Patent Description:
Conventional charging pads utilize induction to generate a magnetic field that is used to charge a device. Users have encountered numerous frustrating issues with these conventional charging pads, including having damage caused to objects that include magnetic strips and/or RFID chips (e.g., credits cards, security badges, passports, key fobs, and the like). Moreover, many of these conventional pads typically require placing the device to be charged at a specific position on the charging pad, and the device may not be moved to different positions on the pad, without interrupting or terminating the charging of the device. This results in a frustrating experience for many users as they may be unable to locate the device at the exact right position on the pad in which to start charging their device, and may further end up with damage to important objects that they use on a daily basis. <CIT> describes a resonant type transmission power supply device and resonant type transmission power supply system. <CIT> describes a resonant type transmission power supply device and resonant type transmission power supply system. <CIT> describes a wireless power near-field repeater system that includes metamaterial arrays to suppress far-field radiation and power loss. <CIT> describes an apparatus and method for data communication using wireless power.

In a first aspect, there is provided a method according to claim <NUM>. In further aspects, there are provided a non-transitory computer-readable storage medium according to claim <NUM> and a wireless power transmitter according to claim <NUM>.

Accordingly, there is a need for wireless charging systems (e.g., radio frequency (RF) charging pads) that address the problems identified above. To this end, an RF charging pad is described herein that is capable of detecting whether an authorized wireless power receiver is located on the pad, and whether any other objects (which are not wireless power receivers) are located on the pad. Such systems and methods of use thereof help to discover presence of objects on the pad in order to determine whether to proceed with delivery of wireless power or whether to forgo transmitting wireless power in order to avoid potentially damaging any of the detected objects. The pad is also able to identify authorized wireless power receivers and/or ignore one or more wireless power receivers that are not authorized to be charged or powered by the RF charging pad and, thereby, avoid power leeching and other drains on the system as a whole, while ensuring that authorized wireless power receivers always receive power.

In some instances, the RF charging pad transmits test power transmission signals and then receives reflected power back from one or more wireless power receivers or from one or more objects (which are not wireless power receivers) that are present on the RF charging pad. The reflected power can be collected and analyzed to identify signature signals and to thereby determine whether an authorized device is present and/or also whether an object other than a wireless power receiver is present (as is explained in more detail below). In some embodiments, the process for reflecting power works even if an authorized wireless power receiver has no power remaining (e.g., its battery is completely drained), as the wireless power receiver is able to harness energy from the test power transmission signals to create impedance changes at the receiver side, which then cause different amounts of reflected power to be detected at the RF charging pad (and within different power-transfer zones thereof), thereby allowing the receiver to convey data to the RF charging pad.

As mentioned above, such systems and methods could further manage power transfer control communication between the RF charging pad and one or more wireless power receivers with or without any data-communication capability. In some instances, the wireless power receiver may comprise an electronic device, circuitry for receiving and converting wireless power transmission signals, and a data-communication radio, and the electronic device's battery may have no charge (or power) remaining, so the device is unable to send a data-communication signal to the pad. In this scenario, a different technique is needed to detect whether the wireless power receiver is authorized to receive wireless power or not. In other instances, the wireless power receiver may comprise an electronic device and circuitry for receiving and converting wireless power transmission signals, and may not include any data-communication radio, and thus a technique is needed to be able to determine whether such receivers are authorized to receive wireless power from the pad. The various embodiments discussed herein provide techniques that solve these problems.

In the description that follows, references are made to an RF charging pad that includes various antenna zones. For the purposes of this description, power-transfer (or antenna) zones include one or more power-transferring elements (e.g., antennas such as a capacitive coupler) of the RF charging pad, and each power-transfer zone may be individually addressable by a controlling integrated circuit (e.g., RF power transmitter integrated circuit <NUM>, <FIG>) to allow for selective activation of each power-transfer zone in order to determine which power-transfer zone is able to most efficiently transfer wireless power to a receiver. The RF charging pad is also inter-changeably referred to herein as a near-field charging pad, or, more simply, as a charging pad.

Thus, wireless charging systems configured in accordance with the principles described herein are able to one or more operations including (<NUM>) identifying an authorized electronic device, (<NUM>) discovering any foreign object between the RF charging pad and the wireless power receivers, and/or (<NUM>) managing power transfer control communication between the RF charging pad and wireless power receivers with or without any data-communication capability, thereby providing numerous improvements and resolving numerous problems and limitations of conventional charging pads.

Note that the various embodiments described above can be combined with any other embodiments described herein. The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims, and they will be considered part of the invention as far as they fall within the scope of the appended claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not intended to circumscribe or limit the inventive subject matter.

So that the present disclosure can be understood in greater detail, a more particular description may be had by reference to the features of various embodiments, some of which are illustrated in the appended drawings. The appended drawings, however, merely illustrate pertinent features of the present disclosure and are therefore not to be considered limiting, for the description may admit to other effective features, as far as the resulting subject-matter falls within the scope of the invention as defined by the appended claims.

In accordance with common practice, the various features illustrated in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. In addition, some of the drawings may not depict all of the components of a given system, method or device. Finally, like reference numerals may be used to denote like features throughout the specification and figures.

However, it will be apparent to one of ordinary skill in the art that the various described embodiments may be practiced without these specific details, and they will be part of the invention as far ass they fall within the scope of the invention as defined by the appended claims.

<FIG> is a block diagram of an RF wireless power transmission system <NUM> in accordance with some embodiments. In some embodiments, the RF wireless power transmission system <NUM> includes a RF charging pad <NUM> (also referred to herein as a near-field (NF) charging pad <NUM> or RF charging pad <NUM>). In some embodiments, the RF charging pad <NUM> includes an RF power transmitter integrated circuit <NUM> (described in more detail below). In some embodiments, the RF charging pad <NUM> includes one or more communications components <NUM> (e.g., wireless communication components, such as WI-FI or BLUETOOTH radios), discussed in more detail below with reference to <FIG>. In some embodiments, the RF charging pad <NUM> also connects to one or more power amplifier units <NUM>-<NUM>,. <NUM>-n to control operation of the one or more power amplifier units when they drive external power-transfer elements (e.g., power-transfer elements <NUM>). In some embodiments, RF power is controlled and modulated at the RF charging pad <NUM> via switch circuitry as to enable the RF wireless power transmission system to send RF power to one or more wireless receiving devices via the TX antenna array <NUM>.

In some embodiments, the communication component(s) <NUM> enable communication between the RF charging pad <NUM> and one or more communication networks. In some embodiments, the communication component(s) <NUM> are capable of data communications using any of a variety of custom or standard wireless protocols (e.g., IEEE <NUM>. <NUM>, Wi-Fi, ZigBee, 6LoWPAN, Thread, Z-Wave, Bluetooth Smart, ISA100.11a, WirelessHART, MiWi, etc.) custom or standard wired protocols (e.g., Ethernet, HomePlug, etc.), and/or any other suitable communication protocol, including communication protocols not yet developed as of the filing date of this document.

In some instances, the communication component(s) <NUM> are not able to communicate with wireless power receivers for various reasons, e.g., because there is no power available for the communication component(s) to use for the transmission of data signals or because the wireless power receiver itself does not actually include any communication component of its own. As such, it is important to design near-field charging pads that are still able to uniquely identify different types of devices and, when a wireless power receiver is detected, figure out if that wireless power receiver is authorized to receive wireless power.

<FIG> is a block diagram of the RF power transmitter integrated circuit <NUM> (the "integrated circuit") in accordance with some embodiments. In some embodiments, the integrated circuit <NUM> includes a CPU subsystem <NUM>, an external device control interface, an RF subsection for DC to RF power conversion, and analog and digital control interfaces interconnected via an interconnection component, such as a bus or interconnection fabric block <NUM>. In some embodiments, the CPU subsystem <NUM> includes a microprocessor unit (CPU) <NUM> with related Read-Only-Memory (ROM) <NUM> for device program booting via a digital control interface, e.g. an I<NUM>C port, to an external FLASH containing the CPU executable code to be loaded into the CPU Subsystem Random Access Memory (RAM) <NUM> (e.g., memory <NUM>, <FIG>) or executed directly from FLASH. In some embodiments, the CPU subsystem <NUM> also includes an encryption module or block <NUM> to authenticate and secure communication exchanges with external devices, such as wireless power receivers that attempt to receive wirelessly delivered power from the RF charging pad <NUM>.

In some embodiments, executable instructions running on the CPU (such as those shown in the memory <NUM> in <FIG> and described below) are used to manage operation of the RF charging pad <NUM> and to control external devices through a control interface, e.g., SPI control interface <NUM>, and the other analog and digital interfaces included in the RF power transmitter integrated circuit <NUM>. In some embodiments, the CPU subsystem also manages operation of the RF subsection of the RF power transmitter integrated circuit <NUM>, which includes an RF local oscillator (LO) <NUM> and an RF transmitter (TX) <NUM>. In some embodiments, the RF LO <NUM> is adjusted based on instructions from the CPU subsystem <NUM> and is thereby set to different desired frequencies of operation, while the RF TX converts, amplifies, modulates the RF output as desired to generate a viable RF power level.

In the descriptions that follow, various references are made to antenna zones and power-transfer zones, which terms are used synonymously in this disclosure. In some embodiments the antenna/ power-transfer zones may include antenna elements that transmit propagating radio frequency waves but, in other embodiments, the antenna/ power transfer zones may instead include capacitive charging couplers that convey electrical signals but do not send propagating radio frequency waves.

In some embodiments, the RF power transmitter integrated circuit <NUM> provides the viable RF power level (e.g., via the RF TX <NUM>) to an optional beamforming integrated circuit (IC) <NUM>, which then provides phase-shifted signals to one or more power amplifiers <NUM>. In some embodiments, the beamforming IC <NUM> is used to ensure that power transmission signals sent using two or more antennas <NUM> (e.g., each antenna <NUM> may be associated with a different antenna zone <NUM> or may each belong to a single antenna zone <NUM>) to a particular wireless power receiver are transmitted with appropriate characteristics (e.g., phases) to ensure that power transmitted to the particular wireless power receiver is maximized (e.g., the power transmission signals arrive in phase at the particular wireless power receiver). In some embodiments, the beamforming IC <NUM> forms part of the RF power transmitter IC <NUM>. In embodiments in which capacitive couplers (e.g., capacitive charging couplers <NUM>) are used as the antennas <NUM>, then optional beamforming IC <NUM> may not be included in the RF power transmitter integrated circuit <NUM>.

In some embodiments, the RF power transmitter integrated circuit <NUM> provides the viable RF power level (e.g., via the RF TX <NUM>) directly to the one or more power amplifiers <NUM> and does not use the beamforming IC <NUM> (or bypasses the beamforming IC if phase-shifting is not required, such as when only a single antenna <NUM> is used to transmit power transmission signals to a wireless power receiver).

In some embodiments, the one or more power amplifiers <NUM> then provide RF signals to the antenna zones <NUM> (also referred to herein as "power-transfer zones") for transmission to wireless power receivers that are authorized to receive wirelessly delivered power from the RF charging pad <NUM>. In some embodiments, each antenna zone <NUM> is coupled with a respective PA <NUM> (e.g., antenna zone <NUM>-<NUM> is coupled with PA <NUM>-<NUM> and antenna zone <NUM>-N is coupled with PA <NUM>-N). In some embodiments, multiple antenna zones are each coupled with a same set of PAs <NUM> (e.g., all PAs <NUM> are coupled with each antenna zone <NUM>). Various arrangements and couplings of PAs <NUM> to antenna zones <NUM> allow the RF charging pad <NUM> to sequentially or selectively activate different antenna zones in order to determine the most efficient antenna zone <NUM> to use for transmitting wireless power to a wireless power receiver (as explained in more detail below in reference to <FIG>, <NUM>, and 11A-11E). In some embodiments, the one or more power amplifiers <NUM> are also in communication with the CPU subsystem <NUM> to allow the CPU <NUM> to measure output power provided by the PAs <NUM> to the antenna zones of the RF charging pad <NUM>.

<FIG> also shows that, in some embodiments, the antenna zones <NUM> of the RF charging pad <NUM> may include one or more antennas 210A-N. In some embodiments, each antenna zones of the plurality of antenna zones includes one or more antennas <NUM> (e.g., antenna zone <NUM>-<NUM> includes one antenna <NUM>-A and antenna zones <NUM>-N includes multiple antennas <NUM>). In some embodiments, a number of antennas included in each of the antenna zones is dynamically defined based on various parameters, such as a location of a wireless power receiver on the RF charging pad <NUM>. In some embodiments, the antenna zones may include one or more of the meandering line antennas described in more detail below. In some embodiments, each antenna zone <NUM> may include antennas of different types (e.g., a meandering line antenna and a loop antenna), while in other embodiments each antenna zone <NUM> may include a single antenna of a same type (e.g., all antenna zones <NUM> include one meandering line antenna), while in still other embodiments, the antennas zones may include some antenna zones that include a single antenna of a same type and some antenna zones that include antennas of different types. In some embodiments the antenna/ power-transfer zones may also or alternatively include capacitive charging couplers that convey electrical signals but do not send propagating radio frequency waves. Antenna zones are also described in further detail below.

In some embodiments, the RF charging pad <NUM> may also include a temperature monitoring circuit that is in communication with the CPU subsystem <NUM> to ensure that the RF charging pad <NUM> remains within an acceptable temperature range. For example, if a determination is made that the RF charging pad <NUM> has reached a threshold temperature, then operation of the RF charging pad <NUM> may be temporarily suspended until the RF charging pad <NUM> falls below the threshold temperature.

By including the components shown for RF power transmitter circuit <NUM> (<FIG>) on a single chip, such transmitter chips are able to manage operations at the transmitter chips more efficiently and quickly (and with lower latency), thereby helping to improve user satisfaction with the charging pads that are managed by these transmitter chips. For example, the RF power transmitter circuit <NUM> is cheaper to construct, has a smaller physical footprint, and is simpler to install. Furthermore, and as explained in more detail below in reference to <FIG>, the RF power transmitter circuit <NUM> may also include a secure element module <NUM> (e.g., included in the encryption block <NUM> shown in <FIG>) that is used in conjunction with a secure element module <NUM> (<FIG>) or a receiver <NUM> to ensure that only authorized receivers are able to receive wirelessly delivered power from the RF charging pad <NUM> (<FIG>).

<FIG> is a block diagram of a charging pad <NUM> in accordance with some embodiments. The charging pad <NUM> is an example of the charging pad <NUM> (<FIG>), however, one or more components included in the charging pad <NUM> are not included in the charging pad <NUM> for ease of discussion and illustration.

The charging pad <NUM> includes an RF power transmitter integrated circuit <NUM>, one or more power amplifiers <NUM>, and a transmitter antenna array <NUM> having multiple antenna zones. Each of these components is described in detail above with reference to <FIG> and <FIG>. Additionally, the charging pad <NUM> includes a switch <NUM> (i.e., transmitter-side switch), positioned between the power amplifiers <NUM> and the antenna array <NUM>, having a plurality of switches <NUM>-A, <NUM>-B,. The switch <NUM> is configured to switchably connect one or more power amplifiers <NUM> with one or more antenna zones of the antenna array <NUM> in response to control signals provided by the RF power transmitter integrated circuit <NUM>.

To accomplish the above, each switch <NUM> is coupled with (e.g., provides a signal pathway to) a different antenna zone of the antenna array <NUM>. For example, switch <NUM>-A may be coupled with a first antenna zone <NUM>-<NUM> (<FIG>) of the antenna array <NUM>, switch <NUM>-B may be coupled with a second antenna zone <NUM>-<NUM> of the antenna array <NUM>, and so on. Each of the plurality of switches <NUM>-A, <NUM>-B,. <NUM>-N, once closed, creates a unique pathway between a respective power amplifier <NUM> (or multiple power amplifiers <NUM>) and a respective antenna zone of the antenna array <NUM>. Each unique pathway through the switch <NUM> is used to selectively provide RF signals to specific antenna zones of the antenna array <NUM>. It is noted that two or more of the plurality of switches <NUM>-A, <NUM>-B,. <NUM>-N may be closed at the same time, thereby creating multiple unique pathways to the antenna array <NUM> that may be used simultaneously.

In some embodiments, the RF power transmitter integrated circuit <NUM> is coupled to the switch <NUM> and is configured to control operation of the plurality of switches <NUM>-A, <NUM>-B,. <NUM>-N (illustrated as a "control out" signal in <FIG> and <FIG>). For example, the RF power transmitter integrated circuit <NUM> may close a first switch <NUM>-A while keeping the other switches open. In another example, the RF power transmitter integrated circuit <NUM> may close a first switch <NUM>-A and a second switch <NUM>-B, and keep the other switches open (various other combinations and configuration are possible). Moreover, the RF power transmitter integrated circuit <NUM> is coupled to the one or more power amplifiers <NUM> and is configured to generate a suitable RF signal (e.g., the "RF Out" signal) and provide the RF signal to the one or more power amplifiers <NUM>. The one or more power amplifiers <NUM>, in turn, are configured to provide the RF signal to one or more antenna zones of the antenna array <NUM> via the switch <NUM>, depending on which switches <NUM> in the switch <NUM> are closed by the RF power transmitter integrated circuit <NUM>.

To further illustrate, as described in some embodiments below, the charging pad is configured to transmit regular power transmission signals in addition to the test power transmission signals, using different antenna zones, e.g., depending on a location of a receiver on the charging pad. Accordingly, when a particular antenna zone is selected for transmitting test signals or regular power signals, a control signal is sent to the switch <NUM> from the RF power transmitter integrated circuit <NUM> to cause at least one switch <NUM> to close. In doing so, an RF signal from at least one power amplifier <NUM> can be provided to the particular antenna zone using a unique pathway created by the now-closed at least one switch <NUM>.

In some embodiments, the switch <NUM> may be part of (e.g., internal to) the antenna array <NUM>. Alternatively, in some embodiments, the switch <NUM> is separate from the antenna array <NUM> (e.g., the switch <NUM> may be a distinct component, or may be part of another component, such as the power amplifier(s) <NUM>). It is noted that any switch design capable of accomplishing the above may be used, and the design of the switch <NUM> illustrated in <FIG> is merely one example.

<FIG> is a block diagram illustrating certain components of an RF charging pad <NUM> in accordance with some embodiments. In some embodiments, the RF charging pad <NUM> includes an RF power transmitter IC <NUM> (and the components included therein, such as those described above in reference to <FIG>), memory <NUM> (which may be included as part of the RF power transmitter IC <NUM>, such as nonvolatile memory <NUM> that is part of the CPU subsystem <NUM>), and one or more communication buses <NUM> for interconnecting these components (sometimes called a chipset). In some embodiments, the RF charging pad <NUM> includes one or more sensor(s) <NUM> (discussed below). In some embodiments, the RF charging pad <NUM> includes one or more output devices such as one or more indicator lights, a sound card, a speaker, a small display for displaying textual information and error codes, etc. In some embodiments, the RF charging pad <NUM> includes a location detection device, such as a GPS (global positioning satellite) or other geo-location receiver, for determining the location of the RF charging pad <NUM>.

In some embodiments, the one or more sensor(s) <NUM> include one or more thermal radiation sensors, ambient temperature sensors, humidity sensors, IR sensors, occupancy sensors (e.g., RFID sensors), ambient light sensors, motion detectors, accelerometers, and/or gyroscopes.

In some embodiments, the RF charging pad <NUM> further includes a signature-signal receiving circuit <NUM> (<FIG> and <FIG>), a reflected power coupler <NUM> (e.g., <FIG> and <FIG>), and a capacitive charging coupler <NUM> (<FIG>).

The memory <NUM> includes high-speed random access memory, such as DRAM, SRAM, DDR SRAM, or other random access solid state memory devices; and, optionally, includes non-volatile memory, such as one or more magnetic disk storage devices, one or more optical disk storage devices, one or more flash memory devices, or one or more other non-volatile solid state storage devices. The memory <NUM>, or alternatively the non-volatile memory within memory <NUM>, includes a non-transitory computer-readable storage medium. In some embodiments, the memory <NUM>, or the non-transitory computer-readable storage medium of the memory <NUM>, stores the following programs, modules, and data structures, or a subset or superset thereof:.

Each of the above-identified elements (e.g., modules stored in memory <NUM> of the RF charging pad <NUM>) is optionally stored in one or more of the previously mentioned memory devices, and corresponds to a set of instructions for performing the function(s) described above. The above identified modules or programs (e.g., sets of instructions) need not be implemented as separate software programs, procedures, or modules, and thus various subsets of these modules are optionally combined or otherwise rearranged in various embodiments. In some embodiments, the memory <NUM>, optionally, stores a subset of the modules and data structures identified above.

<FIG> is a block diagram illustrating a representative receiver device <NUM> (also sometimes called a receiver, power receiver, or wireless power receiver) in accordance with some embodiments. In some embodiments, the receiver device <NUM> includes one or more processing units (e.g., CPUs, ASICs, FPGAs, microprocessors, and the like) <NUM>, one or more communication components <NUM>, memory <NUM>, antenna(s) <NUM>, power harvesting circuitry <NUM>, and one or more communication buses <NUM> for interconnecting these components (sometimes called a chipset). In some embodiments, the receiver device <NUM> includes one or more sensor(s) <NUM> such as the one or sensors <NUM> described above with reference to <FIG>. In some embodiments, the receiver device <NUM> includes an energy storage device <NUM> for storing energy harvested via the power harvesting circuitry <NUM>. In various embodiments, the energy storage device <NUM> includes one or more batteries, one or more capacitors, one or more inductors, and the like.

In some embodiments, the power harvesting circuitry <NUM> includes one or more rectifying circuits and/or one or more power converters. In some embodiments, the power harvesting circuitry <NUM> includes one or more components (e.g., a power converter) configured to convert energy from power waves and/or energy pockets to electrical energy (e.g., electricity). In some embodiments, the power harvesting circuitry <NUM> is further configured to supply power to a coupled electronic device, such as a laptop or phone. In some embodiments, supplying power to a coupled electronic device include translating electrical energy from an AC form to a DC form (e.g., usable by the electronic device).

In some embodiments, the signature-signal generating circuit <NUM> includes one or more components as discussed with reference to <FIG>.

In some embodiments, the antenna(s) <NUM> include one or more of the meandering line antennas that are described in further detail below. In some embodiments, the antenna(s) <NUM> may also or alternatively include capacitive charging couplers that correspond in structure to those that may be present in a near-field charging pad.

In some embodiments, the receiver device <NUM> includes one or more output devices such as one or more indicator lights, a sound card, a speaker, a small display for displaying textual information and error codes, etc. In some embodiments, the receiver device <NUM> includes a location detection device, such as a GPS (global positioning satellite) or other geo-location receiver, for determining the location of the receiver device <NUM>.

In various embodiments, the one or more sensor(s) <NUM> include one or more thermal radiation sensors, ambient temperature sensors, humidity sensors, IR sensors, occupancy sensors (e.g., RFID sensors), ambient light sensors, motion detectors, accelerometers, and/or gyroscopes.

The communication component(s) <NUM> enable communication between the receiver <NUM> and one or more communication networks. In some embodiments, the communication component(s) <NUM> are capable of data communications using any of a variety of custom or standard wireless protocols (e.g., IEEE <NUM>. <NUM>, Wi-Fi, ZigBee, 6LoWPAN, Thread, Z-Wave, Bluetooth Smart, ISA100.11a, WirelessHART, MiWi, etc.) custom or standard wired protocols (e.g., Ethernet, HomePlug, etc.), and/or any other suitable communication protocol, including communication protocols not yet developed as of the filing date of this document.

The communication component(s) <NUM> include, for example, hardware capable of data communications using any of a variety of custom or standard wireless protocols (e.g., IEEE <NUM>. <NUM>, Wi-Fi, ZigBee, 6LoWPAN, Thread, Z-Wave, Bluetooth Smart, ISA100.11a, WirelessHART, MiWi, etc.) and/or any of a variety of custom or standard wired protocols (e.g., Ethernet, HomePlug, etc.), or any other suitable communication protocol, including communication protocols not yet developed as of the filing date of this document.

Each of the above-identified elements (e.g., modules stored in memory <NUM> of the receiver <NUM>) is optionally stored in one or more of the previously mentioned memory devices, and corresponds to a set of instructions for performing the function(s) described above. The above identified modules or programs (e.g., sets of instructions) need not be implemented as separate software programs, procedures, or modules, and thus various subsets of these modules are optionally combined or otherwise rearranged in various embodiments. In some embodiments, the memory <NUM>, optionally, stores a subset of the modules and data structures identified above. Furthermore, the memory <NUM>, optionally, stores additional modules and data structures not described above, such as an identifying module for identifying a device type of a connected device (e.g., a device type for an electronic device that is coupled with the receiver <NUM>).

In some embodiments, the near-field charging pads disclosed herein may use adaptive loading techniques to optimize power transfer. Such techniques are described in detail in commonly-owned PCT Application No. <CIT> and, in particular, in reference to <FIG>and <NUM>-<NUM>, and the disclosures in this commonly-owned application is hereby expressly incorporated by reference in its entirety.

<FIG> is a block diagram of simplified circuits of an example wireless power-transfer zone <NUM> (e.g., one of the plurality of power-transfer zones 290A-N, <FIG>) located at the RF charging pad <NUM>, and an example wireless power receiver <NUM> (e.g., an instance of the receiver <NUM>, <FIG>), in accordance with some embodiments. In some embodiments, the wireless power receiver <NUM> includes a signature-signal generating circuit <NUM>, as discussed with reference to <FIG>. It is noted that the power-transfer zone <NUM> may be referred to below, or illustrated in the Figures, as a transmitter (TX).

In some embodiments, an oscillator on the receiver device <NUM> includes one or more elements configured to control duty cycle and frequency and modulate a variable load <NUM> at the rectifier DC output port. In some embodiments, the rectifier voltage is encoded as frequency, and the rectifier load current is encoded as duty cycle (or vice versa). In some embodiments, the host <NUM> (e.g., CPU) controls the oscillator frequency and duty cycle, where each frequency/duty pair corresponds to a different message to be delivered to the power-transfer zone <NUM> located at the RF charging pad <NUM>. In some embodiments, the receiver <NUM> includes a power-link monitoring chip with interfaces to the host <NUM> and the rectifier <NUM>, and the power-link monitoring chip can also control the frequency/duty cycle of the oscillator. In some embodiments, the frequency and duty cycle variations are analyzed to recognize whether there are any foreign objects on the RF charging pad <NUM> (e.g., between the RF charging pad <NUM> and the receiver device <NUM> on top of the RF charging pad <NUM>).

In some embodiments, the DC load modulation varies the impedance at the antenna interface <NUM> between the power-transfer zone <NUM> and the receiver <NUM>. In some embodiments, the impedance change causes variations in reflected power (e.g., reflected power <NUM>, <FIG>) at the receiver block <NUM> residing on the power-transfer zone <NUM>, and such receiver block <NUM> decodes the variations to identify the reflected signals including information related to frequency and duty cycle (e.g., frequency and duty cycle are shown in <FIG>). In some embodiments, the rectifier loading conditions are known at the power-transfer zone <NUM>. In some embodiments, it is determined whether the receiver host message is known at the transmit side to identify authorized receivers. In some embodiments, oscillator/modulator are enabled/disabled based on (<NUM>) configurable (voltage) threshold on rectifier DC output and/or (<NUM>) firmware control.

<FIG>and <FIG> show block diagrams illustrating circuits including a rectifier <NUM> coupled to a variable load <NUM> of a receiver device (e.g., receiver device <NUM>, <FIG>), in accordance with some embodiments. In some embodiments, the rectifier <NUM> converts RF power received at the RFin port into DC power at the Vrect port. In some embodiments, the amount of power received is dependent on the amount of power input by the antenna <NUM> (e.g., antenna(s) <NUM>, <FIG>) of the receiver <NUM> and the impedance match between the antenna <NUM> of the receiver <NUM> and the rectifier <NUM>. In some embodiments when the impedances of the antenna <NUM> and the rectifier <NUM> are matched, substantially all of the power from the antenna <NUM> enters the rectifier <NUM> and substantially none of the power is reflected (illustrated by lines <NUM> in <FIG>). When the impedances of the antenna <NUM> and the rectifier <NUM> are not matched, then some power from the antenna <NUM> is reflected off the rectifier <NUM> and the reflected power signals <NUM> are transmitted back to the antenna <NUM> (illustrated by lines <NUM> in <FIG>and <FIG>).

In some embodiments, the reflected power <NUM> is a source of system inefficiency in that it reduces the total amount of DC power that could be obtained from an available amount of RF power. In some embodiments, reflecting all, or a substantial portion, of the RF input power can be useful if no power is intended to be received at the receiver device <NUM>. For example, if the host <NUM> battery is full, then the received power must be dissipated as heat somewhere in the receiver <NUM>. Therefore, in some embodiments, it can be more thermally effective to reflect that power back out of the antenna <NUM>.

In some embodiments, the reflected power signals <NUM> can be modulated for the purposes of data communications, as referred to as "load modulation" and this can be accomplished in some embodiments by placing a variable load <NUM> at the rectifier RFin port (<FIG>). In some embodiments in a load-modulated system, the amount of power reflected is controlled by a variable load <NUM> located at the RF input (<FIG>). This type of control has disadvantages: even when OFF, the variable load <NUM> introduces a loss at the RF frequency and therefore reduces the RF to DC conversion efficiency. In some embodiments, very high Q bandpass filters are needed to filter the modulation spectrum for regulatory compliance.

Controlling the amount of reflected power <NUM> may also be used for conveying data to a signature-signal receiving circuit <NUM> (e.g., included in a respective power-transfer zone of an RF charging pad). In some embodiments, the signature-signal receiving circuit <NUM> is a universal circuit for the NF charging pad <NUM> (i.e., the NF charging pad <NUM> includes a single signature-signal receiving circuit <NUM> that services each of the power-transfer zones <NUM>). Alternatively, in some embodiments, each of the power-transfer zones (e.g., zone <NUM>) includes its own signature-signal receiving circuit <NUM> (as shown in <FIG>).

In accordance with the embodiments disclosed herein, the inventors have determined that it is advantageous to locate the variable load <NUM> at the Vrect port (DC side) of the rectifier <NUM> (<FIG>), as is discussed in more detail below. In some embodiments, the variable load <NUM> can be moved to the DC side of the rectifier <NUM> (<FIG>). The rectifier <NUM> thus operates both as a downconverter (converting RF power to DC power) and an upconverter (converting the load modulation at Vrect to the RF frequency at RFin). In some embodiments, having the variable load <NUM> located at the DC side of the rectifier <NUM> solves disadvantages mentioned above that are present when the variable load <NUM> is placed at the RFin port.

<FIG> is a block diagram illustrating circuits including a reflect switch <NUM> within a wireless power receiver <NUM> (pictured in <FIG>) in accordance with some embodiments. In some embodiments, while the variable load <NUM> is used to reflect small amounts of power back out of the receive antenna <NUM>, a reflect switch <NUM> is used to reflect all, or a substantial portion, of the received power. The reflect switch <NUM> could be located at the RFin port, however this would present the same disadvantages as discussed with reference to <FIG>, which illustrates an example of the variable load <NUM> coupled to the Rfin port. In some embodiments, these disadvantages are largely mitigated by placing the reflect switch <NUM> at the DC port (e.g., the Vrect port) of the rectifier <NUM>. In some embodiments, when the reflect switch <NUM> is OFF, the reflect switch <NUM> does nothing. When the reflect switch <NUM> is ON, it presents a very low impedance (e.g., a short circuit) load at the DC side of the rectifier <NUM>. Similarly, a low impedance load is seen at the RFin port of the rectifier <NUM>, which presents a substantial impedance mismatch between the antenna <NUM> and the rectifier <NUM>. Therefore, when the reflect switch <NUM> is ON, a substantial percentage of the input power from the antenna <NUM> is reflected back out of the antenna <NUM> and does not get converted to DC power by the rectifier <NUM>.

<FIG> is a block diagram illustrating an example of a signature-signal generating circuit <NUM> of the wireless power receiver <NUM> in accordance with some embodiments. In some embodiments, the signature-signal generating circuit <NUM> includes a PFM/PWM (pulse-frequency modulation / pulse-width modulation) generator <NUM> to control the variable load <NUM> for generating a valid receiver "signature" (also referred to herein as a signature signal). In some embodiments, the signature-signal generating circuit <NUM> further includes (or is in communication with) a window comparator <NUM> to disable the control scheme unless sufficient power is available at Vrect to turn on all the circuitry. In some embodiments, the signature-signal generating circuit <NUM> further includes a current sensor <NUM> that converts the rectifier load current into a voltage which is received by the PFM/PWM generator <NUM>. In some embodiments, the PFM/PWM generator <NUM> also senses Vrect directly. In some embodiments, the reflect switch <NUM> is also part of the signature-signal generating circuit <NUM>.

In some embodiments, the window comparator <NUM>, current sensor <NUM>, and PFM/PWM generator <NUM>, and any other auxiliary circuitry can be powered by power signals that are transmitted from the power-transfer zone <NUM>, rectified by the rectifier <NUM>, and supplied from the Vrect port, such that the system is independent of the host battery. Thus, even when the host battery of the receiver device <NUM> is completely dead, the signature-signal generating circuit <NUM> in the receiver device <NUM> can still be powered by the power signals received from the power-transfer zone <NUM> to generate signals with signatures. Such signals with signatures are further reflected back to the power-transfer zone <NUM> for sampling and analyzing whether there is any foreign object placed between the power-transfer zone <NUM> and the receiver <NUM>, and/or whether the receiver <NUM> is authorized to receive power from the power-transfer zone <NUM> (or the charging pad <NUM> in general).

In some embodiments, the PWM/PFM generator <NUM> converts the current sense and voltage sense inputs to a pulse train where the pulse frequency is dependent on the sensed current and the pulse width is dependent on the sensed voltage (or vice versa). In some embodiments, the pulse train is applied to the variable load <NUM>, which therefore represents a pulsed load at the port Vrect, and this pulsed load is upconverted to RF by the rectifier <NUM> as previously explained. Ultimately, the pulsed load will be sensed by the power-transfer zone <NUM> for sampling and analyzing.

<FIG> illustrates a block diagram that shows an example power-transfer zone <NUM> including a signature-signal receiving circuit <NUM> in accordance with some embodiments. In some embodiments, the coupling network impedance is sensed by the reflected power coupler <NUM>. In some embodiments, the reflected power coupler <NUM> is used to measure the impedance being reflected back from the receiver <NUM> to the antenna <NUM> (e.g., antenna <NUM>, <FIG>) of the power-transfer zone <NUM>. In some embodiments, due to a mismatch between the power-transfer zone <NUM> and the receiver <NUM> caused by an interference from a foreign object or a signal exchange with an authorized receiver, some power signals are being reflected by the receiver <NUM>. A portion of such reflected power signals <NUM> is received at the power-transfer zone <NUM>'s antenna <NUM>, and the impedance is measured by the reflected power coupler <NUM> at the power-transfer zone <NUM>. After comparing the received reflected power <NUM> and the original transmitted power, the power-transfer zone <NUM> can determine an extent of a mismatch between the power-transfer zone <NUM> and the receiver <NUM>. For example, if <NUM>/<NUM> of the reflected power <NUM> received at the power-transfer zone <NUM> can be sensed by the reflected power coupler <NUM>, and when <NUM>/<NUM> of the original transmitted power is received at the reflected power coupler <NUM>, it can be determined that the receiver <NUM> does not take any power signals from the power-transfer zone <NUM>.

In some embodiments, the reflected power signals <NUM> received from the receiver <NUM> are processed and analyzed by the signature-signal receiving circuit <NUM>. For example, the received reflected signal <NUM> is amplified, filtered, and demodulated using an amplitude modulator (AM) detector <NUM>. In some embodiments, an automatic gain control (AGC) is implemented. In some embodiments, after demodulation, the digitally-sampled signals are matched with antenna fingerprint, e.g., by data analysis block <NUM>. In some embodiments, the rectifier loading conditions are sensed. In some embodiments, Message ID is decoded from the received reflected signals as further shown in <FIG> (and discussed further below).

<FIG>show respective block diagrams illustrating various example circuits of power-transfer zones <NUM> and wireless receivers <NUM> in accordance with some embodiments. In some embodiments, the pulsed load at RFin modulates the amount of reflected power <NUM> which propagates out of an antenna <NUM> of the wireless power receiver <NUM>. In some embodiments, some of this reflected power enters the transmitting antenna <NUM> (also referred to as a "power-transferring element"), and some of that in turn is coupled into the receive port of the load-modulation receiver on the power-transmitter unit. As discussed below, the reflected power is received using an AM receiver topology with variable gain stages and AGC for optimal SNR adjustment. In some embodiments, if a foreign object <NUM> is placed on the receiver <NUM>, there is also reflected power from the surface of the foreign object <NUM>, which is also sensed by the AM receiver <NUM>.

In some embodiments, the received data stream is analyzed to extract the receiver signature waveform (its "signature signal"). In some embodiments, if the object is a valid receiver <NUM>, then the signature signal is the PWM/PFM pulse train previously described. Upon correctly decoding the pulse train (or lack thereof), the power-transfer zone <NUM> can determine the system state from among the following options: <NUM>) no object on top, <NUM>) one or more foreign objects on top, <NUM>) valid receiver only, and <NUM>) foreign object in between receiver and a surface of the RF charging pad.

In some embodiments, upon detection of a wireless power receiver <NUM>, the power-transfer zone <NUM> may apply several power levels and measure changes in the PWM/PFM pulse train to authenticate an authorized receiver.

In some embodiments, other messages may be passed from the receiver <NUM> to the power-transfer zone <NUM> using the "control" pin(s) which can modify load modulation. In some embodiments, the messages received by the power-transfer zone <NUM> can be sampled and analyzed to obtain informing regarding receiver conditions, such as battery status (e.g., full/dead/other), temperature, rectifier voltage/current, and future intended actions such as intention to turn on the reflect switch <NUM>.

In some embodiments, the transmission of power signals coexists with other wireless protocols. For example, if the host <NUM> intends to send or receive wireless (Bluetooth, WiFi, LTE, etc.) traffic but cannot because the power-transfer zone <NUM> is on and is interfering with the Bluetooth system, the host <NUM> may wish to stop the power-transmission for an interval to clear the wireless traffic, and then continue the power-transmission. Techniques for managing coexistence of power and data signals are described in commonly-owned <CIT>, which is hereby incorporated by reference in its entirety.

In some embodiments, the host <NUM> (shown in <FIG>) can obtain control of the load modulation using the "control" input. In some embodiments, the host <NUM> can force certain PWM/PFM combinations which are then interpreted as pre-defined messages by the power-transfer zone <NUM>. Examples of such pre-defined messages are discussed with reference to <FIG> below.

In some embodiments, the host <NUM> controls the reflect switch <NUM>. When the reflect switch <NUM> is turned on, Vrect is drawn below the window comparator threshold and the PWM/PFM <NUM> stops. In this case, the power-transfer zone <NUM> detects the absence of a valid receiver signature. The actions under this scenario are programmable per application. In some embodiments, a switch <NUM> (i.e., receiver-side switch) to the host power input is controlled via the host <NUM> and also via the window comparator <NUM> such that the host <NUM> cannot overload the rectifier <NUM> during system startup.

<FIG> lists example messages encoded using signature signals in PFM/PWM pairs, in accordance with some embodiments. In some embodiments, the Frequency/duty pairs (also PFM/PWM pairs) can be selected on the receiver side and interpreted on the transmitter side as passing specific messages. <FIG> lists an example plot of <NUM> frequency / duty pairs, and each pair has a different meaning used to control the power transfer link, implementing coexistence and foreign object detection (FOD). In some embodiments, the PFM/PAM pairs shown in A0-A6 are decoded as a request from the receiver <NUM> to the power-transfer zone <NUM> to reduce power by various amounts. In some embodiments, the PFM/PAM pairs shown in B0-B6 are decoded as a request from the receiver <NUM> to the power-transfer zone <NUM> to increase power by various amounts. In some embodiments, the PFM/PAM pairs shown in C0-C6 are decoded as a request from the receiver <NUM> to the power-transfer zone <NUM> to stop transmitting for various lengths of time then restart, or stop forever.

<FIG> illustrates a simplified diagram showing a highly-coupled near-field capacitive coupler <NUM> (e.g., <FIG>) that is used in a power-transfer zone <NUM> in accordance with some embodiments (e.g., the coupler <NUM> can be the antenna <NUM> discussed above with reference to <FIG>). In some embodiments, the highly-coupled near-filed capacitive coupler <NUM> is coupled to the power amplifier <NUM> and the signature-signal receiving circuit <NUM> (<FIG>). In some embodiments, the highly-coupled near-field capacitive coupler <NUM> operates in one of the ISM frequency bands. In some embodiments, no electromagnetic (EM) propagation occurs in the current system. Rather, the wireless power is transmitted and received via capacitive coupling elements between the power-transfer zone <NUM> and the receiver <NUM>. In some embodiments, the capacitive coupling occurs when two coupling elements (one on transmitter side and one on receiver side) are placed in front of each other in an optimum position when desired stackup is placed between two coupling elements.

In some embodiments, there is no limit on the shape, size, and number of the center coupler <NUM> and parasitic elements <NUM>. In some embodiments, the parasitic elements <NUM> can be in the same level as the center coupling element <NUM> or at a higher or a lower level from the center coupling element <NUM>. In some embodiments, the parasitic elements <NUM> are placed around the center coupling element <NUM> to extend X-Y coverage within the planar area of the capacitive coupler <NUM>. In some embodiments, the system is formed as a two-conductor capacitor. In some embodiments, when the coupling elements of the receiver <NUM> and the power-transfer zone <NUM> are misaligned, the parasitic elements <NUM> are effective in forming a multi-conductor capacitive system to maximize the power transfer from the power-transfer zone <NUM> to the receiver <NUM>. In some embodiments, to measure the reflected RF power to the power amplifier <NUM>, there is a coupler circuitry <NUM> (in a form of a chip or printed lines, as shown in <FIG>) to sample the reflected RF power signals <NUM>. In some embodiments, the capacitive charging coupler <NUM> includes a reflecting plane.

In some embodiments, when the receiver antenna <NUM> is placed on top of the transmitting antenna <NUM> (e.g., one of the capacity charging couplers <NUM>), the system shows coupling efficiency of more than a predetermined threshold value (e.g., a minimum acceptable value, such as <NUM>%). In some embodiments, when the transmitting antenna <NUM> and receiver antenna <NUM> are completely standalone, the system is mismatched. As soon as these antennas are placed on top of each-other, both antennas get matched. In some embodiments, the coupling system only works when the designed receiver is placed on top of the transmitting antenna <NUM>. In case of a foreign object <NUM> being placed on top of the power-transfer zone <NUM>, the transmitting antenna <NUM> is not matched. Such mismatch induced by a foreign object <NUM> can be used to detect a foreign object <NUM> placed between the power-transfer zone <NUM> and the receiver <NUM>.

In some embodiments, the coupling between the receiver <NUM> and the power-transfer zone <NUM> reaches a peak when the receiver antenna <NUM> and the transmitting antenna <NUM> are fully aligned/centered (e.g. <NUM>%). In some embodiments, as the receiver antenna <NUM> moves over the transmitting antenna <NUM>, the coupling performance drops, but it remains within an acceptable range (e.g. stays within <NUM>-<NUM>%). In some embodiments, when receiver antenna <NUM> moves outside the minimum coupling range (e.g. <NUM>%), the second/adjacent transmitting antenna <NUM> gets activated for a smooth transition.

In some embodiments, both transmitter and receiver antennas are mismatched, and when the correct placement occurs, both transmitting antenna <NUM> and receiver antenna <NUM> get matched and the maximum power can be obtained from transmitting antenna <NUM> to receiver antenna <NUM>. In some embodiments, highly-coupled near field antenna pairs only work in presence of each other. Therefore, in presence of other types of receiver antennas and/or any other foreign objects, the transmitting antenna <NUM> stays mismatched.

<FIG>shows a plurality of efficiency maps corresponding to various embodiments when the receiver <NUM> is placed over different regions of a power-transfer zone <NUM> that includes one or the couplers <NUM> in accordance with some embodiments. In some embodiments, highly-coupled antenna pairs can be treated as state-machines. In some embodiments as shown in <FIG>, the power-transfer zone <NUM> includes multiple areas with respective charging efficiencies when a receiver <NUM> is displaced on top of the corresponding areas. When the receiver <NUM> is placed on top of the white zone (efficiency ><NUM>%) of the power-transfer zone <NUM> (A - top-left map), the matching of both the receiver <NUM> and power-transfer zone <NUM> is better than -<NUM> dB. When the receiver <NUM> is placed on top of the stippled zone (<NUM>%<efficiency<<NUM>%) of the power-transfer zone <NUM> (B - bottom- left map), the matching of both the receiver <NUM> and power-transfer zone <NUM> is in a range of -<NUM> dB to -<NUM> dB. When the receiver <NUM> is placed on top of the cross-hatched zone (<NUM>%<efficiency<<NUM>%) of the power-transfer zone <NUM> (C - top-right map), the matching of both the receiver <NUM> and power-transfer zone <NUM> is in a range of -<NUM> dB and -<NUM> dB. When the receiver <NUM> is placed on top of the darker zone (efficiency<<NUM>%) of the power-transfer zone <NUM> (D - bottom-right map), the matching of both the receiver <NUM> and power-transfer zone <NUM> is worse than -<NUM> dB.

<FIG> is a flow diagram <NUM> showing a process of detecting a receiver <NUM> by sending beacon signals (also referred to herein as "test power transmission signals") periodically in accordance with some embodiments. In some embodiments, each power-transfer zone starts (<NUM>) a timer so as to send beacon signals periodically. In some embodiments, when the timer expires (<NUM>), each power-transfer zone of the NF charging pad (also referred to herein as an RF charging pad) <NUM> sends a beacon signal (<NUM>). The signature-signal generating circuit <NUM> of the receiver <NUM> (e.g., as discussed in <FIG> and <FIG>) can generate signature-signals based on the beacon signal. Thereafter, each power-transfer zone receives (<NUM>) the receiver <NUM> generated signature-signals and collects analog-to-digital converter <NUM> (ADC) samples. The transmitter beacon signal is disabled (<NUM>), the samples from ADC <NUM> are analyzed (<NUM>), and the zone status is evaluated (<NUM>) (e.g., as discussed with reference to <FIG>). After the zone status is determined and the matching between each respective zone and the receiver <NUM> is evaluated, the timer is restarted (<NUM>) to start the next period for sending beacon signals. In some embodiments, the start step (<NUM>) includes an optional training process as discussed with reference to <FIG> (and in more detail below in reference to <FIG>).

<FIG> is a flow diagram <NUM> showing a process of optional training performed by the power-transfer zone <NUM> in accordance with some embodiments. In some embodiments, optional training is an embodiment for aiding foreign object detection (FOD) using signature-signal-based detection. In some embodiments, this can be done at one time with known sets of receivers and FOD devices. In some embodiments, enough ADC samples are collected (<NUM>) to enable classification of FOD, and the derived parameters provide the ability to classify the object detection status including (<NUM>) no object present (<NUM>), (<NUM>) one or more foreign objects present (<NUM>), (<NUM>) receiver only present (<NUM>), and (<NUM>) foreign object in between receiver <NUM> and power-transfer zone <NUM> (<NUM>). The process further includes analyzing (<NUM>) ADC samples to derive FOD parameters, and storing (<NUM>) the FOD in memory (e.g., in non-volatile memory). More details regarding example training/ learning processes are described below in reference to <FIG>.

<FIG> is a flow diagram <NUM> showing a process of collecting, storing, and analyzing ADC samples performed by the power-transfer zone <NUM> in accordance with some embodiments. In some embodiments, collecting the ADC samples begins at a step <NUM>, and sampling may continue as a preconfigured tight loop in firmware. In some embodiments, firmware runs an optimized loop to collect and store the ADC data in a buffer, which includes enabling (<NUM>) the ADC block, initializing (<NUM>) the buffer, reading (<NUM>) the ADC for data, storing (<NUM>) the collected data (e.g., ADC samples) in the buffer. Next, it is determined whether all the ADC samples are collected (<NUM>). If all the ADC samples are collected (<NUM>-Yes), then the samples are analyzed (<NUM>). However, if all the samples are not collected (<NUM>-No), then the process <NUM> loops back to the reading the ADC (step <NUM>). This can be subjected to timing variation and result in inaccuracies. These variations can be minimized by collecting samples multiple times and averaging to remove the noise.

In some embodiments, operation <NUM> is hardware (HW) assisted. For example, at operation <NUM> harward is used to sample the ADC values at fixed intervals in a pre-defined buffer. Once all the samples are collected, firmware will be notified and subsequent operations shown in <FIG> may continue. This guarantees tight timing for sampling and gives more accurate result. Also the firmware is not blocked in a dead loop of collecting samples.

<FIG> is a flow diagram <NUM> showing a process of analyzing ADC samples performed by a power-transfer zone <NUM> in accordance with some embodiments. In some embodiments, after the ADC samples are collected (<NUM>), a baseline of the collected ADC samples is determined. In one example, the average of the collected ADC samples is determined (<NUM>). Then each ADC sample is compared against the determined baseline, e.g., the average of the collected ADC samples (<NUM>). When an ADC sample is greater than the calculated average (<NUM>-Yes), a high-count is incremented (<NUM>). When an ADC sample is lower than the calculated average (<NUM>-No), a low-count is incremented (<NUM>). Then a duty cycle is calculated (<NUM>) by: high-count/(high-count + low-count), and a frequency is calculated (<NUM>) using time between edges of Fast Fourier transform (FFT). The calculated duty cycle and the frequency are used for evaluating zone status (<NUM>) as discussed with reference to <FIG>.

<FIG> is a flow diagram <NUM> showing a process of evaluating zone status (<NUM>) to determine whether there is a foreign object and/or a receiver present in accordance with some embodiments. In some embodiments, the calculated frequency and duty cycle are compared (<NUM>) against factory-calibrated data. It is then determined whether only a receiver is present (<NUM>). In accordance with a determination that only a receiver is present (<NUM>-Yes), the presence of the receiver is reported (<NUM>) and the charging of the receiver by the antenna zone (e.g., by the power-transfer zone <NUM>) is enabled (<NUM>). In some embodiments, the system waits (<NUM>) for the receiver to connect over Bluetooth. When the receiver is connected over Bluetooth (<NUM>-Yes), the wireless power signals are acquired from the transmitter power control (<NUM>). When the receiver is not connected over Bluetooth (<NUM>-No), the charging of the receiver is disabled (<NUM>).

In some embodiments, when it is determined that a receiver is present, it is also determined whether a foreign object is present with the receiver. In some embodiments, when a receiver <NUM> and a foreign object <NUM> are identified (<NUM>), the charging of the receiver with the foreign object is allowed (<NUM>); and, then the charging process can be enabled. In some embodiments, when only foreign object is detected (<NUM>), the presence of the foreign object is reported (<NUM>). In some embodiments, when no foreign object is detected, it is determined that no object (<NUM>), e.g., neither a receiver nor a foreign object, is present.

<FIG> are flow diagrams showing a method <NUM> of operating a near-field charging pad, in accordance with some embodiments. Operations of the method <NUM> are performed by a near-field charging pad (e.g. RF charging pad <NUM>, <FIG> and <FIG>) or by one or more components thereof (e.g., those described above with reference to <FIG> and <FIG>). In some embodiments, the method <NUM> corresponds to instructions stored in a computer memory or computer-readable storage medium (e.g., memory <NUM> of the RF charging pad <NUM>, <FIG>).

The near-field charging pad includes one or more processors (e.g., CPU <NUM>, <FIG>), a wireless communication component (e.g., communication component(s) <NUM>, <FIG> and <FIG>), and a plurality of power-transfer zones (e.g., antenna zones <NUM>-<NUM> and <NUM>-N, <FIG>; power-transfer zone <NUM>, <FIG>) that each respectively include at least one power-transferring element (e.g., one of antennas <NUM>, <FIG>, which may be one of the antennas <NUM> described in reference to Figures 3A-6E in commonly-owned PCT Application No. <CIT>, which was incorporated by reference above, the antennas <NUM> may also be one or more of the capacitive couplers <NUM> described above in reference to <FIG>) and a signature-signal receiving circuit (e.g., the circuit <NUM> described above in reference to <FIG>, <FIG> and <FIG>, and the signature-signal receiving circuit may also include a reflected power coupler <NUM>) (<NUM>).

In some embodiments, the near-field charging pad includes distinct power-transferring elements that are each included in respective power-transfer zones. For example, as shown in <FIG>, an antenna zone <NUM>-<NUM> includes an antenna <NUM>-A. In another example, as is also shown in <FIG>, an antenna zone <NUM>-N includes multiple antennas. The antenna zones may also be referred to as antenna groups, such that the near-field charging pad includes a plurality of antenna/ power-transfer zones or groups, and each respective zone/group includes at least one of the distinct antenna elements (e.g., at least one antenna <NUM>). It should be noted that an antenna/ power-transfer zone can include any number of antennas, and that the numbers of antennas associated with a particular antenna/ power-transfer zone may be modified or adjusted (e.g., the CPU subsystem <NUM> of RF power transmitter integrated circuit <NUM> responsible for managing operations of the near-field charging pad <NUM> dynamically defines each antenna/ power-transfer zone at various points in time). In some embodiments, each antenna/ power-transfer zone includes a same number of antennas/ power-transferring elements.

In some embodiments, the one or more processors are a component of a single integrated circuit (e.g., RF power transmitter integrated circuit <NUM>, <FIG>) that is used to control operation of the near-field charging pad. In some embodiments, the one or more processors and/or the wireless communication component of the near-field charging pad is/are external to the near-field charging pad, such as one or more processors of a device in which the near-field charging pad is embedded. In some embodiments, the wireless communication component is a radio transceiver (e.g., a BLUETOOTH radio, WI-FI radio, or the like for exchanging communication signals with wireless power receivers).

In some embodiments and with reference to <FIG>, the method <NUM> includes optionally learning (<NUM>) signature signals for different wireless power receivers (e.g., receiver <NUM>, <FIG>) and for other objects (e.g., foreign object <NUM>, <FIG>), and these learned signature signals are stored in a data source (which may be a local memory of the near-field charging pad or which may be hosted externally to the near-field charging pad).

In some embodiments, the one or more processors of the near-field charging pad are in communication with the data source into which each of the learned signature signals is stored. The data source may be hosted internally or externally to the near-field charging pad. In some embodiments, the data source is populated with the one or more predefined signature signals during a configuration process in which each of a plurality of different wireless power receivers is placed on the near-field charging pad to allow the near-field charging pad to detect and then store (in the data source) a respective predefined signature signal for each of the plurality of different wireless power receivers. In some embodiments, after a respective signature signal is learned for a respective wireless power receiver of the different wireless power receivers, a user may provide an indication as to whether the respective wireless power receiver is an authorized wireless power receiver or not. In this way, the near-field charging pad is able to learn signature signals for both authorized and unauthorized wireless power receivers.

In some embodiments, the configuration process also includes placing a plurality of different objects (e.g., keys, coins, various types of liquids, credits cards, coffee mugs, or any other type of household object that a user might place on the near-field charging pad), which are not wireless power receivers, on the near-field charging pad to allow the near-field charging pad to detect and then store (in the data source) a respective predefined signature signal for each of the plurality of different objects.

In some embodiments, during this configuration process, identifiers for each of the different objects are also stored with each of the respective stored signature signals, thereby allowing the near-field charging pad to identify different types of objects based on matching a signature signal to one of the stored signals.

In some embodiments, during the configuration process, signature signals are also learned for combinations of the different wireless power receivers and the plurality of different objects (e.g., each of the different objects may be placed underneath or on top of each of the different wireless power receivers), and these signature signals are also stored in the data source.

Certain implementations of the near-field charging pad may be implemented so that detection of one of the different objects causing the near-field charging pad to cease any transmission of power. In this way, potential damage to any of the different objects may be avoided.

The method <NUM> also includes sending (<NUM>), by a respective power-transferring element included in a first power-transfer zone of the plurality of power-transfer zones, a plurality of test power transmission signals (also termed beacon power transmission signals) with first values for a first set of transmission characteristics. In some embodiments, the first values for the first set of transmission characteristics include a power level for each of the plurality of test power transmission signals that is less than a certain power threshold (e.g., <NUM> dB).

In some embodiments, the sending operation <NUM> is performed based on a predefined time interval, such that at every predefined time interval the test power transmission signals are sent by the first power-transfer zone. In some embodiments, the predefined time interval is <NUM> second, <NUM> seconds, or <NUM> seconds, or some value therebetween. In some embodiments, the near-field charging pad includes a data-communication radio (e.g., a wireless communication component <NUM>, such as a BLUETOOTH radio), and the sending of the plurality of test power transmission signals is performed without receiving any signal via the data-communication radio.

In other words, by allowing the method <NUM> to begin without requiring receipt of any signal via the data-communication radio, the method <NUM> is used to detect that an authorized receiver is present on the near-field charging pad even when that receiver has no charge in its power sources (e.g., its battery is completely drained). Additionally, the method <NUM> is also used to detect authorized receivers on the pad which do not have any data-communication radios at all.

In conjunction with sending each of the plurality of test power transmission signals, the method also includes detecting (<NUM>), using the signature-signal receiving circuit, respective amounts of reflected power (e.g., reflected signals <NUM>, <FIG>) at the first power-transfer zone. The respective amounts of reflected power may include amounts of power from each of the test power transmission signals that are reflected back to the first power-transfer zone. As is discussed in more detail below, these respective amounts of reflected power may be used to allow the near-field charging pad to determine whether an authorized wireless power receiver is located on the near-field charging pad.

Based at least in part on the respective amounts of reflected power, the method <NUM> then includes determining whether (i) an authorized wireless power receiver and/or (ii) an object other than a wireless power receiver is present on a surface of the near-field charging pad that is adjacent to the first power-transfer zone (e.g., a surface of the pad that is immediately above the first antenna zone). In some embodiments, this determination is based at least in part on the respective amounts of reflected power, because the near-field charging pad generates (<NUM>) a signature signal based on the respective amounts of reflected power (e.g., an example way to generate the signature signals based on the reflected amount of power is shown in <FIG>, <FIG>, <FIG>, and <FIG>) and then compares (<NUM>) the generated signature signal to the learned signature signals stored in the data source.

In some embodiments, the signature signal is conveyed to the signature-signal receiving circuit of the first power-transfer zone by encoding the one or more signature signals using manipulations to an impedance value(s) at the wireless power receiver, the manipulations to the impedance value(s) causing the amounts of reflected power to vary at different points in time.

In some embodiments, the manipulations to the impedance value cause the signature-signal receiving circuit to detect variations in the measurements of reflected power and these variations may be decoded to produce the one or more signature signals. In some embodiments, the one or more signature signals comprise a combination of frequency and duty cycle values. An example as to how this may work is described with reference to <FIG>, <FIG>, and <FIG>. In some embodiments, in addition to conveying information regarding whether a wireless power receiver is authorized to receive power from the pad, the one or more signature signals may also be used to convey additional data or messages to the pad. Examples as to how data may be encoded using the signature signals are shown in <FIG>, <FIG>, and <FIG>.

Turning now to <FIG>, the method <NUM> includes determining (<NUM>) whether the signature signal indicates that an authorized receiver and/or any other object (that is not a wireless power receiver) is present on a surface of the first power-transfer zone.

In accordance with a determination that the signature signal indicates that both a receiver and some other object (which is not a wireless power receiver) are present on the surface of the first power-transfer zone, the method <NUM> then includes determining (<NUM>) whether the near-field charging pad is configured to send wireless power while objects (which are not wireless power receivers) are present on the pad.

If it is determined that the pad is configured to send wireless power while objects (which are not wireless power receivers) are present on the pad (<NUM>-Yes), then the method <NUM> includes sending (<NUM>), via the power-transferring element, additional power transmission signals with second values for the first set of transmission characteristics to the authorized wireless power receiver.

If it is determined that the pad is not configured to send wireless power while objects (which are not wireless power receivers) are present on the pad (<NUM>-No), then the method <NUM> includes waiting for a timer to expire (<NUM>), e.g., waiting for a period of a second or two seconds to pass) and then returning to operation <NUM> of <FIG>.

An additional example of detecting a wireless power receiver and some other object on the surface of the first power-transfer zone is provided below. In this example, the determination (<NUM>-Receiver + Object) that both a wireless power receiver and some other object are present on the surface of the first power-transfer zone is based on the comparison (<NUM>) of the signature signal with the one or more predefined signature signals stored in the data source. In this example, the method <NUM> then determines that the near-field charging pad is configured to send power transmission signals while an object other than a wireless power receiver is present on the near-field charging pad; and, after determining that the near-field charging pad is configured to send power transmission signals while an object other than a wireless power receiver is present on the near-field charging pad, the power-transferring element of the first power-transfer zone is then used to send the additional power transmission signals.

In some embodiments, different, third values for the first set of transmission characteristics are used to send the additional power transmission signals when it is determined that an object other than a wireless power receiver is present on the pad. For example, a power level of the additional power transmission signals may be lowered (relative to a power level that is used for the second values for the first set of transmission characteristics) to avoid any potential damage to the object other than the wireless power receiver (e.g., to avoid damaging or destroying a magnetic strip present on a credit card).

Referring back to <FIG>, when it is determined at operation <NUM> that only an authorized receiver is present on the surface of the first power-transfer zone (<NUM>-Receiver Only), then the method proceeds to send, via the power-transferring element, additional power transmission signals with the second values for the first set of transmission characteristics to the authorized wireless power receiver. One specific example of detecting just a receiver is also provided below. In this example, and as was discussed in reference to operations <NUM> and <NUM>, the detected amounts of reflected power at the first power-transfer zone may be used to then determine, using the signature-signal receiving circuit, the signature signal based at least in part on the respective amounts of reflected power at the first power-transfer zone. An example process for collecting measurements of reflected power and collecting the one or more signature signals is shown in <FIG>.

In this example, the method <NUM> also includes determining, based on a comparison of the signature signal with one or more predefined signature signals, that only an authorized wireless power receiver is present on the surface of the near-field charging pad that is adjacent to the first antenna zone. In some embodiments, the authorized wireless power receiver includes a signature-signal generating circuit (e.g., circuit <NUM>, <FIG>) that uses power harvested from the plurality of test power transmission signals to generate the one or more signature signals (as is described in more detail in reference to <FIG> and <FIG>). In this example, in accordance with the determining that only the authorized wireless power receiver is present on the surface, the method <NUM> further includes transmitting, by the respective power-transferring element included in the first antenna zone, additional power transmission signals with the second values for the first set of transmission characteristics.

In some embodiments, the signature-signal receiving circuit (e.g., circuit <NUM>, <FIG>) at the first power-transfer zone is configured to detect measurements of reflected power at the first antenna zone and these measurements may change based on the presence or absence of objects on a surface adjacent to the first antenna zone (e.g., a surface of the pad that is immediately above the first antenna zone). Additionally, the signature-signal generating circuit may be configured to cause impedance changes at the wireless power receiving, which allows for the generation of different signature signals by the signature-signal generating circuit and, thereby, to cause the receipt of the different signature signals at the signature-signal receiving circuit of the first antenna zone. As discussed above (e.g., in reference to <FIG>, <FIG>, and <FIG>), this allows for creation of a scheme in which authorized wireless power receivers may be detected based on the different signature signals, and unauthorized wireless power receivers may be ignored, to avoid allowing unauthorized devices to leach power from the system.

Also referencing <FIG>, when it is determined that only an object (which is not a wireless power receiver) is present on the surface of the first power-transfer zone, then the method <NUM> includes waiting for a timer to expire (<NUM>) (e.g., waiting for a period of a second or two seconds to pass) and then returning to operation <NUM> of <FIG>.

Referring back to <FIG>, and to allow for detecting either multiple wireless power receivers on the pad and/or to detect objects and receivers located over different power-transfer zones of the pad, the method <NUM> includes repeating (906A) operations <NUM>-<NUM> for each power-transfer zone of the plurality of power-transfer zones.

Accordingly, in conjunction (either at the same time as or during different, non-overlapping time periods) with the sending (<NUM>) of the plurality of test power transmission signals, the method <NUM> includes sending a respective plurality of test power transmission signals by respective power-transferring elements included in each power-transfer zone of the plurality of power-transfer zones; detecting, using respective signature-signal receiving circuits included in each respective power-transfer zone of the plurality of power-transfer zones, respective amounts of reflected power at each of the plurality of power-transfer zones; and determining, for each power-transfer zone of the plurality of power-transfer zones, whether (a) a wireless power receiver or (ii) an object other than a wireless power receiver is present at a respective surface adjacent to each of the plurality of power-transfer zones.

Based on the respective amounts of reflected power detected at a second power-transfer zone of the plurality of power-transfer zones, the method <NUM> may include: determining that an object other than a wireless power receiver is present at the second power-transfer zone; and in accordance with determining that the object other than a wireless power receiver is present at the second power-transfer zone, determining whether the near-field charging pad is configured to transmit wireless power while one or more objects are present on the near-field charging pad. In embodiments in which an object other than a wireless power receiver is detected at a power-transfer zone different from a zone over which an authorized wireless power receiver is detected, the sending of the additional power transmission signals is only performed after determining that the near-field charging pad is configured to send wireless power while one or more objects are present on the near-field charging pad.

In some embodiments, the near-field charging pad is configured with a parameter that indicates whether it is allowed to send power while foreign objects (e.g., objects other than wireless power receivers) are present on the pad. For instance, an owner or operator of the pad may set this parameter during a setup procedure for the pad. In some embodiments, the classifying may also be performed in a more granular fashion, e.g., to determine types of objects that are not wireless power receivers (e.g., metallic objects, non-metallic objects, credit cards, spilled liquids, etc.).

In some embodiments, the power transmission signals discussed above are radio frequency (RF) power transmission signals (e.g., the test power transmission signals and the additional power transmission signals are RF power transmission signals).

All of these examples are non-limiting and any number of combinations and multi-layered structures are possible using the example structures described above.

The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

It will also be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. For example, a first region could be termed a second region, and, similarly, a second region could be termed a first region, without changing the meaning of the description, so long as all occurrences of the "first region" are renamed consistently and all occurrences of the "second region" are renamed consistently. The first region and the second region are both regions, but they are not the same region.

Claim 1:
A method of operating a near-field charging pad, comprising:
at a near-field charging pad (<NUM>) that includes one or more processors (<NUM>) and a plurality of power-transfer zones (<NUM>) that each respectively includes at least one power-transferring element (<NUM>) and a signature-signal receiving circuit:
sending, by a respective power-transferring element included in a first power-transfer zone of the plurality of power-transfer zones, a plurality of test power transmission signals with first values for a first set of transmission characteristics, wherein the test power transmission signals are radio frequency, RF, power transmission signals;
in conjunction with sending each of the plurality of test power transmission signals, detecting, using the signature-signal receiving circuit, respective amounts of reflected power at the first power-transfer zone; and
based at least in part on the respective amounts of reflected power, determining, for each power-transfer zone of the plurality of power-transfer zones, whether (i) an authorized wireless power receiver (<NUM>) and/or (ii) an object other than a wireless power receiver (<NUM>) is present at a respective surface of the near-field charging pad that is adjacent to each of the plurality of power-transfer zones;
wherein:
the one or more processors of the near-field charging pad are in communication with a data source (<NUM>) that includes the one or more predefined signature signals; and
the method further comprises:
in conjunction with the sending of the plurality of test power transmission signals by the respective power-transferring element included in the first power-transfer zone of the plurality of power zones , sending a further respective plurality of test power transmission signals by respective power transferring elements included in each power-transfer zone of the plurality of power-transfer zones; and
detecting, using respective signature-signal receiving circuit included in each respective power-transfer zone of the plurality of power-transfer zones, respective amounts of reflected power at each of the plurality of power-transfer zones.