a second coil having third and fourth terminals; 
 switching circuitry selectively configured to operate in (1) a first mode in which the first and second coils are shorted together and a current that flows through the first coil also flows through the second coil and (2) a second mode in which the first and second coils are electrically isolated so that no shared current flows through both the first and second coils, wherein the switching circuitry includes a first switch with a first switch terminal connected to the first terminal and a second switch terminal connected to the third terminal and the switching circuitry includes a second switch with a third switch terminal connected to the second terminal and a fourth switch terminal connected to the fourth terminal; 
 a battery; and 
 rectifier circuitry coupled to the first coil and configured to use the first coil to receive wireless power in the second mode to charge the battery. 
 
     
     
       13. The electronic device of  claim 12  further comprising:
 an inverter configured to use the second coil to transmit power wirelessly in the second mode. 
 
     
     
       14. The electronic device of  claim 13  wherein the first coil is configured to receive wireless power in the first mode that induces the current flowing through the first and second coils and wherein the second coil is configured to transmit wireless power in the first mode as the current flows through the second coil. 
     
     
       15. The electronic device of  claim 14  further comprising a battery case housing surrounding the battery, the first and second coils, the switching circuitry, the rectifier circuitry, and the inverter. 
     
     
       16. A cellular telephone battery case configured to removably attach to a cellular telephone and operable with a wireless charging device, the cellular telephone battery case comprising:
 a battery; 
 a first coil; 
 a second coil, wherein the battery is interposed between the first coil and second coil; 
 switching circuitry coupled between the first and second coils; and 
 rectifier circuitry configured to charge the battery with wireless power received by the first coil from the wireless charging device when the switching circuitry is in an open state, wherein, when the switching circuitry is in a closed state and the cellular telephone is attached, the first coil is configured to receive wireless power from the wireless charging device and the second coil is shorted to the first coil and is configured to transmit wireless power to the cellular telephone that has been received by the first coil from the wireless charging device. 
 
     
     
       17. The cellular telephone battery case of  claim 16  further comprising wireless power transmitter circuitry coupled to the second coil and configured to transmit power wirelessly to the cellular telephone using the second coil when the switching circuitry is in the open state. 
     
     
       18. The cellular telephone battery case of  claim 16  further comprising:
 a status indicator light configured to display battery charge status information corresponding to a battery charge level. 
 
     
     
       19. The cellular telephone battery case of  claim 18  further comprising:
 circuitry that communicates wirelessly with the cellular telephone to obtain information on the battery charge level from the cellular telephone using the second coil. 
 
     
     
       20. The cellular telephone battery case of  claim 16  further comprising:
 in-band communications circuitry coupled to at least one of the first and second coils.

Description:
This application claims the benefit of provisional patent application No. 62/791,587, filed Jan. 11, 2019, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to power systems, and, more particularly, to wireless power systems. 
     BACKGROUND 
     In a wireless charging system, a wireless charging mat wirelessly transmits power to a portable electronic device that is placed on the mat. The portable electronic device has a coil and rectifier circuitry. The coil receives alternating-current wireless power signals from a coil in the wireless charging mat that is overlapped by the coil in the portable electronic device. The rectifier circuitry converts the received signals into direct-current power. 
     SUMMARY 
     A wireless power system has a wireless charging device such as a wireless charging mat or other wireless power transmitting device. Battery-powered electronic devices such as cellular telephones, watches, and accessories are wirelessly charged when placed on a charging surface of the wireless charging mat. 
     A battery case is provided for a battery-powered electronic device such as a cellular telephone. The battery case is removably attached to the cellular telephone. When the cellular telephone is used for extended periods of time, a battery in the battery case provides supplemental power for the cellular telephone. 
     The battery case is wirelessly charged when placed on the wireless charging mat. In some configurations, a cellular telephone with an attached battery case is placed on the wireless charging mat. To efficiently charge the cellular telephone from the mat in this situation, the battery case that is attached to the cellular telephone has circuitry that is operable in a bypass mode. 
     The battery case has first and second coils mounted in a housing. The housing has first and second opposing faces. The first face is formed by a portion of the housing that faces the charging surface. The second face is formed by a portion of the housing that faces the cellular telephone. The battery of the battery case is enclosed within the housing so that the first coil is located between the first face and the battery and so that the second coil is located between the second coil and the battery. 
     Switching circuitry such as a pair of switches is coupled between the first and second coils. In an open state, the switching circuitry electrically isolates the first and second coils, so that current flowing in one of the coils does not flow through the second coil via the switches. In a closed state, the switching circuitry shorts the first and second coils together. In the closed state, current flowing through the first coil also flows in series through the second coil. 
     The case can receive power wirelessly with the first coil from the wireless charging mat when the switching circuitry is in the open state. This received power can be used to charge the battery in the case. If desired, the switching circuitry can be placed in the open state to allow wireless power transmitting circuitry in the case to transmit power wirelessly to the cellular telephone using the second coil. In a closed state, the switching circuitry shorts the first and second coils together so that power from the wireless charging mat bypasses the battery and charges the cellular telephone. In the closed state, the first coil receives wireless power signals from the wireless charging mat and a corresponding current is induced in the first coil. This current flows through the second coil, which transmits corresponding wireless power signals to the cellular telephone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative wireless power system in accordance with an embodiment. 
         FIG. 2  is a circuit diagram of illustrative wireless power circuitry in accordance with an embodiment. 
         FIG. 3  is a schematic diagram of illustrative electronic device circuitry in accordance with an embodiment. 
         FIG. 4  is a circuit diagram of an illustrative wireless power system in accordance with an embodiment. 
         FIG. 5  is a diagram of illustrative operations involved in using a wireless power system in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A wireless power system includes electronic devices that convey wireless power. An exploded side view of an illustrative wireless power system (wireless charging system) is shown in  FIG. 1 . As shown in  FIG. 1 , wireless power system  8  includes electronic devices  10 . Each electronic device  10  may include control circuitry and wireless power circuitry. The electronic devices may also have additional components such as input-output devices, batteries, and/or other circuitry. 
     Devices  10  may be any suitable electronic devices such as power adapters, wristwatches, cellular telephones or other handheld devices, laptop computers, tablet computers, accessories such as earbuds, electronic pencils (e.g., a stylus), or computer mice, other portable electronic devices, and/or other electronic equipment. In an illustrative configuration, which is sometimes described herein as an example, system  8  has a first electronic device  10 A, a second electronic device  10 B, and a third electronic device  10 C. Electronic device  10 A is a wireless power transmitting device such as a wireless charging mat. Device  10 A has a housing such as housing  22 A (e.g., a housing with a planar upper charging surface on which devices to be charged are placed). Electronic device  10 C is a portable electronic device such as a cellular telephone and electronic device  10 B is a battery case. Device  10 B has a housing such as housing  22 B with a recess R and/or other structures configured to receive housing  22 C of device  10 C. In this way, a user may removably attach device  10 C to device so that devices  10 B and  10 C may be used together as a portable unit. Housing  22 C may have planar front and rear faces (as an example). The front face, which faces upwardly in the orientation of  FIG. 1 , has a display. The rear face of housing  22 C faces towards housing  22 B of device  10 B. 
     To provide device  10 C with supplemental power while protecting device  10 C from damage due to stress-producing events such as drop events, device  10 B is installed on device  10 C (e.g., housing  22 C of device  10 C is placed within corresponding recess R in housing  22 B of device  10 B). In this position, devices  10 B and  10 C may be carried in the pocket of a user (as an example). When it is desired to receive wireless power from device  10 A, devices  10 B and  10 C may be placed together on the charging surface of device  10 C. 
     Device  10 A has one or more wireless power coils such as wireless power coil  12 . Coils such as coil  12  are used for inductive wireless power transfer and may therefore sometimes be referred to as inductive power coils. When it is desired to transmit wireless power, an alternating current is applied to coil  12 , which generates a corresponding alternating-current electromagnetic field. Wireless power that is transmitted in this way is received by corresponding nearby wireless power coils. As shown in  FIG. 1 , for example, device  10 C has at least one wireless power coil such as coil  20  that can receive wireless power directly from coil  12  in the absence of device  10 B. Device  10 B has two wireless power coils such as coils  14  and  16 . 
     During a bypass mode of operation, coils  14  and  16  are shorted together. While shorted together, alternating current electromagnetic signals that are transmitted by coil  12  are received by coil  14 . Coil  16  is shorted to coil  14  in this mode of operation, so coil  16  emits electromagnetic signals that are received by coil  20  in device  10 C. Electrical components such as battery  18  may be interposed between coils  14  and  16 . In the absence of the shorting path between coils  14  and  16 , wireless power signals may tend to be blocked by the presence of battery  18 . When coils  14  and  16  are shorted together, however, the wireless power that is received by coil  14  is reemitted as transmitted wireless power signals by coil  16  for reception by coil  20 . As a result, the shorting of coils  14  and  16  allows internal device components such as battery  18  to be effectively bypassed. This helps prevent components in device  10 B such as battery  18  from blocking the transfer of power from device  10 A to device  10 B. As used herein, the shorting of coils  14  and  16  refers to the connection of a first lead from each of coils  14  and  16  together and a second lead from each of coils  14  and  16  together. One or more switches connected in series with coils  14  and  16  can selectively short the two coils. When shorted together, wireless power received by coil  14  induces a given current to flow through coil  14  that flows in series through coil  16  (e.g., an alternating-current signal flows in a loop through coils  14  and  16 ). In effect, shorting coils  14  and  16  together forms a unitary two-part coil structure. In the bypass mode, the first part of the two-part coil structure receives alternating-current electromagnetic fields and causes an alternating-current (AC) current to flow through the first and second parts in series. While the AC current is flowing through the second part, electromagnetic fields are emitted by the second part that are received by wireless power receiving device  10 C. 
     Housing  22 B of device  10 B may have opposing planar surfaces. A first face of the housing of device  10 B may face the upper charging surface of device  10 A when device  10 B is placed on device  10 A for charging. The opposing second face of the housing of device  10 B may face the lower surface of housing  22 C when device  10 C is attached to device  10 B. Battery  18  may have a planar shape (as an example). As shown in  FIG. 1 , battery  18  lies between the opposing first and second faces of housing  22 B of device  10 B. Coil  14  is located between battery  18  and the first face of housing  22 B (facing device  10 A). Coil  16  is located between battery  18  and the second face of housing  22 B (facing device  10 C). In this embodiment, battery  18  is interposed between coils  14  and  16 . 
     The devices  10  of  FIG. 1  may transmit power and/or may receive wireless power. Illustrative wireless power circuitry of the type that may be used in devices  10  is shown in  FIG. 2 . The wireless power circuitry of  FIG. 2  includes wireless power transmitter TX and wireless power receiver circuitry RX. During operation, wireless power signals  44  are transmitted by circuitry TX and received by circuitry RX. In the embodiment of  FIG. 2 , wireless power is transferred from coil  36  to coil  82  in a single direction. If desired, additional transmitter and receiver circuitry may be provided to allow wireless power to be transferred bidirectionally (e.g., to allow a first transmitter circuit to transmit power from coil  36  to coil  82  for reception by a first receiver circuit and to also allow a second transmitter circuit to transmit power from coil  82  to coil  36  for reception by a second receiver circuit). The unidirectional power transmission circuitry of  FIG. 2  is illustrative. 
     As shown in  FIG. 2 , circuitry TX includes inverter circuitry  80 . Control circuitry supplies control signals to inverter circuitry  80 . Inverter circuitry  80  supplies corresponding alternating-current drive signals to coil  36 . Circuit components such as capacitor  70  may be coupled in series with coil  36  as shown in  FIG. 2 . When alternating-current current signals are supplied to coil  36 , corresponding alternating-current electromagnetic signals (wireless power signals  44 ) are transmitted to nearby coils such as illustrative coil  82  in receiver circuitry RX. This induces a corresponding alternating-current (AC) current signal in coil  82 . Capacitors such as capacitors  72  may be coupled in series with coil  82 . Rectifier  50  receives the AC current from coil  82  and produces corresponding direct-current power (e.g., direct-current voltage Vrect) at output terminals  76 . This power may be used to power a load. 
     In a bidirectional wireless power system, wireless power transmitting circuitry such as inverter  80  and wireless power receiving circuitry such as receiver  50  may be coupled to a common coil. This allows the same coil to be used in receive wireless power (when the wireless power receiving circuitry is active) and in transmitting wireless power (when the wireless power transmitting circuitry is active). Arrangements in which a pair of coils (see, e.g., coils  14  and  16 ) are selectively coupled together with switching circuitry may also be used. The circuitry of  FIG. 2  may be used in device  10 A,  10 B, and/or  10 C (e.g., coils  36  and/or  82  may be implemented using coils such as coils  12 ,  14 ,  16 , and/or  20  of  FIG. 1 ). 
       FIG. 3  is a schematic diagram showing illustrative circuitry that may be used in each device  10  in system  8 . The circuitry of  FIG. 3  need not all be used in a given device. For example, some of the circuitry of device  10  of  FIG. 3  may be used in device  10 A but not in devices  10 B and  10 C. Device  10 A may, as an example, be a wireless charging mat that is coupled by a cable to a mains power supply (e.g., a wall outlet). In this arrangement, device  10 A may use an alternating-current-to-direct-current power converter such as AC-DC converter  90  to convert alternating-current (AC) mains power to direct-current (DC) power for use by device  10 A, whereas circuitry such as AC-DC converter  90  may be omitted from devices  10 B and  10 C. If desired, device  10 A and/or devices  10 B and  10 C may include other types of power sources. For example, device  10 A, device  10 B, and/or device  10 C may include batteries such as battery  92 . 
     Devices  10 A,  10 B, and  10 C may include wireless power circuitry  96  such as wireless power transmitter circuitry TX and/or wireless power receiver circuitry RX. For example, device  10 A may contain only transmitter circuitry TX and no receiver circuitry RX. Device  10 C may contain only receiver circuitry RX for receiving power from device  10 A and/or from device  10 B or, if desired, may contain both receiver circuitry RX (for receiving power from device  10 A and/or device  10 B) and transmitter circuitry TX (for transmitting power to an electronic device  10  such as a pair of earbuds, an electronic stylus, or other electronic device and/or for transmitting power to device  10 B). Device  10 B may contain circuitry RX (e.g., to receive power from device  10 A to charge a battery in device  10 B and, if desired, to receive power from device  10 C) and may contain circuitry TX (e.g., to transmit power from the battery in device  10 B to device  10 C when devices  10 B and  10 C are coupled together and device  10 C desires supplemental power from device  10 B and/or to transmit power from the battery in device  10 B to other electronic devices). Other configurations (e.g., configurations in which device  10 A includes wireless power receiver circuitry RX, etc.) may also be used, if desired. Wireless power transmitter circuitry TX and wireless power receiver circuitry RX contain coils, as described in connection with coils  36  and  82  of  FIG. 2 . 
     Device  10 A, device  10 B, and device  10 C include control circuitry as shown by control circuitry  104  of device  10  of  FIG. 3 . Control circuitry  104  is used to control the operation of devices  10 A,  10 B, and  10 C. This control circuitry may include 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 A,  10 B, and  10 C. For example, the processing circuitry may be used in selecting coils, determining power transmission levels, processing sensor data and other data, processing user input, handling negotiations between devices, sending and receiving in-band and out-of-band data, making measurements, and otherwise controlling the operation of system  8 . 
     Control circuitry in system  8  such as control circuitry  104  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  104 . 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  104 . 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. 
     Electronic devices  10 A,  10 B, and  10 C may include input-output circuitry as shown by input-output devices  94  of  FIG. 3 . Input-output devices  94  may include light-based devices (e.g., displays, status indicator lights formed from light-emitting diodes or other light emitters, ambient light sensors, image sensors, optical proximity sensors, three-dimensional image sensors formed from light emitters that project beams of light and corresponding image sensors that detect dots where the projected light beams strike objects, camera flash components, and/or other circuits that emit and/or detect light), radio-frequency circuitry (e.g., radio-frequency circuitry such as radar circuitry and/or other radio-frequency circuitry for detecting the location and movement of objects), acoustic components (e.g., microphones for gathering sound and speakers for emitting sound), haptic output devices for providing vibrations and other haptic output, touch sensors, buttons, force sensors, joysticks, knobs, temperature sensors, gas sensors, and/or other circuitry for detecting user input and for measuring environmental data. 
     Electronic devices  10 A,  10 B, and  10 C may be any suitable electronic devices. For example, device  10 A 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 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 device  10 A is a wireless power transmitting device such as a wireless charging mat are sometimes described herein as an example. Electronic device  10 B may be a supplemental battery pack. For example, device  10 B may include a battery such as battery  92  to provide supplemental battery power to electronic devices such as device  10 C and/or other electronic devices. Illustrative configurations in which device  10 B is a battery case (sometimes referred to as a supplemental enclosure, removable case, or removable battery case) are sometimes described herein as an example. Electronic device  10 C may be a cellular telephone or other portable electronic device (e.g., a tablet computer, laptop computer, wristwatch device, headphones, earbuds, stylus, or other electronic device). Illustrative configurations in which device  10 C is a cellular telephone are sometimes described herein as an example. 
     Devices  10 A,  10 B, and/or  10 C may include wireless communications circuitry such as communications circuitry  102  of device  10  of  FIG. 3 . The wireless communications circuitry may be used by devices  10 A,  10 B, and/or  10 C to allow these devices (or a subset of these devices) to communicate wirelessly using in-band or out-of-band communications. Circuitry  102  may, for example, have wireless transceiver circuitry (e.g., a wireless transmitter) that wirelessly transmits out-of-band signals to an external device using an antenna. Circuitry  102  may also have wireless transceiver circuitry (e.g., a wireless receiver) that is used to wirelessly receive out-of-band signals from an external device using the antenna. 
     Wireless communications circuitry  102  can use one or more coils (e.g., coils in transmitter circuitry TX and/or receiver circuitry RX) to transmit and/or receive in-band signals. Any suitable modulation scheme may be used to support in-band communications between devices  10 A,  10 B, and/or  10 C. With one illustrative configuration, frequency-shift keying (FSK) is used to convey in-band data from a power transmitting circuit to a power receiving circuit (e.g., the frequency of wireless power signals may be modulated when power is being transmitted from the power transmitting circuit to the power receiving circuit) and amplitude-shift keying (ASK) is used to convey in-band data from a wireless power receiving circuit to a wireless power transmitting circuit. Power may be conveyed wirelessly between devices during these FSK and ASK transmissions. Other types of in-band communications may be used, if desired. 
     During wireless power transmission operations, control circuitry  104  drives inverter circuitry in transmitter circuitry TX to supply AC drive signals to one or more coils at a given power transmission frequency. The power transmission frequency may be, for example, a predetermined frequency of about 125 kHz, at least 80 kHz, at least 100 kHz, less than 500 kHz, less than 300 kHz, or other suitable wireless power frequency. In some configurations, the power transmission frequency may be negotiated in communications between devices. In other configurations, the power transmission frequency may be fixed. 
     During wireless power transfer operations with a wireless power transmitting device (e.g., one of devices  10  in system  8 ), while power transmitter circuitry TX is driving AC signals into one or more of coils to produce wireless signals  44  at the power transmission frequency, communications circuitry  102  uses FSK modulation to modulate the power transmission frequency of the driving AC signals and thereby modulate the frequency of signals  44 . In a wireless power receiving device (e.g., another of devices  10  in system  8 ), a coil is used to receive signals  44 . Power receiver circuitry RX uses the received signals on the coil and the rectifier circuitry in circuitry RX to produce DC power. At the same time, wireless transceiver circuitry in the receiving device uses FSK demodulation to extract the transmitted in-band data from signals  44 . This approach allows FSK data (e.g., FSK data packets) to be transmitted in-band between devices  10  with coils while power is simultaneously being wirelessly conveyed from between devices  10  using the coils. 
     In-band communications between devices  10  may also use ASK modulation and demodulation techniques. Wireless transceiver circuitry in a wireless power receiving device (e.g., one of devices  10 ) transmits in-band data to a wireless power transmitting device (e.g., another of devices  10 ) by using a switch (e.g., one or more transistors that are coupled to a wireless power receiver coil) to modulate the impedance of the power receiver circuitry RX of the wireless power receiving device. This, in turn, modulates the amplitude of signal  44  and the amplitude of the AC signal passing through the transmitting coil(s). Wireless transceiver circuitry in a wireless power transmitting device monitors the amplitude of the AC signal passing through the wireless power transmitting coil(s) and, using ASK demodulation, extracts the transmitted in-band data from these signals that was transmitted by wireless transceiver circuitry in the wireless communications circuitry of the wireless power receiving device. The use of ASK communications allows ASK data bits (e.g., ASK data packets) to be transmitted in-band from a power receiving device to a power transmitting device while power is simultaneously being wirelessly conveyed from the power transmitting device to the power receiving device. 
     If desired, control circuitry  104  of devices  10 A,  10 B, and/or  10 C (e.g., device  10  of  FIG. 3 ) may have external object measurement circuitry  100  (sometimes referred to as foreign object detection circuitry or external object detection circuitry) that detects external objects on a charging surface or other wireless power output region associated with device  10 . Circuitry  100  can detect foreign objects such as coils, paper clips, and other metallic objects and can detect the presence of a wireless power receiving device in the vicinity of wireless power transmitting circuitry. During object detection and characterization operations, external object measurement circuitry  100  can be used to make measurements on coils in device  10  to determine whether any external electronic devices are present on or near device  10  (e.g., touching a surface of the housing of device  10 ). 
     In an illustrative arrangement, measurement circuitry  100  of control circuitry  104  contains signal generator circuitry (e.g., oscillator circuitry for generating AC probe signals at one or more probe frequencies, a pulse generator, etc.) and signal detection circuitry (e.g., filters, analog-to-digital converters, impulse response measurement circuits, etc.). The characteristics of the coil that receives a signal from measurement circuitry  100  depend on whether any foreign objects overlap that coil (e.g., coins, wireless power receiving devices, etc.) and also depend on whether a wireless power receiving device with a coil is present, which could increase the measured inductance of a coil. Signal measurement circuitry  100  is configured to apply signals to the coil and measure corresponding signal responses. For example, signal measurement circuitry  100  may apply an alternating-current probe signal while monitoring a resulting signal at a node coupled to the coil. As another example, signal measurement circuitry  100  may apply a pulse to the coil and measure a resulting impulse response (e.g., to measure coil inductance). Using measurements from measurement circuitry  100 , device  10  can determine whether an external object is present on the coil(s) of device  10 . 
     If desired, measurement circuitry  100  and/or other circuitry in device  10  of  FIG. 3  may be omitted from one or more of devices  10 A,  10 B, and/or  10 C to help reduce the cost and complexity of that device. For example, device  10 A may have a battery to help store energy or battery  92  may be omitted from device  10 A to reduce cost (e.g., in an embodiment in which device  10 A has AC-DC power converter  90  to receive mains power). Converter  90  may, if desired, be omitted from devices  10 B and  10 C to conserve space and reduce cost and complexity for those devices. In an embodiment, measurement circuitry  100  is included in device  10 A and is omitted from devices  10 B and  10 C. In an embodiment in which device  10 C has wireless power transmitter circuitry TX, device  10 C may include measurement circuitry  100 . In an embodiment in which device  10 C does not include wireless power transmitter circuitry TX, device  10 C need not include measurement circuitry  100  (as an example). 
     Communications circuitry  102  may likewise be incorporated and/or omitted from one or more of devices  10 A,  10 B, and/or  10 C. In some embodiments, a given one of devices  10 A,  10 B, and  10 C includes only transmitter circuitry TX or only receiver circuitry RX. If desired, one or more of devices  10 A,  10 B, and/or  10 C may include transmitter circuitry TX and receiver circuitry RX. 
       FIG. 4  is a circuit diagram showing how devices  10 A,  10 B, and  10 C may be used together in system  8 . In the embodiment illustrated in  FIG. 4 , devices  10 A and  10 B are electromagnetically coupled (e.g., coil  120  of device  10 A is electromagnetically coupled with coil  122  of device  10 B). Devices  10 B and  10 C are also electromagnetically coupled (e.g., coil  124  of device  10 B is electromagnetically coupled with coil  126  of device  10 C). In device  10 A, wireless power circuitry such as wireless power circuitry  96  of  FIG. 3  (e.g., wireless power transmitter circuitry TX) is coupled to coil  120  so that wireless power can be transmitted from coil  120  to device  10 B. The transmitted power is received by coil  122 . In device  10 C, wireless power circuitry such as wireless power circuitry  96  of  FIG. 3  (e.g., wireless power receiver circuitry RX and optionally wireless power transmitter circuitry TX) is coupled to coil  126 . When it is desired to transmit wireless power from device  10 B to device  10 C, coil  124  may be used to transmit wireless signals to coil  126 . A rectifier in wireless power receiver circuitry RX of device  10 C rectifies the received signals and produces DC power for the components of device  10 C. In embodiments in which device  10 B is not present, wireless power can be transmitted from coil  120  of device  10 A to coil  126  of device  10 C. Optional wireless power transmitter circuitry in device  10 C can also be used to transmit wireless power (e.g., to device  10 B and/or other electronic devices such as earbuds and other accessories). 
     As shown in  FIG. 4 , device  10 B has circuitry  130  (sometimes referred to as control circuitry or control and power circuitry). Circuitry  130  includes circuitry such as control circuitry (see, e.g., circuitry  104  of  FIG. 3 ), power circuitry (see, e.g., wireless power circuitry  96  and battery  92  of  FIG. 3 ), and optional input-output circuitry (see, e.g., input-output devices  94  of  FIG. 3 ). During operation, control circuitry  130  supplies control signals to switching circuitry  128  formed from one or more switches. Switching circuitry  128  is coupled between coils  122  and  124 . Switching circuitry  128  may include, for example, a first switch that is interposed between a first terminal of coil  122  and a first terminal of coil  124  and a second switch that is interposed between a second terminal of coil  122  and a second terminal of coil  124 . This arrangement allows a full-bridge rectifier topology to be used for the rectifier circuitry of circuitry  130 . If desired, the second switch may be omitted (e.g., the second terminal of coil  122  may be shorted to the second terminal of coil  124 ). 
     Switching circuitry  128  is controlled by control signals that circuitry  130  supplies to switching circuitry  128  via control port CP. Circuitry  130  also has port PP 1  and signal lines  140  that couple port PP 1  to coil  122  and port PP 2  and signal lines  142  that couple port PP 2  to coil  124 . 
     Illustrative modes of operation for system  8  of  FIG. 4  are shown in  FIG. 5 . The control circuitry of system  8  is used in determining when to transition between the modes of operation of  FIG. 5 . For example, control circuitry in device  10 B may determine when to open and close switching circuitry  128  and make other changes to the operation of device  10 B by monitoring whether device  10 B is coupled to device  10 C and/or when device  10 B is coupled to device  10 A. In an embodiment, device  10 B uses measurement circuitry  100  and optionally communications circuitry such as in-band communications circuitry or other circuitry to determine when the coils of device  10 B are electromagnetically coupled to coils in other devices. In the event that device  10 B detects a nearby device (e.g., device  10 C), device  10 B and device  10 C can communicate to determine whether power should be wirelessly transmitted from device  10 B to device  10 C, etc. Device  10 B can independently communicate with device  10 A and with device  10 C to determine a satisfactory mode of operation and/or can monitor communications between device  10 A and device  10 C. If device  10 B is removed from device  10 A (e.g., as detected by measurement circuitry  100  in device  10 A, device  10 B, and/or  10 C and/or communications circuitry), a reset operation may be performed (e.g., so that device  10 B can establish a communications link such as an in-band communications link with device  10 C). 
     During the operations of mode  134 , switching circuitry  128  is placed in an open state, thereby electrically isolating coils  122  and  124 . In this mode, any current flowing in coil  122  does not flow through coil  124  and any current flowing in coil  124  does not flow through coil  124 . With coil  122  isolated from coil  124 , coil  122  can receive wireless power from coil  120  that is passed to rectifier circuitry in circuitry  130  via lines  140  and port PP 1  and/or coil  124  can optionally receive wireless power from coil  126  that is passed to rectifier circuitry in circuitry  130  via lines  142  and port PP 2 . In an embodiment, device  10 A (e.g., a charging mat) supplies device  10 B (e.g., a battery case) with wireless power that is received using coil  122  and circuitry  130  and that is used to charge battery  132  (e.g., a supplemental battery mounted in the housing of the battery case). 
     During the operations of mode  136 , device  10 B (e.g., a battery case) is not receiving wireless power from device  10 A (e.g., a charging mat) and device  10 A need not be present (e.g., device  10 B and a cellular telephone or other device  10 C may be coupled together and may be carried in a user&#39;s pocket or may be otherwise located far from device  10 A). In this mode, device  10 B (e.g., the battery case) can use the stored energy in battery  132  to wirelessly charge device  10 C (e.g., the cellular telephone that is attached to device  10 B). During these operations, switching circuitry  128  is placed in an open state and wireless power is transmitted by wireless power transmitter circuitry TX in circuitry  130  and coil  124 . This wirelessly transmitted power is received by coil  126  and wireless power receiver circuitry RX that is coupled to coil  126  in device  10 C. 
     In some situations, device  10 C is physically coupled to device  10 B (e.g., a cellular telephone is installed in a battery case) and the telephone and case are resting on the charging surface of device  10 A (e.g., a charging mat). To efficiently provide power to device  10 C from device  10 A in this scenario, system  8  is operated in mode  138 . During the operations of mode  138 , which may sometimes be referred to as a pass-through mode or bypass mode, control circuitry in circuitry  130  of device  10 B places switching circuitry  128  in a closed state (e.g., the first and second switches of circuitry  128  are both closed, so that the first terminal of coil  122  is shorted to the first terminal of coil  124  and so that the second terminal of coil  122  is shorted to the second terminal of coil  124 ). With coils  122  and  124  shorted together in this way, current flows through coils  122  and  124  in series (e.g., the same current that is flowing through coil  122  also flows through coil  124 ). 
     During mode  138 , as wireless power is transmitted from coil  120  to coil  122 , a corresponding alternating current is induced in coil  122 . This alternating current flows through coil  124  because coil  124  is shorted to coil  122 . When the alternating current that is flowing through coil  122  flows through coil  124 , electromagnetic signals (e.g., wireless power) is transmitted from coil  124  to coil  126  and received by the wireless power receiver circuitry RX of device  10 C. 
     As illustrated by coils  14  and  16  on opposing sides of battery  18  in the example of  FIG. 1 , coils  122  and  124  of  FIG. 4  may be placed on opposing sides of battery  132 . This arrangement facilitates electromagnetic coupling between coil  120  of device  10 A and coil  122  of device  10 B and facilitates electromagnetic coupling between coil  124  of device  10 B and coil  126  of device  10 C. As a result, power that is transmitted by device  10 A is efficiently conveyed to device  10 C bypassing battery  132  and intermediate AC-DC conversion steps in device. 
     If desired, system  8  may be operated in reverse while switching circuitry  128  is in its closed state. For example, device  10 C may use a wireless power transmitter to transmit power from coil  126  to coil  124  while coils  122  and  124  are shorted together and a coil in an accessory or other device with a coil such as coil  120  may receive corresponding wireless power transmitted from coil  122 . This arrangement allows energy to be transferred from device  10 C to device  10 A or to another electronic device such as earbuds, an electronic stylus, headphones, and/or a computer mouse. 
     In an embodiment, circuitry  130  does not rectify or otherwise tap into the wireless power that is received by coil  122  or coil  124  when switching circuitry  128  is closed. In another embodiment, rectifier circuitry in circuitry  130  taps a portion of the power received by coil  122  (e.g., a portion of this received power is converted to DC power for use by circuitry  130  while power is being transferred from device  10 A to device  10 C in the bypass mode). Circuitry  130  may, for example, tap a portion of the receive power to use in charging battery  132  and/or to supply input-output circuitry or other load circuitry with power while device  10 A is supplying wireless power to device  10 C (e.g., to charge a battery in device  10 C). 
     The communications circuitry of device  10 B (e.g., FSK and/or ASK decoder circuitry or other in-band and/or out-of-band communications circuitry) can allow devices  10 A and  10 C to communicate without taking action (e.g., so that device  10 C can provide device  10 A with control signals to dynamically adjust the amount of power that device  10 A transmits to device  10 C while circuitry  128  is closed). For example, devices  10 A and  10 C can communicate directly using in-band communications such as ASK and/or FSK communications whenever switching circuitry  128  is in its closed state to allow signals to pass through the combined coil formed by joining coils  124  and  122  in series through switching circuitry  128 . 
     In an embodiment, the communications circuitry of device  10 B monitors communications traffic between device  10 A and device  10 C or otherwise communicates with devices  10 A and/or  10 C. Device  10 B may, as an example, gather information on the status of system  8  by monitoring communications between devices  10 A and  10 C and/or by querying device  10 A and/or  10 C for information. This information may include, for example, charge status information, information on whether device  10 A is transmitting a reduced amount of power to ensure that operating temperature limits or other constraints are satisfied, whether a potential fault is present or is not present, whether power is being transmitted or is not being transmitted, the amount of charge of one or more of the batteries in system  8  (e.g., low, medium, or high), and/or other information on the operational state of system  8 . This information may be presented to a user of system  8  using input-output devices in device  10 A, device  10 B, and/or device  10 C. 
     In an embodiment, device  10 B has input-output devices (status indicator lights such as light-emitting diodes, a display, a speaker, a vibrator or other haptic output device, other output components, etc.) and these input-output devices supply status information to the user. The status information may be provided as visual status information (e.g., a battery charge state or wireless charging status indicated by light-emitting diodes or other visual output device), as audible output (e.g., tones indicating whether system  8  is charging or batteries are fully or partially charged), as haptic output (e.g., a vibration indicating that battery charging has commenced or ceased, etc.), and/or may be provided as other suitable output to convey information on the operation of system  8  to the user. 
     The foregoing describes a wireless charging technology that uses in-band communications (e.g., ASK) to provide information such as states of charge, charging speeds, and so forth, to control power transfer. It is not necessary for personal information to be transmitted in order for embodiments of the present technology to operate. However, because communications technologies such as ASK communicate bitwise information, it is technically possible for implementers of the present technology to communicate information beyond that which is needed to carry out wireless power transmission. 
     To the extent that the present technology is leveraged to transmit information that may implicate privacy concerns, hardware and/or software elements can be provided for users to selectively block the use of, or access to, personal information data. For example, a user may be notified upon placement of their phone on a wireless charging mat that their personal information data will be accessed if they continue with the wireless charging session. 
     It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. Personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     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: 20190528
Publication Date: 20210928
Grant Date: 20210928
Priority Date: 20190111
Inventors: MEHTA, NARENDRA S.
TERRY, STEPHEN C.
DAYAL, ROHAN
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J50/502", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M50/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/80", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/425", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02E60/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/488", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/0048", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/005", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/502", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01F27/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M2220/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/46", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F38/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/425", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J50/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H02J7/025", "inventive": true, "first": true, "tree": "[]"}, {"code": "H02J50/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/24", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 71517820