Systems and methods for sealing and providing wireless power to wearable or implantable devices

Abstract

An example device includes a first housing portion defining a first coupling surface; a second housing portion defining a second coupling surface, the first housing portion being coupled to the second housing portion to form a housing, the first housing portion and the second housing portion defining an opening, the opening intersecting the first coupling surface and the second coupling surface; a first gasket positioned between the first coupling surface and the second coupling surface, the first gasket providing a first seal between the first housing portion and the second housing portion, a printed circuit board (“PCB”) positioned within the housing and coupled to at least one of the first or second housing portions; an electrical connector electrically coupled to the PCB and disposed within the opening; and a second gasket positioned between the electrical connector and the housing, the second gasket providing a second seal between the electrical connector and the housing, wherein the first gasket is positioned adjacent to the second gasket, and wherein compression of the first gasket between the first and second housing portions provides a third seal between the first gasket and the second gasket. Another example device includes a wireless field driver comprising a first antenna coil and a current source electrically coupled to the first antenna coil; an electromagnetic field (“EMF”) sensor comprising a second antenna coil, wherein the EMF sensor is configured to generate a sensor signal indicative of a signal strength from the first antenna coil; a non-transitory computer-readable medium; and a processor in communication with the non-transitory computer-readable medium, the processor being configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to: cause the current source to output current to the first antenna coil to generate a first EMF; estimate a signal strength of the first EMF based on the sensor signal; and adjust the current to the first antenna coil based on the estimated signal strength of the first EMF to maintain power characteristics and generate a second EMF at the first antenna coil.

Description

Technical Field

[0001] The present application relates generally to wearable devices and near-field wireless power transfer, and more particularly to systems and methods for sealing wearable electronic devices and dynamically controlling near-field wireless power. Background Art

[0002] Wearable electronic devices can be used for a variety of reasons. For example, wristwatches, activity monitors, physiological sensors, and the like can be worn to provide information to the wearer or sense characteristics of the wearer. This sensed information can be viewed by the wearer or transmitted to another device, such as the wearer's smartphone. Furthermore, wearable or implantable electronic devices typically draw power from an onboard battery; however, wireless power transfer to such devices is also possible. Wireless power transfer can be used to power electronic devices or charge onboard batteries. This system creates electromagnetic coupling between an antenna in a charger device and an antenna in a target device to transfer power from the charger to the target device. Summary of the Invention

[0003] Various examples are described for sealing and providing wireless power to a wearable or implantable device. One example device includes a first housing portion defining a first coupling surface; a second housing portion defining a second coupling surface, the first housing portion coupled to the second housing portion to form a housing, the first housing portion and the second housing portion defining an opening intersecting the first coupling surface and the second coupling surface; a first gasket positioned between the first coupling surface and the second coupling surface, the first gasket providing a first seal between the first housing portion and the second housing portion; a printed circuit board (“PCB”) positioned within the housing and coupled to at least one of the first or second housing portions; an electrical connector electrically coupled to the PCB and positioned within the opening; and a second gasket positioned between the electrical connector and the housing, the second gasket providing a second seal between the electrical connector and the housing, wherein the first gasket is positioned adjacent to the second gasket, and wherein compression of the first gasket between the first and second housing portions provides a third seal between the first gasket and the second gasket.

[0004] Another example device includes a first housing portion defining a first coupling surface; a second housing portion defining a second coupling surface, the first housing portion being coupled to the second housing portion to form a housing, the first housing portion and the second housing portion defining an opening that intersects the first coupling surface and the second coupling surface; a printed circuit board (“PCB”) disposed within the housing and coupled to at least one of the first or second housing portions; an electrical connector electrically coupled to the printed circuit board and positioned within the opening; a gasket defined to correspond to the first and second coupling surfaces and to the electrical connector; and wherein the gasket is positioned between the first coupling surface and the second coupling surface, the gasket provides a first seal between the first housing portion and the second housing portion, and the electrical connector is positioned to extend through the gasket, the gasket providing a second seal between the electrical connector and the housing.

[0005] An example method includes providing a first housing portion defining a first coupling surface; providing a second housing portion defining a second coupling surface, the first and second housing portions defining a housing when coupled, the housing defining an opening, the opening intersecting the first coupling surface and the second coupling surface; physically coupling a first gasket to one of the first or second coupling surfaces; providing a printed circuit board ("PCB") having an electrical connector; physically coupling the second gasket to the electrical connector; physically coupling the PCB to at least one of the first or second housing portions and engaging the second gasket with at least one of the first or second housing portions; physically coupling one of the first or second housing portions to the other of the first or second housing portions; applying a sealing force to the first and second housing portions to compress the first gasket to establish a first seal; engaging the second gasket with the other of the first or second housing portions to establish a second seal; and engaging the second gasket with the first gasket to establish a third seal.

[0006] Another example method includes providing a first housing portion defining a first coupling surface; providing a second housing portion defining a second coupling surface, the first and second housing portions defining a housing when coupled, the housing defining an opening, the opening intersecting the first coupling surface and the second coupling surface; providing a printed circuit board ("PCB") having an electrical connector; physically coupling the PCB to at least one of the first or second housing portions; engaging a gasket with at least one of the first or second housing portions and the electrical connector; physically coupling one of the first or second housing portions to the other of the first or second housing portions; and applying a sealing force to the first and second housing portions to compress the gasket to establish a first seal; and wherein the electrical connector is positioned to extend through the gasket; the gasket provides a second seal between the electrical connector and the housing.

[0007] Another example device includes a wireless field driver comprising a first antenna coil and a current source electrically coupled to the first antenna coil; an electromagnetic field (“EMF”) sensor comprising a second antenna coil, wherein the EMF sensor is configured to generate a sensor signal indicative of a signal strength from the first antenna coil; a non-transitory computer-readable medium; and a processor in communication with the non-transitory computer-readable medium, the processor being configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to: cause the current source to output current to the first antenna coil to generate a first EMF; estimate a signal strength of the first EMF based on the sensor signal; and adjust the current to the first antenna coil based on the estimated signal strength of the first EMF to maintain power characteristics and generate a second EMF at the first antenna coil.

[0008] An example method includes causing a current source of a wireless field driver of a wireless device to output current to a first antenna coil to generate a first EMF; receiving one or more signals indicating a sensed strength of the first EMF from an EMF sensor of the wireless device, the EMF sensor including a second antenna coil; estimating a strength of the first EMF based on the one or more sensor signals; and adjusting the current based on the estimated strength of the first EMF to generate a second EMF at the first antenna coil.

[0009] An exemplary non-transitory computer-readable medium includes processor-executable instructions to cause the processor to cause a current source of a wireless field driver of a wireless device to output current to a first antenna coil to generate a first EMF; receive one or more signals indicating a sensed intensity of the first EMF from an electromagnetic field (“EMF”) sensor, the EMF sensor including a second antenna coil; determine an intensity of the first EMF based on the one or more signals; and adjust the current based on the sensed intensity of the first EMF to generate a second EMF.

[0010] These illustrative examples are not mentioned to limit or define the scope of the present disclosure, but to provide examples to help understand its scope. Illustrative examples are discussed in the detailed description, which provides further description. The advantages provided by the various examples can be further understood by studying this specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more specific examples and, together with the description of the examples, serve to explain the principles and implementation of the specific examples.

[0012] Figure 1A-1B An example wearable device and charging port are shown;

[0013] Figure 2A-2B shows an exploded view of an example wearable device having a charging port;

[0014] Figure 3-Figure 5 An example device according to the present disclosure is shown;

[0015] Figures 6A-6C showing a cross-sectional view of an example wearable device having a charging port;

[0016] Figure 7A-7B An example wearable device and sealing assembly are shown;

[0017] Figures 8A-8C An example sealing assembly is shown;

[0018] Figure 9-10 An example method for sealing a wearable electronic device is shown;

[0019] Figure 11A An example system for dynamically controlling near-field wireless power is shown;

[0020] Figure 11B A cross-sectional view of an example wireless device for dynamically controlling near-field wireless power is shown;

[0021] Figure 12 An exploded view of an example device for dynamically controlling near-field wireless power is shown;

[0022] Figure 13 An example device for dynamically controlling near-field wireless power is shown;

[0023] Figure 14 Example techniques for dynamically controlling near-field wireless power are shown;

[0024] Figure 15 An example tunable power amplifier suitable for use with an example system for dynamically controlling near-field wireless power is shown;

[0025] Figure 16-17 An example graph showing the duty cycle for a power amplifier to achieve high efficiency at a target impedance;

[0026] Figure 18 a graph showing the supply voltage to achieve a target current at a selected duty cycle;

[0027] Figure 19-20 An example system for dynamically controlling near-field wireless power is shown;

[0028] Figure 21-22 An example method for dynamically controlling near-field wireless power is shown; and

[0029] Figure 23 An example computing device suitable for dynamically controlling near-field wireless power is shown. DETAILED DESCRIPTION

[0030] Examples are described herein in the context of systems and methods for sealingly and wirelessly providing power to wearable or implantable devices. Those skilled in the art will recognize that the following description is illustrative only and is not intended to be limiting in any way. Reference will now be made in detail to implementations of the examples illustrated in the accompanying drawings. Throughout the drawings and the following description, the same reference designators will be used to refer to the same or similar items.

[0031] For the sake of clarity, not all routine features of the examples described herein are shown and described. Of course, it will be appreciated that in developing any such actual implementation, many implementation-specific decisions must be made (such as conforming to application- and business-related constraints) in order to achieve the developer's specific goals, and that these specific goals will vary from implementation to implementation and from developer to developer.

[0032] Some electronic devices can be worn against a user's skin or on their body and can be exposed to many different types of materials that could damage or destroy the sensitive electronics within the wearable device. Because wearable devices can have relatively long lifespans, such as years, they may encounter many different environments. Furthermore, users may occasionally clean the device, which may include rinsing it under the faucet or wearing it in the shower or bath. Therefore, these devices can be sealed during assembly to prevent the ingress of such materials, particularly moisture.

[0033] An illustrative example of such a device has two halves of a mechanical housing that contain and protect the device's electronics. The housing halves are pressed together and sealed during manufacturing to protect the electronics. The seal in this example is a gasket that matches the perimeter of the housing halves and is positioned between the two housing halves when they are secured together, such as with screws or pressure-sensitive adhesive ("PSA"). During this process, the gasket is compressed between the two housing halves and seals the assembled housing.

[0034] However, example wearable devices according to the present disclosure may include one or more ports to allow cables or wires to be connected to the wearable device. In this example, the wearable device has a charging port to allow a charging cable to be connected to the device to charge the device's battery. Therefore, the perimeter of the assembled housing is interrupted by an opening to accommodate the charging port. The opening in this example is perpendicular to the gasket that seals the two housing halves, and therefore, the gasket does not seal the entire perimeter of the housing.

[0035] Instead, the opening is sealed with a second gasket, which is pressed against a connector assembly placed within the opening. The connector assembly includes a connector cover and an electrical connector. The electrical connector provides a connection point for the charging cable and is also electrically connected to a printed circuit board ("PCB") mounted on one of the two housing halves. To compress the second gasket, it is placed between the connector cover and the housing. The PCB is biased toward the outer edge of the housing, which in turn presses the connector cover toward the housing. The PCB is then securely attached to one of the housing halves to maintain the biasing force. The main or "perimeter" gasket discussed above is then pressed between the two housing halves and against the second or "opening" gasket to seal the housing halves and form a seal at the interface of the two gaskets. Thus, the two gaskets together provide a complete seal to prevent moisture and contaminants from entering the wearable device.

[0036] The example device utilizes a connector opening that spans the node between the two housing halves, thereby creating a need to seal the housing halves together and simultaneously seal the connector opening. However, because the planes in which the seals are located are orthogonal to each other, this creates a problem in that the peripheral gasket used to seal the two housing halves together cannot extend through the opening and therefore cannot seal the opening. Furthermore, because two different gaskets are connected, ensuring a tight seal between the two gaskets must be accomplished by applying a compressive force to each gasket. An advantage of using a gasket to seal the two housing parts and the electrical connector, rather than welding or otherwise fusing the two housing parts together to seal the wearable device, is that the device can be reopened to secure or replace components (such as a battery) and then resealed. Furthermore, by using gaskets rather than more complex processes (such as welding, epoxy gluing, or otherwise fusing the two halves together), the manufacturing and assembly processes can be simplified.

[0037] To power or charge an implanted electronic device, a user brings the charger device near the implanted device and activates the charging function, such as by pressing a button or interacting with a touchscreen. The charger device then activates a power amplifier and transmits alternating current (AC) at a predetermined frequency through a transmitting antenna coil to generate an AC electromagnetic field ("EMF"). A corresponding receiving antenna coil in the implanted device couples with the EMF and extracts electromagnetic ("EM") energy from the field, which it then uses to power various electronic components or charge a battery.

[0038] However, the power received by the implanted device may vary based on the strength of the EMF or the quality of the coupling with the EMF (the strength and quality can vary based on the relative position of the antenna coils (e.g., the alignment of the antenna coils or the distance between the coils)). Therefore, the amount of power received by the implanted device may vary. Furthermore, if the target device is unable to send feedback information to the charger device, the charging device still needs to ensure that the appropriate amount of EMF is transmitted. In this example, to help the charger device output EMF with a target power level, the charger device includes an integrated EMF sensor.

[0039] The EMF sensor in this example includes a second antenna coil coaxially aligned with the transmitting antenna coil. This second coil also electromagnetically couples to the EMF and outputs a signal based on the strength of the EMF. The signal from the second antenna coil is sent to both a peak detector and a phase detector. The peak detector receives the signal and outputs a DC value indicating the peak voltage (or current) output by the second antenna coil. The phase detector receives the signal from the second antenna coil and outputs a phase change based on a reference signal.

[0040] Both the peak voltage (or current) signal and the phase change signal are transmitted to a microcontroller, which receives the signal and determines the EMF intensity based on the peak voltage (or current) signal. The phase change signal is used to indicate the RF load impedance or near-field communication received from the target device, for example, the amount of power received by the target device from the EMF. Based on the estimated EMF intensity and the target EMF intensity, the microcontroller executes a proportional-integral-derivative ("PID") feedback control loop to adjust the amount of current output by the power amplifier to achieve the target EMF intensity. Thus, the charger device is able to dynamically adjust the generated EMF intensity in real time or near real time to provide the power required by the target device.

[0041] In addition to estimating EMF intensity and obtaining RF load information, such EMF sensors can perform other functions such as foreign object detection, power amplifier tuning for improved efficiency, and electromagnetic interference ("EMI") mitigation. For example, a receiving antenna coil in a target device typically introduces harmonic oscillations in the generated EMF, while interfering foreign objects typically do not. Therefore, by filtering the signal received from the EMF sensor to identify harmonics, or by identifying the absence of such harmonics, foreign objects can be detected. Alternatively (or additionally), foreign objects can be detected based on a determined RF load impedance exceeding a threshold impedance. Furthermore, EMI mitigation can be employed based on the amplitude of the sensed harmonics. Such harmonics are often associated with EMI, so if the amplitude of one or more sensed harmonics exceeds a threshold, the EMF intensity can be reduced to reduce potential EMI effects.

[0042] Furthermore, the efficiency of the power amplifier can be improved by adjusting its duty cycle based on the detected EMF. To do this, the transmit current is held constant, the duty cycle is varied, and the power usage at each tested duty cycle is determined. The duty cycle can then be selected by determining the lowest power usage calculated across the tested duty cycles.

[0043] Thus, such an exemplary charger is able to adjust its own power output in real time to ensure that the appropriate amount of energy is delivered to the target device. Furthermore, such techniques can enable the use of less complex target devices, such as target devices that lack separate communication capabilities, for example, by omitting Bluetooth ("BT") or BT Low Energy ("BLE") components. Furthermore, according to some examples, other advantages can also be achieved, such as foreign object detection, load impedance detection and power amplifier tuning, as well as EMI mitigation.

[0044] These illustrative examples are given to introduce the reader to the general subject matter discussed herein, and the present disclosure is not limited to these examples. The following sections describe various additional non-limiting examples and examples of systems and methods for sealing and providing wireless power to wearable or implantable devices.

[0045] Now refer to Figure 1A-1B , Figure 1A-1B An example wearable electronic device 100 is shown. Device 100 can be any suitable electronic device and can provide any of a variety of functions to a user. For example, device 100 in this example is used to wirelessly charge or otherwise wirelessly power an implanted device in the wearer's body; however, other types of wearable devices can include sensors such as pulse monitors, accelerometers, electrocardiogram electrodes, etc., or can be user devices such as smart watches, personal communication devices (e.g., emergency communication devices for elderly users), headphones, earbuds, etc.

[0046] Because the device is intended to be worn by a user and used over an extended period of time (e.g., weeks, months, or years), it will be subject to various environmental conditions, such as moisture or running water, that may damage the electronic components within the device. To prevent such damage, the device is sealed to prevent moisture ingress.

[0047] As can be seen, wearable device 100 has a housing that is made by coupling and sealing two housing portions 110, 112 together. In this example, the device is generally disc-shaped, having two housing portions 110, 112, sealed along a circular perimeter. However, it should be understood that any suitable device shape may be used. This perimeter is interrupted by an opening having an electrical connector 120, which can be used to connect an external device, such as a charger or computing device, to charge or communicate with device 100.

[0048] Because the device's housing includes an electrical connector 120 that interrupts the interface between the housing portions 110 and 112, a simple circumferential seal between the two housing portions 110 and 112 will not completely seal the device 100. Furthermore, because wearable devices are intended to be used for weeks, months, or years, they may need to be repaired or parts, such as batteries, replaced, and the device may need to be opened. Therefore, a permanent seal, such as welding or epoxy adhesive gluing, may not be desirable. Instead, as will be discussed in detail below, the device 100 is sealed by one or more gaskets.

[0049] Now refer to Figure 2A-2B , Figure 2A An exploded view of an example wearable device 200 is shown. The device 200 in this example is a wearable wireless charging and power delivery device suitable for use with one or more implantable devices, such as a neurostimulator. The device 200 includes a PCB 213 with associated electronics, such as a processor (e.g., a microcontroller), an RF transceiver, and an electrical connector 220. In this example, the electrical connector is a Universal Serial Bus ("USB") Type-C connector ("USB-C"), but in various examples can be any suitable electrical connector. For example, the electrical connector 220 can be any suitable USB-style connector, a power connector (e.g., connectable to a wall charger), a 3.5 mm headphone jack, etc. Furthermore, while this example device 200 includes only one electrical connector 220, other example devices can include multiple electrical connectors.

[0050] In this example, the PCB 213 is located on top and is physically coupled to the foam pad, such as by a PSA, which is in turn physically coupled to the housing portion 212. The coil antenna is placed around the PCB 213 and is electrically connected to the RF transceiver when assembled.

[0051] and Figure 1A-1B Like the device 100 shown in FIG, the example device 200 includes two housing portions 210, 212 that together form the housing of the device. Figure 1A-1BThe device 100 includes an electrical connector 220 that interrupts the interface between the two housing portions 210, 212 at an opening established by two partial openings 214, 216 (one partial opening defined by each of the two housing portions 210, 212). The opening is partially formed in each of the housing portions 210, 212 by respective partial openings 214, 216 formed in the respective housing portions 210, 212. Then, when the partial openings 214, 216 are aligned and the housing portions 210, 212 are connected together, the opening is formed. It should be understood that the size and shape of the opening (and therefore the partial openings 214, 216) correspond to the type of electrical connector 220 employed in this example. Therefore, in other examples, the opening may have a different size or shape. Furthermore, in examples having multiple electrical connectors, there may be multiple openings formed in the device housing to accommodate each of the electrical connectors, although in some examples, multiple electrical connectors may share a single opening.

[0052] To seal the device 200 from moisture ingress, two gaskets 230 and 232 are employed. Gasket 230 is formed from a foam material shaped to correspond to the perimeter of the two housing portions 210 and 212. The foam material has a PSA coating applied to each side to adhere the gasket to the coupling surfaces 210a and 212a formed in each of the upper and lower housing portions. The gasket material can be provided as a foam tape or cut from a foam pad or other suitable substrate. Furthermore, while foam is used as the gasket material in this example, any suitable gasket material, including compressible plastic, may be used.

[0053] In this example, a coupling surface 210a on one housing portion 210 protrudes from the housing portion 210, while the other coupling surface 212a is recessed in the other housing portion 212. A gasket 230 can then be placed on one of these coupling surfaces 210a, 212a and secured by the PSA until it is pressed against the other coupling surface 210a, 212a when the two housing portions 210, 212 are connected, and a compressive force ("sealing force") is then applied to compress the gasket between the two housing portions 210, 212 to provide a seal.

[0054] from Figure 2AAs can be seen in the figure, gasket 230 has a gap corresponding to the opening formed in the housing for accommodating electrical connector 220. Therefore, a second gasket 232 is employed to seal electrical connector 220 to the housing. In this example, electrical connector 220 has a portion already electrically coupled to a PCB, for example, by soldering, and also includes a plate 220a that is physically coupled to electrical connector 220, although it is shown separately in this exploded view. Electrical connector plate 220a provides a substantially flat coupling surface to which gasket 232 can be applied prior to assembly of device 200. Once gasket 232 is applied to electrical connector plate 220a, it can be pressed against the housing or coupled to another surface of the housing to create a seal around electrical connector 220 and the opening. Electrical connector plate 220a is then sealed to the electrical connector via the integral gasket. In this example, connector cover 222 is placed within the opening and pressed against gasket 232 to provide the seal. As a result, the gasket is pressed against the housing, gasket 230 (described in greater detail below), and the inner surface of connector cover 222 to seal the opening and complete the seal of device 200 .

[0055] As described above, gasket 232 is coupled to gasket 230 to provide a complete seal for device 200. Because gasket 230 has a gap corresponding to the opening, while there is some small overlap to provide a surface for gasket 232 to engage, it does not seal the opening. In addition, the opening is perpendicular to the plane of gasket 230 (or in some examples, at a different angle to the plane), complicating the sealing of the entire device 200. To achieve a complete seal, gasket 230 is pressed onto and engaged with gasket 232, such as with respect to the gasket 230. Figures 6A-6C Shown in detail.

[0056] In this example, as discussed above, the gasket 232 is applied to the electrical connector board 220a, and then the PCB 213 is placed in the housing portion 212 on the foam pad assembly discussed above (it should be understood that in some embodiments, the foam pad assembly is not required). The PCB 213 is then biased by an external force (e.g., a human finger or a robotically controlled tool) to press the electrical connector board 220a and the gasket 232 against the housing, helping to establish a seal between the gasket 232 and the housing. In examples where a connector cover is used, the external force can be applied at this time or at a later time.

[0057] Although PCB 213 is biased as discussed above, it uses Figure 2A213 is securely coupled to the housing portion 212 by the screws described in the foregoing. It should be understood that any suitable coupling technique can be used according to different examples to couple the PCB 213 to the housing portion 212 while maintaining the biasing force. By coupling the PCB 213 to the housing portion 212 while the PCB is biased, the biasing force of the gasket on the housing (or other surface) can be maintained even after the initial external biasing force is removed. The maintained biasing force can help maintain the seal between the gasket 232 and the opening. In addition to, or in lieu of, the biasing force, additional material, such as a potting compound, can be applied to the periphery of the opening or electrical connector to further enhance the seal of the opening.

[0058] Once the PCB 213 (and other internal components) are mounted within the housing portion(s) 210, 212, the gasket 230 can be applied to one of the coupling surfaces 210a, 212a and the two housing portions can be pressed together and secured using Figure 2A 2 and 3. The device 200 is physically coupled to the gasket 230 by the screws described in (or any other suitable coupling technique). The force applied by the screws provides a sealing force to compress the gasket 230 and establish a seal around the perimeter of the device 200. In addition, compressing the gasket 230 also presses it against the gasket 232, thereby completing the seal of the device 200. Thus, the device utilizes two gaskets that are orthogonal to each other and engage with each other to form a complete seal for the device to prevent the ingress of moisture or other contaminants.

[0059] It should be understood that Figure 2A-2B The specific size and shape of the components in FIG. 2 is an example of a device 200. Other examples according to the present disclosure may have different housing shapes and profiles. For example, while FIG. Figure 2A-2B A wearable wireless charging device is shown in FIG, but the device can be shaped or configured as a wristwatch, a continuous glucose monitor (“CGM”) or other wearable biosensor, an insulin pump, a smartphone or tablet device, etc. In addition, although the device 200 has a disc-shaped housing, other example devices can have other housing cross-sections, such as square, rectangular, triangular, etc., and thus can use gaskets corresponding to such housing shapes. For example, Figure 3 An example smartphone 300 is shown having a housing made of two housing parts 310, 320 having a rectangular shape, while providing an opening to accommodate an electrical connector 320, with Figure 2A-2B The device 200 shown is similar.

[0060] Furthermore, although the electrical connector 220 is positioned through an opening oriented substantially orthogonally to the gasket 230 of the sealed housing portions 210, 212, orthogonality is not required. Rather, the opening may be defined at any angle to the gasket 230 that may be suitable for a particular implementation. For example, Figure 4A cross section of a device 400 is shown, the housing of which is formed from two housing parts 410, 412, sealed by a gasket 430 which engages another gasket 432 which seals the opening at an oblique angle to the gasket 430. Figure 2A-2B and Figure 3 Similar to the device shown in , the opening provides access to the electrical connector 420. In addition, some examples may have multiple openings, each of which may be sealed by a corresponding gasket that engages with the gaskets of the two housing parts of the sealing device. For example, Figure 5 A smartwatch device with two openings (such as a charger and a 3.5 mm headphone jack) is shown to support two different electrical connectors. In other examples according to the present disclosure, further configurations may also be employed.

[0061] Now refer to Figures 6A-6C , Figures 6A-6C A cross-sectional view of an electronic device 600 is shown having an opening to accommodate an electrical connector 620 . Figure 6A 6 shows a cross section of the device 600 and illustrates the engagement of the device's perimeter gasket 630 and electrical connector gasket 632. Figure 6A as well as Figure 6B-6C As shown, electrical connector 620 is sealed to connector cover 622 by gasket 632. The peripheral gasket 630 is shaped to correspond to the coupling surface defined by housing portion 612 and includes portions, designated as protrusions 630a-b, that deviate from the circular shape of device 600 to instead correspond to the edges of the opening and engage with gasket 632. These protrusions 630a-b are integrally formed as part of the gasket, but are shaped as shown to engage with gasket 632 and the opening in the housing.

[0062] In addition, the size of the gasket protrusions 630a-b can be sized to engage with the electrical connector 620 itself. For example, the electrical connector 620 in this example has an O-ring 626 that surrounds the perimeter of the electrical connector 620 to achieve a seal within the electrical connector itself. The shape of the protrusions 630a-b enables the gasket 630 to engage with the O-ring to provide a further seal. Thus, the device has a first seal established by the gasket 630 between the housing portions of the device, a second seal established by the gasket 632 around the opening, a third seal between the gaskets 630 and 632, and a fourth seal between the gasket 630 and the O-ring 626. The establishment of these multiple seals may help further seal the device from moisture (or other contaminants).

[0063] Figure 7A-7BAnother example device 700 according to the present disclosure is shown. However, in this example, rather than using two different gaskets, the device is sealed by a single gasket 730. Similar to some other example devices according to the present disclosure, the device 700 has a housing formed of two housing portions 710, 720 that are coupled together. In addition, the housing forms an opening to allow access to an electrical connector 720.

[0064] As described above, the gasket 730 is placed between the two housing sections 710, 712 to engage with a sealing surface formed on each housing section 710, 712. When the housing sections 710, 712 are coupled together, they compress the gasket 730, forming a seal between the housing sections 710, 712. However, as Figure 7B As shown, gasket 730 is formed to have a peripheral portion 730a and an opening portion 730b. Peripheral portion 730a seals housing portions 710, 712 to each other, while opening portion 730b seals housing portions 710, 712 to electrical connector 730 and seals electrical connector 730 within the opening. Thus, gasket 730 integrates two gaskets, such as gaskets 230 and 232, into a single gasket to seal the entire device. As with the gaskets discussed above, gasket 730 can be constructed of any suitable material, such as a foam material, with each side coated with a PSA to help align gasket 730 with the housing portions and seal device 700.

[0065] Figure 7A-7B The gasket shown in FIG can simplify the manufacturing process of some example devices because only a single gasket is required. Therefore, the mutual alignment and engagement of two different gaskets is avoided. However, the manufacture of the gasket 730 itself may be more complicated.

[0066] Now refer to Figures 8A-8C , Figure 8A An example gasket 830 is shown that can be used to seal a wearable electronic device according to the present disclosure. In this example, similar to Figure 7B In the example shown, the gasket 830 is formed from a single piece of material and is suitable for sealing the housing portions to each other and the electrical connector, such as the electrical connector 720, to the housing. The gasket 830 has a peripheral portion 830a and an opening portion 830b. As with the example gaskets illustrated in the figures and discussed above, the gasket 830 is shaped to correspond to the peripheral shape of the wearable device. In this example, the peripheral portion 830a is shaped to correspond to the peripheral shape of the wearable device. Figure 7A The periphery of the device 700 is shown in FIG. The opening portion 730b is shaped to correspond to the shape of the opening and to mate with the electrical connector 720 and the housing.

[0067] In this example, the gasket is formed from a single piece of material, eg, via laser cutting, stamping, etc., and is configured to be folded to create the open portion 830b. Figure 8C The folded case is shown with the opening portion folded to a plane orthogonal to the plane of the perimeter portion 830a. However, as discussed above, the relationship between the two gasket portions need not be orthogonal, but may instead have an oblique alignment, such as Figure 4 As shown. Furthermore, in this example, the gasket material has a PSA applied to each side of the material, enabling the folded portions of the opening portion 830 to seal against each other and to adhere to and maintain position against the housing portion or against the electrical connector during assembly of the device 700. However, in some examples, the PSA may be applied to the housing portion instead of, or in addition to, the gasket itself. Such techniques are equally applicable to each of the example gaskets discussed herein.

[0068] according to Figures 8A-8C The example shims 830 shown may be advantageous because they may be relatively simple to form by cutting the shims from a single sheet of material, rather than using a molding process ( Figure 7B The examples shown may require ).

[0069] As discussed above, although Figure 7A-7B and Figures 8A-8C The example device 700 and spacers 730, 830 are shown as having particular shapes and sizes, but each may have any suitable size and shape, such as those described above with respect to FIG. Figure 3-Figure 5 Discuss the size and shape. In addition, although Figure 7A-7B and Figures 8A-8C The gaskets 730, 830 shown in FIG. 7 each have only one opening portion 730b, but some examples may include multiple opening portions to accommodate multiple openings defined in a device housing, such as Figure 5 As shown in .

[0070] Now refer to Figure 9 , Figure 9 An example method 900 for sealing a wearable electronic device is shown. Figure 2A-2B The example method 900 is discussed with respect to the example device 200 shown in FIG. 9 ; however, example methods according to the present disclosure may be employed with respect to any suitable device according to the present disclosure.

[0071] At block 910, first and second housing portions 210, 212 are obtained and provided to an assembly process. In this example, the housing portions 210, 212 have circular shapes and together form a housing having a disc shape. However, it should be understood that any suitable housing shape may be employed, such as the housing portions described above with respect to FIG. Figure 3-Figure 5Furthermore, the device housing may be composed of a number of different components. For example, Figure 2A 2, the housing has a generally rectangular plate that is affixed to the cavity formed in the housing portion 210. Such a plate may cover other openings in the housing, such as for a speaker or one or more light emitters, such as one or more light emitting diodes ("LEDs"). However, the housing portions 210, 212 form the portion of the housing that protects the electronics placed on the PCB 213 in this example, and are the housing portions 210, 212 sealed by the perimeter gasket 230 and the opening gasket 232, even if other gasket seals are used, such as to seal the openings for the speaker or one or more LEDs.

[0072] At block 920, the gasket 230 is coupled to one of the first or second housing portions. Figure 2A As discussed, each housing portion 210, 212 defines a coupling surface 210a, 212a. When the housing portions 210, 212 are coupled to one another, these coupling surfaces will interconnect and engage. Thus, in this example, the gasket 230 is coupled to one of the coupling surfaces 210a, 212a, for example, using a PSA applied to the gasket material or one of the coupling surfaces. In some examples, the gasket 230 can simply be placed in position on one of the coupling surfaces without using any adhesive or similar coupling mechanism. For example, the coupling surface 212a may be recessed below the periphery of the housing portion 212, and thus, the gasket 230 can simply be placed on the recessed coupling surface 212a, where it can be held in place within the recess. Still other methods of placing or coupling the gasket 230 to one of the housing portions 210, 212 may also be employed.

[0073] At block 930, the second pad 232 is coupled to the electrical connector plate 220a of the electrical connector 220, which is electrically coupled to the PCB 213 and is to be placed within the housing. Figure 2A As shown, electrical connector 220 has a connector plate 220a coupled thereto, and gasket 232 is coupled to connector plate 220a via a PSA coated on the gasket material. However, a PSA is not required. In some examples, the gasket can be pressed against a flange on the connector plate that holds the gasket in place until device 200 is fully assembled.

[0074] At block 940, the PCB 213 is placed within one of the housing portions 210, 212, and a biasing force is applied to the PCB 213 to press it toward the partial opening 214, 216, which can engage the gasket 232 with the housing portions 210, 212, or otherwise position the electrical connector board 220a and gasket 232 to establish a seal around the opening. In this example, the PCB 213 is coupled to a foam pad via a PSA, and the foam pad is coupled to the housing portion 212 via another PSA. Once this assembly is in place within the housing portion 212, a biasing force is applied. It should be understood that a biasing force is not required in every example according to the present disclosure. Rather, it may be employed in some examples to help provide a secure seal for the opening. However, in some examples, the position of the PCB and the electrical connector board 220a may be sufficient to seal the opening without the need for an additional biasing force. For example, as described above with respect to Figures 6A-6C As discussed, the electrical connector 620 can include an O-ring 626 that surrounds a portion of the outer periphery of the electrical connector 620. This O-ring 626 can engage with the perimeter gasket 620, which can help seal the device. In such an example, a biasing force may not be required because the opening gasket can seal the opening by engaging with the housing, and the O-ring can further supplement the seal provided by the opening gasket by engaging with the perimeter gasket 620. Furthermore, in some examples, an additional sealing material, such as a potting compound, can be applied to the perimeter of the electrical connector to further seal the opening from moisture ingress.

[0075] At block 950, the PCB 213 is physically coupled to the housing to hold it in place and, if a biasing force is applied, to maintain that biasing force. In examples where a biasing force is applied, this may cause the foam pad on which the PCB 213 is located to deflect. If the PCB 213 is not coupled by an additional mechanism, the PCB 213 may return to an unbiased position when the biasing force is removed. Therefore, in this example, screws are used to physically secure the PCB 213 to the housing portion 212. The screws can then maintain the biasing force on the PCB 213 and maintain the seal at the opening. If a biasing force is not required, a PSA may be sufficient to couple the PCB 213 to the housing portion; however, screws or rivets or other coupling mechanisms may also be used.

[0076] At block 960 , the two housing portions 210 , 212 are pressed together to apply a sealing force to the gasket 230 and coupled together, such as by using screws, rivets, or the like.

[0077] At block 970, the opening gasket 232 is engaged with the other housing portion 210, 212 (e.g., the housing portion other than the housing portion to which the PCB 213 is coupled) and, if not already engaged, with the perimeter gasket 230, e.g., when the perimeter gasket 230 is initially coupled to the other housing portion 212 while the PCB 213 is attached to one housing portion 210. Additionally, if an additional component (e.g., a connector cover 222) is used to seal the opening, it is pressed into position within the opening to complete the sealing of the opening. After performing the coupling and engagement discussed with respect to block 970, the seal between the two housing portions 210, 212 is complete, as is the seal of the electrical connector at the opening.

[0078] It should be understood that the order of the blocks in the example method 900 described above is not required and other orders may be used. For example, blocks 920-950 may be performed in a different order, such as by first placing the PCB 213 within the housing portion 212, then applying the gasket 232 to the electrical connector 220, and then applying the perimeter gasket to one of the housing portions 210, 212.

[0079] Furthermore, it should be understood that the example method 900 may not be sufficient to fully assemble the device 200. Other steps may also be taken, such as applying a cover, such as one with a logo or product name, to the housing, or inserting other components into the housing before it is sealed.

[0080] Now refer to Figure 10 , Figure 10 Another example method 1000 for sealing a wearable electronic device is shown. Figure 7A-7B The example method 900 is discussed with respect to the example device 700 shown in FIG. 9 ; however, example methods according to the present disclosure may be employed with respect to any suitable device according to the present disclosure.

[0081] At block 1010 , first and second housing portions 710 , 712 are obtained and provided to an assembly process, generally as discussed above with respect to block 910 .

[0082] At block 1020, the gasket 730 is coupled to one of the first or second housing portions, generally as discussed above with respect to block 920. However, in this case, because the gasket 730 includes an opening portion 730b, the opening portion of the gasket 730b is positioned within the partial opening of the corresponding housing portion 710, 712.

[0083] At block 1030, the electrical connector 720 electrically coupled to the electrical connector cover of the PCB attached to the electrical connector is inserted into the opening portion 730b of the gasket 730, and the gasket 730 is engaged with the electrical connector 720, for example, with the electrical connector plate portion of the electrical connector, as generally discussed above. It should be understood that block 1030 can be performed before block 1020 so that the electrical connector 720 is engaged with the gasket 730 before the gasket 730 is placed on one of the housing portions 710, 712.

[0084] At block 1040, the PCB is placed within one of the housing portions 710, 712, and a biasing force is applied to the PCB, generally as discussed above with respect to block 940. However, similar to the above with respect to Figure 9

[0066] The examples discussed, in some examples, do not require the use of a biasing force.

[0085] At block 1050 , the PCB is physically coupled to one of the housing portions 710 , 712 , generally as discussed above with respect to block 950 .

[0086] At block 1060 , the two housing portions 710 , 712 are pressed together to apply a sealing force to the gasket 730 and are coupled together, generally as discussed above with respect to block 970 .

[0087] Now refer to Figures 11A-11B , Figure 11A An example system for dynamically controlling near-field wireless power is shown. System 1100 in FIG11 includes two wireless devices 1110 and 1120. Wireless device 1110 will be referred to as a charger device 1110, although this does not imply that charger device 1110 (or any other "charger device" according to the present disclosure) is only suitable for use as a battery charger. Rather, charger device 1110 is capable of generating an EMF that can be used to provide power to another wireless device 1120, which will be referred to as a target device 1120.

[0088] from Figure 11AAs can be seen in the figure, charger device 1110 includes a transmitting antenna coil 1112. Charger device 1110 transmits current through transmitting antenna coil 1112, generating EMF 1130. To power target device 1120, charger 1110 is brought near target device 1120 and generates EMF 1130. Although depicted as a signal transmitted to target device 1120, it is actually a field surrounding charger device 1110. Target device 1120 is placed within this field. The target device's receiving antenna coil 1122 then couples with EMF 1130 to receive power. Furthermore, charger device 1110 employs a second antenna coil—receiving antenna coil 1114—which also receives power from EMF 1130.

[0089] In this example, the receive antenna coil 1114 is placed concentrically with the transmit antenna coil 1112. Such an arrangement may provide more efficient coupling between the receive antenna coil 1114 and the EMF 1130; however, it should be understood that the transmit and receive antenna coils 1112, 1114 need not be concentrically arranged about a common axis.

[0090] refer to Figure 11B , Figure 11B A cross-section of the charger device 1110 is shown to illustrate the arrangement of the transmit and receive antenna coils 1112, 1114. In this example, while the two antenna coils 1112, 1114 are concentrically arranged, they are not coplanar. Specifically, in this example, the transmit antenna coil 1112 is placed on one side of a printed circuit board ("PCB"), while the receive antenna coil 1114 is placed on the other side of the PCB, all of which are placed within the housing 1115 of the wireless device. Such an arrangement may be used due to the placement of other electronic components on the PCB. However, it should be understood that in some examples, the two antenna coils 1112, 1114 can be coplanar. Furthermore, whether the two antenna coils 1112, 1114 are concentrically arranged is independent of whether they are coplanar with respect to each other.

[0091] Now refer to Figure 12 , Figure 12 An exploded view of an example charger device 1200 for dynamically controlling near-field wireless power is shown. Figure 12The example charger device 1200 shown in FIG. 1 includes two housing portions: an upper housing 1210 and a lower housing 1212. Housed within the housing is a PCB 1220, coupled to which are a transmit antenna coil 1222 and a receive antenna coil 1224, which are formed as traces on the PCB 1220. As can be seen, the transmit and receive antenna coils 1222, 1224 are concentrically aligned but not coplanar. The PCB 1220 also has several electronic components coupled thereto, including a processor, a wireless field driver, and an EMF sensor. A battery 1230 is included to power the electronic components and to provide current to generate the EMF, thereby transferring power to the target device.

[0092] Now refer to Figure 13 , Figure 13 An example wireless device 1300 for dynamically controlling near-field wireless power is shown. In this example, the charger device 1300 includes a wireless field driver 1320 and an EMF sensor 1330, both connected to a processor 1310. The wireless field driver 1320 is configured to generate an EMF in response to commands from the processor 1310. To do this, the wireless field driver 1320 includes a current source 1322 and a transmit antenna coil 1324.

[0093] In this example, the current source 1322 is a switching power amplifier, such as a high efficiency switching amplifier. An example of such a switching power supply is shown below with respect to Figure 15-17 Advantages of using such a power supply may include real-time adjustment of the power amplifier to reduce power consumption while maintaining a target EMF strength. However, it should be understood that any suitable variable alternating current ("AC") power source may be employed to generate and deliver alternating current to the transmit antenna coil 1324. In response to such current, the transmit antenna coil 1324 generates a signal that can be used to deliver power to a target device, such as a Figure 11A The target device 1120 shown in FIG. 1 provides the alternating EMF of the power.

[0094] In this example, the EMF sensor 1330 includes a receiving antenna coil 1331, which couples to the EMF generated by the wireless field driver 1320 and outputs an AC signal based on the strength of the field. The receiving antenna coil 1331 is electrically coupled to a peak detector 1333 and a zero-crossing detector 1335. The output of the peak detector 1333 is electrically coupled to the processor 1310, providing a signal indicating the EMF amplitude. The zero-crossing detector 1335 is coupled to a phase detector 1337, which receives the output from the zero-crossing detector 1335 and a reference signal 1339 to detect phase changes in the EMF. The output of the phase detector is electrically coupled to the processor 1310, transmitting a signal indicating information regarding the EMF phase.

[0095] Regarding peak detector 1333, any suitable peak detector may be employed. For example, a simple peak detector may be implemented by connecting a diode in series with a capacitor coupled to receive antenna coil 1214. The voltage across the capacitor will then indicate the amplitude of the AC signal. However, depending on the application, a more complex peak detector may be employed.

[0096] Any suitable zero-crossing detector, such as a commercially available semiconductor zero-crossing detector device, can be used with respect to zero-crossing detector 1335. Alternatively, a suitable circuit, such as a comparator coupled to receive antenna coil 1214, can be used. The output of zero-crossing detector 1335 is provided to phase detector 1337, which also receives reference signal 1339, for example, based on an AC signal output by a current source. Phase detector 1337 then detects the phase difference between the output signal from the zero-crossing detector and the reference signal. In this example, the output of phase detector 1337 is a voltage indicating the phase difference between the zero-crossing detector signal and the reference signal, and is provided to processor 1310 to indicate the phase change of the generated EMF.

[0097] In this example, processor 1310 is a microcontroller that executes processor-executable instructions stored in a memory (not shown) to receive the peak detector signal to estimate the strength of the EMF; however, it should be understood that any suitable processor, including an application-specific integrated circuit ("ASIC"), may be used. Processor 1310 also uses the phase detector signal to estimate the load impedance of the target device to detect foreign objects located between charger device 1300 and the target device, or such objects in close proximity to charger device 1300. It can also determine potential harmful EMI effects and reduce the strength of the EMF accordingly.

[0098] In response to receiving the peak detector signal, the processor 1310 estimates the intensity of the EMF and determines the difference between it and the target intensity of the EMF. If the estimated intensity is different from the target intensity, the processor 1310 increases or decreases the amount of current output by the current source 1322 to adjust the intensity of the EMF. By iteratively adjusting the output current of the current source, the processor 1310 is able to adjust the intensity of the EMF until it matches the target EMF intensity or is within a threshold amount of the target EMF intensity. Figure 14 Example techniques for iteratively adjusting output current are discussed.

[0099] In response to receiving the phase signal from the phase detector, processor 1310 can estimate the load impedance presented by the target wireless device. The estimated load impedance can be used to tune and adjust the duty cycle of current source 1322 to better match the load impedance. Alternatively, or additionally, the target device can adjust its load impedance, for example, by activating and deactivating electronic functions, to convey information to charger device 1300. For example, the target device can adjust its presented impedance to output data at a fixed bit rate (e.g., 1 bit per millisecond), which can be detected by phase shift changes detected by the phase detector. This data transmission technique can be used to provide information about the status of the target device, such as estimated received EMF strength, estimated received power, estimated power requirements, battery charge level, etc. This information can then be used to adjust the EMF strength.

[0100] For example, processor 1310 can determine a difference between an estimated EMF strength determined by charger device 1300 and an estimated EMF strength received from a target device. This difference can indicate the distance between the charger device and the target device and can be used to scale the target EMF strength based on the decrease in signal strength with distance according to an inverse square relationship. In some examples, an estimated power requirement received from the target device can be used to adjust the target EMF strength based on the difference between the estimated EMF strength determined by the charger device (or target device) and the estimated power requirement.

[0101] Now refer to Figure 14 , Figure 14 It is shown that the processor of the charger device may be used, for example Figure 13 14. The example technique for dynamically controlling near-field wireless power employed by the processor 1310 shown in FIG. In this example, the technique employs a PID control system 1400 to adjust the output current of a wireless field driver 1430. The control system 1400 accepts a target EMF intensity 1410 as an input signal and an output of an EMF sensor 1440, e.g., Figure 13 The output of the peak detector 1333 is used as the error signal. The input and error signals are summed to produce an error, which is provided to each of the P, I, and D sections of the PID controller. The outputs of these three blocks are summed to provide an adjusted control signal to the wireless field driver, which adjusts the amount of current output to the transmit antenna coil. The sum of these three terms can be expressed as follows:

[0102]

[0103] where K p , K i and K dThe terms represent the coefficients of the P, I, and D terms, respectively, and the function e(t) represents the time-varying error signal. Adjusting the coefficients changes the control system's response to the detected error, depending on the desired convergence time, allowable overshoot, and so on. For example, a suitable transfer function can be designed based on the desired pole and zero locations.

[0104] Figure 14 The illustrated technique 1400 also includes a saturation function 1420 that applies a saturation limit to the output from the PID controller to limit the maximum output current or to limit the rate of change of the output current. For example, if the output of the PID controller exceeds a threshold, the saturation function 1420 may output a fixed saturation value. For example, if the PID controller outputs a signal indicating a current of 300 mA, and the current source is only capable of outputting a maximum of 100 mA, the saturation function 1420 may output a signal to cause the current source to output a current of 95 mA (or other value).

[0105] Figure 14 The PID controller shown in FIG operates iteratively over time to vary the current output by the wireless field driver, thereby adjusting the strength of the EMF generated by the transmitting antenna coil. In successive iterations, the PID controller causes the estimated strength of the generated EMF to converge to a target EMF strength, as long as the wireless field driver is able to output a sufficiently strong EMF.

[0106] It should be understood that although this example employs a PID controller, one or both of the P, I, or D terms can be eliminated to provide a desired control system, such as a PI or PD control system. Such alternative control system approaches may be suitable for different implementations, depending on the complexity or design requirements of the system.

[0107] Now refer to Figure 15 , Figure 15An example adjustable power amplifier suitable for use with an example system for dynamically controlling near-field wireless power is shown. Example system 1500 includes a DC / DC power supply 1510 with a selectable output voltage, as discussed above with respect to FIG. It should be understood that any suitable DC power supply with an adjustable DC output voltage can be used as power supply 1510, including an adjustable AC / DC power supply. The power amplifier includes two MOSFETs M1-M2 arranged as switches in a half-bridge configuration. A PWM gate driver 1520 is connected to the gates of each of MOSFETs M1-M2 and toggles the gates to switch them on and off. PWM gate driver 1520 maintains MOSFETs M1-M2 in opposite states, such that M1 is in the opposite state to M2, operating them in ZVS and ZCS modes. PWM gate driver 1520 switches the switches according to a duty cycle selected by a controller (not shown) to provide an output signal to a tank circuit 1540, which, in combination with a low-pass filter 1550, provides an impedance conversion network. The output of the low-pass filter 1550 is provided to a load 1560, which includes a transmitting coil L7 and a receiving coil and circuit, and a resistor R l The controller 1570 provides a duty cycle selection signal to the PWM gate driver 1520 and a voltage selection signal to the DC / DC converter 1510 .

[0108] In this example, each MOSFET M1-M2 has a respective diode D1-D2 coupled between its source and drain to circulate power through the respective MOSFET M1-M2, thereby enabling the power amplifier to accommodate a greater amount of load reactance. Schottky diodes with a low voltage drop can be employed as D1-D2 to provide efficient energy recycling, although other types of diodes may be employed according to some examples. Furthermore, while the MOSFETs M1-M2 operate substantially in ZVS and ZCS modes, variations in load reactance may result in ZVS and ZCS conditions not being met across the entire load reactance range, although this configuration may still reduce power dissipation across the entire load reactance range.

[0109] Tank circuit 1540 is configured to operate in a resonant manner at the desired transmission frequency, such as by providing a substantially zero ohm resistance at resonance, or it can be configured to provide a predetermined impedance shift away from the resonant frequency. Filter 1550 is used to provide low-pass filtering of the power amplifier output and to convert the load impedance range to a predetermined impedance range for presentation to power amplifier 1530. The load impedance range can then be used by controller 1570 to select a duty cycle for PWM gate driver 1520.

[0110] For example, reference Figure 16 , Figure 16 A graph 1600 is shown of duty cycles that achieve high efficiency at a target impedance in an impedance plane, where the x-axis represents resistance and the y-axis represents reactance. As can be seen, curve 1610 represents the corresponding relationship between duty cycle (normalized to a range of 0 to 1) and load impedance. Points on curve 1610 represent duty cycles for a particular impedance that provide the best power transfer efficiency for the power amplifier at that impedance. Deviations from curve 1610, such as due to limitations of the tank circuit and filter 1550, may result in reduced efficiency of power transfer, however, as with respect to Figure 17 As can be seen, an approximation close to curve 1610 can still provide relatively efficient power transfer. The design of the circuit may affect the range of impedance within which the power supply 1510 can effectively transfer power to the target device. For example, a relatively simple impedance transformation network including Figure 15 Filter 1550, shown in FIG, can approximate curve 1610 over a small impedance range before deviating significantly. More complex impedance transformation networks can be designed to allow the power supply to approximate curve 1610 over a wider range of load impedances, although such impedance transformation networks may require more physical layout space.

[0111] The filter 1550 in this example uses capacitor C5 and inductor L9 and is Figure 17 The load inductance range shown provides Figure 16 16. In this example, C3 has a value of 26.3 nanofarads ("nF") and the inductor has a value of 350 nanohenries ("nH"). The filter 1550 employs a capacitor C5 having a value of 5.2 nF and an inductor L9 having a value of 94 nH. Using these circuit components, the power amplifier follows Figure 17 17. As can be seen, approximation curve 1710 closely matches curve 1610 across a load impedance range of approximately 1 to 3 ohms before beginning to deviate. Thus, power supply 1510 is able to efficiently transfer power despite the load impedance increasing or decreasing by 50% from a midpoint load impedance of 2 ohms by varying the PWM duty cycle between 0.38 and 0.43.

[0112] Reference again Figure 15 In addition to adjusting the duty cycle setting of the PWM gate driver 1520, the controller 1570 adjusts the output of the power supply 1510 based on the PWM duty cycle. Figure 18 , Figure 18Two curves 1810 and 1820 are shown, representing the current (y-axis) provided by the power supply to the transmitting coil L7 across a range of duty cycles (x-axis) at a specific voltage. In this example, the upper curve 1810 represents the output at 10 volts, while the lower curve 1820 represents the output at 5 volts. Therefore, based on the amount of current to be supplied to the transmitting coil L7, the voltage output by the DC / DC converter 1510 is adjusted based on the duty cycle. In this example, a decrease in the duty cycle corresponds to an increase in the voltage output of the DC / DC converter 1510. For example, for a duty cycle change from 0.43 to 0.39, in order to maintain a current of approximately 0.4 amperes, the output of the DC / DC converter will increase from approximately 5 volts to approximately 10 volts. Therefore, Figure 18 Represents a portion of a three-dimensional surface, where the X-axis represents the duty cycle, the Y-axis represents the transmit coil current, and the Z-axis represents the DC / DC converter output voltage. Using such a surface, a combination of duty cycle and current can be used to select the DC / DC converter output voltage. Thus, in some examples, the lookup table can be a two-dimensional array.

[0113] Now refer to Figure 19 , Figure 19 An example system 1900 for dynamically controlling near-field wireless power is shown. Figure 11A In the example shown in FIG, system 1900 includes a charger device 1910 and a target device 1920. The charger device 1910 includes a transmitting antenna coil 1912 and a receiving antenna coil 1914; however, unlike Figure 11A Unlike the example shown, the two antenna coils 1912 and 1914 in charger device 1910 are not concentrically aligned. In this example, they are coplanar; however, in some examples, they may not be in the same plane; for example, they may be placed on opposite sides of a PCB. Therefore, different arrangements of transmit and receive coils 1912 and 1914 may be used according to different examples.

[0114] Now refer to Figure 20 , Figure 20 Another example system 2000 for dynamically controlling near-field wireless power is shown. In this example, the charger device 2010 and the target device 2020 are similar to Figure 11A, however, each also includes Bluetooth ("BT") communication capabilities, such as BT Low Energy ("BLE"). As discussed above, in some examples, the target device 2020 can modify the load impedance it presents by activating and deactivating electronic components within the target device 2020. By doing so, it can communicate information to the charger device 2010, which will detect the changing load impedance as a phase change in the generated EMF. However, in this example, the two devices 2010, 2020 can instead communicate such feedback information via a BT or BLE connection.

[0115] For example, the charger device 2010 can generate EMF 2030 to provide electrical energy to the target device 2020, which can use the energy to power various components of the device (including the BT or BLE subsystem). The two devices can then pair using BT or BLE communication technology, and the target device 2020 can transmit feedback information, such as estimated received EMF strength, estimated received power, estimated power requirements, etc., to the charger device 2010. The charger device 2010 can then adjust the strength of the EMF 2030 based on such information, as described above and below with respect to Figure 21-22 As will be described.

[0116] Now refer to Figure 21 , Figure 21 An example method 2100 for dynamically controlling near-field wireless power is shown. The example method 2100 will be relative to Figure 13-14 However, any suitable system, device, or technique consistent with the present disclosure may be employed.

[0117] At block 2110, the charger device 1300 causes the current source to output current to the transmit antenna coil to generate an EMF. In this example, the processor 1310 outputs a signal to the current source 1322 to activate the current source 1322 so that it outputs AC current to the transmit antenna coil 1324. The current source 1322 in this example is a switching power amplifier, such as Figure 15 The current source 1322 outputs AC current at a predetermined frequency and a predetermined default current amount.

[0118] At block 2120, processor 1310 receives one or more signals from EMF sensor 1330. In this example, processor 1310 receives an amplitude signal from peak detector 1333, which indicates the peak amplitude of the received EMF. As discussed above, EMF sensor 1330 utilizes receiving antenna coil 1331 to receive electrical energy from the EMF generated by wireless field driver 1320. This received electrical energy is then transferred to peak detector 1333. Peak detector 1333 receives the signal from receiving antenna coil 1331 and outputs a signal indicating the maximum amplitude of the received EMF. It should be understood that while the signal output by peak detector 1333 in this example is an analog voltage signal, in some examples, peak detector 1333 may output a digital value indicating the maximum amplitude of the received EMF. For example, peak detector 1333 may utilize an analog-to-digital converter to generate a digital representation of the maximum amplitude. In some examples, the output of peak detector 1333 may be a DC signal, though it should be understood that this signal may vary based on the strength of the EMF.

[0119] In addition to the amplitude signal, in this example, processor 1310 also receives a phase signal from phase detector 1337. The phase signal indicates the phase difference between the received EMF and reference signal 1339. In this example, reference signal 1339 is output at the same frequency and phase as the AC current output by current source 1322. In some examples, reference signal 1339 may be output by current source 1322 itself. As discussed above, phase detector 1337 receives a signal (e.g., a square wave) and the reference signal from zero-crossing detector 1335. If reference signal 1339 is output by current source 1322, it may be converted to a square wave if it was not originally output as a square wave. Any phase shift in the received EMF results in periods of unequal voltages (or currents) of the two signals. The duration of these differences in the frequencies of the two signals indicates the amount of phase shift. Phase detector 1337 detects the difference in these values, for example using a comparator, and outputs a signal indicating the phase difference to processor 1310.

[0120] It should be understood that the phase detection function may be omitted in some examples. Although phase information may be used for various functions, estimating the strength of the generated EMF is not necessary and may be omitted.

[0121] At block 2130, processor 1310 determines the strength of the generated EMF. In this example, processor 1310 receives the amplitude signal from peak detector 1333 and determines the strength of the generated EMF based on the amplitude signal. In this example, processor 1310 utilizes a lookup table that correlates peak signal values, such as voltage, with EMF strength. However, in some examples, processor 1310 may calculate an estimated EMF strength using Faraday's law based on the amplitude signal and characteristics of the wireless field generator, such as the transmit antenna coil (e.g., number of turns) and the amount of current output by current source 1222.

[0122] At block 2140, the processor 1310 determines the load impedance of the target device. In this example, the processor 1310 determines the load impedance of the target device based on the phase difference output by the phase detector 1337. In this example, the processor 1310 employs a lookup table that relates phase shift to load impedance.

[0123] At block 2150, the processor 1310 adjusts the current source to adjust the amount of current output by the wireless field driver to adjust the intensity of the generated EMF. For example, the processor 1310 may adjust the amount of current based on feedback information from the EMF sensor 1330 to maintain the power characteristics of the generated EMF. Such power characteristics may be the amplitude of the generated EMF, the frequency of the generated EMF, the phase of the generated EMF, etc. Such power characteristics may be further maintained or adjusted based on load impedance measurements, changes in the power requirements of the remote device, etc. For example, as described above with respect to Figure 14 As discussed, the processor 1310 may implement a PID controller (or other feedback control system) to regulate the output current of the wireless field driver 1320 .

[0124] At block 2160, the processor 1310 adjusts the operating parameters of the current source. In this example, the charger device 1300 employs a tunable switching power amplifier, such as Figure 15 To adjust the operating parameters, the processor 1310 may be configured as described above with respect to Figure 15-17 The output voltage of the DC power supply or the duty cycle of the PWM gate driver 1520 is adjusted based on the load impedance estimated at block 2140 as discussed.

[0125] In some examples, processor 1310 can adjust the output voltage or duty cycle of the power amplifier to reduce power consumption. For example, processor 1310 can cause a current source to output a constant current while adjusting the duty cycle of a PWM gate driver. The amount of power consumed by the current source can then be measured and provided to processor 1310. Processor 1310 can then vary the duty cycle across a range of values and determine the duty cycle that minimizes power consumption for the tested duty cycles.

[0126] At block 2170, the processor 1310 may detect one or more foreign objects. In one example, the processor 1310 may compare the estimated load impedance to one or more thresholds to determine whether the load impedance is within an expected range or is above (or below) an expected value. If the estimated load impedance falls outside the expected range or does not meet the expected threshold, the processor 1310 may determine that a foreign object is present and interfering with the generated EMF.

[0127] At block 2180, the processor 1310 may determine one or more voltage or current harmonics within the generated EMF. For example, the processor 1310 may implement a fast Fourier transform to obtain a spectral representation of the EMF. The processor 1310 may then identify one or more peak frequencies in the spectral representation to identify one or more harmonics. Alternatively, the processor 1310 may implement one or more bandpass filters configured to isolate one or more predetermined frequencies, or may be in communication with one or more bandpass filters. The processor 1310 may then determine the strength of the signal output by the filter(s) and compare the strength of the signal to one or more thresholds to determine whether harmonic frequencies are present. If one or more harmonics are detected, it may indicate that the charger device 1300 is causing harmful interference. Therefore, the processor 1310 may reduce the strength of the generated EMF until the strength of the detected harmonics falls below a predetermined threshold. To reduce the strength of the generated EMF, the processor 1310 may implement a second PID controller (or other suitable feedback controller), similar to Figure 15 ; however, the error signal may be the strength of the harmonic(s), and the target signal may be a threshold maximum tolerable harmonic strength.

[0128] It should be understood that some harmonics, such as high-frequency harmonics in the gigahertz range, may not be measured directly. Instead, the processor may indirectly detect such harmonics based on the presence of low-frequency harmonics, such as those in the range below 100 MHz. The processor may then determine an estimated amplitude of one or more high-frequency harmonics, or determine whether an estimated amplitude of a high-frequency harmonic may exceed a threshold amplitude, for example, based on the amplitude of a low-frequency harmonic exceeding the threshold.

[0129] Additionally, the processor can detect the presence of such harmonics (e.g., by detecting a threshold power level at one or more predetermined harmonic frequencies) and then, based on the absence of such harmonics with a threshold amount of phase shift, can determine the presence of a foreign object, as a continuation of the functionality discussed above with respect to block 2170.

[0130] At block 2190, processor 1310 may obtain information output by the target device. For example, as discussed above, the target device may modulate its load impedance by activating and deactivating electronic functions to transmit digital data via the generated EMF. This change in load impedance may be detected by phase detector 1337. By detecting the change between two different load impedances, processor 1310 may detect a binary value output at a predetermined bit rate. For example, if the target device modulates its load impedance once per millisecond, processor 1310 may sample the phase information once per millisecond to obtain a single bit. For example, if the phase shifts between two values, one value may represent a binary "1" and the other may represent a binary "0." Thus, processor 1310 may obtain a series of such binary values to obtain feedback information from the target device, such as expected power requirements, battery power level, etc.

[0131] Although Figure 21 The method is described as including certain features performed in a particular order, but it should be understood that any of blocks 2130-2190 may be performed in any suitable order. For example, the processor 1310 may determine the load impedance at block 2140 before determining the intensity of the EMF. Similarly, Figure 21 One or more of the blocks shown in are optional. For example, in some examples, one or more of block 2140 and blocks 2160-2190 can be omitted. In some examples, blocks 2130 and block 2150 can be omitted. Thus, different example methods can provide different functionality related to controlling EMF, information about the status of a target device, information about nearby foreign objects, or harmful EMI.

[0132] Now refer to Figure 22 , Figure 22 Provides a method for controlling a power amplifier such as Figure 15 Although it should be understood that any suitable power amplifier may be used.

[0133] At block 2210, the controller 1570 receives an indication of the load impedance from the impedance sensor 2260. In this example, the controller 1570 receives a voltage signal corresponding to the load impedance from the impedance sensor 2260. However, in some examples, the controller 1570 may receive a current signal, a PWM signal, or a digital value indicating the load impedance. Any other suitable impedance sensor may also be employed.

[0134] At block 2220, the controller 1570 determines a duty cycle based on the load impedance. In this example, the controller 1570 accesses a lookup table stored in memory and determines a duty cycle corresponding to the load impedance. However, in some examples, the controller 1570 may determine the duty cycle based on the load impedance and a mapping function stored in memory. For example, the mapping function may include one or more polynomial functions that map the load impedance to the duty cycle, such as those described above with respect to FIG. Figures 11A-11B described.

[0135] At block 2230, the controller 1570 determines the supply voltage based on the determined duty cycle. In this example, the controller 1570 accesses a lookup table and determines the supply voltage corresponding to the determined duty cycle. However, in some examples, the controller may determine the supply voltage based on the duty cycle and a mapping function. For example, the mapping function may include one or more polynomial functions that map the duty cycle to the supply voltage, such as those described above with respect to FIG. Figures 11A-11B described.

[0136] At block 2240, the controller 1570 transmits a signal to the DC / DC converter 1510 to adjust its output voltage based on the determined supply voltage. In this example, the signal is a voltage signal indicative of the determined supply voltage; however, any suitable signal may be provided, including a current signal, a digital value indicating an output voltage selection, a PWM signal, etc.

[0137] At block 2250, the controller 1570 transmits the determined duty cycle to the power amplifier 1530. In this example, the controller 1570 transmits a voltage signal to a PWM gate controller, such as the PWM gate controller 1520, to establish the determined duty cycle. Other suitable signals, such as current signals, digital values, etc., may be used according to different examples. In some examples, the controller includes a processor with an integrated PWM circuit, and thus, the controller 1570 can adjust the output duty cycle of the PWM circuit to provide a PWM signal.

[0138] At block 2260 , the power amplifier 1530 outputs a power signal to the transmit coil L7 using the impedance transformation network 1550 based on the determined duty cycle.

[0139] It should be understood that although Figure 22 The method 2200 is described in a specific order, but other orders may be possible. For example, according to some examples, block 2240 and block 2250 can be reversed, or can occur substantially simultaneously.

[0140] Now refer to Figure 23 , Figure 23An example charger device 2300 suitable for use in an example system or method for dynamically controlling near-field wireless power according to the present disclosure is shown. The example computing device 2300 includes a processor 2310 that communicates with a memory 2320 and other components of the computing device 2300 using one or more communication buses 2302. The processor 2310 is configured to execute processor-executable instructions stored in the memory 2320 to perform one or more methods for dynamically controlling near-field wireless power according to different examples, such as those described above with respect to FIG. Figure 21-23 In this example, the computing device also includes one or more user input devices 2350, such as a keyboard, mouse, touch screen, microphone, buttons, etc., to accept user input. The computing device 2300 also includes a display 2340 to provide visual output to the user. In addition, as described above with respect to Figure 11A 、 Figure 11B and 3 As discussed above, the charger device 2300 also includes a wireless field driver 2360 and an EMF sensor 2370.

[0141] The computing device 2300 also includes a communication interface 2330. In some examples, the communication interface 2330 can use one or more communication technologies, such as BT or BLE, or use one or more communication networks, including a local area network ("LAN"); a wide area network ("WAN"), such as the Internet; a metropolitan area network ("MAN"); a point-to-point or peer-to-peer connection, etc., to achieve communication. Communication with other devices can be accomplished using any suitable network protocol. For example, a suitable network protocol can include the Internet Protocol ("IP"), the Transmission Control Protocol ("TCP"), the User Datagram Protocol ("UDP"), or a combination thereof, such as TCP / IP or UDP / IP.

[0142] Although some examples of the methods and systems herein are described in terms of software executed on various machines, these methods and systems may also be implemented as specially configured hardware, such as a field programmable gate array (FPGA) specifically for executing the various methods according to the present disclosure. For example, the examples may be implemented in digital electronic circuits, or in computer hardware, firmware, software, or a combination thereof. In one example, the device may include one or more processors. The processor includes a computer-readable medium, such as a random access memory (RAM) coupled to the processor. The processor executes computer-executable program instructions stored in the memory, such as executing one or more computer programs. Such processors may include microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and state machines. Such processors may further include programmable electronic devices (such as PLCs), programmable interrupt controllers (PICs), programmable logic devices (PLDs), programmable read-only memories (PROMs), electronic programmable read-only memories (EPROMs or EEPROMs), or other similar devices.

[0143] Such a processor may include, or may be in communication with, a medium, such as one or more non-transitory computer-readable media, which may store processor-executable instructions that, when executed by the processor, may cause the processor to perform a method according to the present disclosure as performed or assisted by the processor. Examples of non-transitory computer-readable media may include, but are not limited to, electronic, optical, magnetic, or other storage devices capable of providing processor-executable instructions to a processor, such as a processor in a network server. Other examples of non-transitory computer-readable media include, but are not limited to, floppy disks, CD-ROMs, magnetic disks, memory chips, ROMs, RAMs, ASICs, configured processors, all optical media, all tapes or other magnetic media, or any other medium from which a computer processor can read. The described processors and processes may be in one or more structures and may be distributed through one or more structures. The processor may include code to perform a method (or portion of a method) according to the present disclosure.

[0144] The foregoing description of some examples is presented for the purpose of illustration and description only and is not intended to be exhaustive or to limit the present disclosure to the precise form disclosed. Numerous modifications and adjustments thereof will be apparent to those skilled in the art without departing from the spirit and scope of the present disclosure.

[0145] Reference herein to an example or embodiment means that a particular feature, structure, operation, or other characteristic described in connection with that example may be included in at least one embodiment of the present disclosure. The present disclosure is not limited to the particular examples or embodiments described. The phrases "in one example," "in an example," "in one embodiment," or "in an embodiment," or variations thereof, appearing in different places in the specification do not necessarily refer to the same example or embodiment. Any particular feature, structure, operation, or other characteristic described in this specification for one example or embodiment may be combined with other features, structures, operations, or other characteristics described for any other example or embodiment.

[0146] As used herein, the word "or" is intended to encompass both inclusive and exclusive "or" conditions. In other words, "A" or "B" or "C" includes any or all of the following alternative combinations suitable for a particular purpose: A alone; B alone; C alone; A and B alone; A and C alone; B and C alone; and A, B, and C.

Claims

1. An apparatus for providing wireless power, comprising: a wireless field driver comprising a first antenna coil and a current source electrically coupled to the first antenna coil, the current source comprising a DC / DC converter, a pulse width modulation (PWM) gate controller, and a switching power amplifier; an electromagnetic field (EMF) sensor comprising a second antenna coil and a phase detector, wherein the EMF sensor is configured to generate a sensor signal indicating a strength of a signal from the first antenna coil and a phase signal indicating a phase change; non-transitory computer-readable media; and a processor in communication with the non-transitory computer-readable medium, the processor configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to: causing the current source to output current to the first antenna coil to generate a first EMF; estimating a signal strength of the first EMF based on the sensor signal; determining a change in load impedance based on the phase signal; and Based on the estimated signal strength of the first EMF and the change in the load impedance, the duty cycle of the PWM gate controller and the voltage output by the DC / DC converter are adjusted to adjust the current to the first antenna coil to maintain power characteristics and generate a second EMF at the first antenna coil to charge the wearable device.

2. The device according to claim 1, wherein The first antenna coil and the second antenna coil are concentrically positioned relative to each other, the second antenna coil having a greater width than the first antenna coil.

3. The device according to claim 2, wherein The first antenna coil and the second antenna coil are coplanar with respect to each other.

4. The apparatus according to any one of claims 1 to 3, wherein The EMF sensor is configured to generate a voltage signal or a current signal in response to the EMF, and Also included is a tunable filter electrically coupled to the EMF sensor, the tunable filter configured to selectively filter one or more frequencies from the voltage signal or the current signal.

5. The apparatus according to claim 1, wherein The processor is further configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to determine the presence of foreign matter based on the signal received from the EMF sensor.

6. The apparatus according to claim 1, wherein The processor is further configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to determine one or more harmonic frequencies based on the signal received from the EMF sensor.

7. The apparatus according to claim 1, wherein The EMF sensor also includes a peak detector, and the one or more signals received from the EMF sensor include an amplitude signal output by the peak detector, and wherein the processor is further configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to determine the intensity of the first EMF based on the amplitude signal.

8. The apparatus according to claim 1, wherein The processor is further configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to: determining a field strength difference between a target field strength and an intensity of the first EMF; and The current is adjusted based on the difference in field strength.

9. The apparatus according to claim 1, wherein The EMF sensor further includes a zero-crossing detector, and wherein the processor is further configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to: The intensity of the first EMF is determined based on the phase signal.

10. The apparatus according to claim 1, wherein The processor is further configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to: obtaining data encoded in a signal received from the EMF sensor based on the change in the load impedance; determining a received EMF strength based on data encoded in the signal; as well as The current is adjusted based on the received EMF strength.

11. The apparatus of claim 1 , further comprising a power sensor electrically coupled to the wireless field driver, and wherein The processor is further configured to execute processor-executable instructions stored in the non-transitory computer-readable medium to: changing the switching frequency of the current source; maintaining a constant intensity of the first EMF based on one or more signals received from the EMF sensor; receiving a power signal corresponding to the changed switching frequency from the power sensor, the power signal indicating power output by the switching power amplifier at the changed switching frequency; as well as An efficient switching frequency of the switching power amplifier is established based on the changed switching frequency and the corresponding power output by the switching power amplifier at the changed switching frequency.

12. A method for providing wireless power, comprising: Enable a current source of a wireless field driver of the wireless device to output current to the first antenna coil to generate a first EMF, the current source comprising a DC / DC converter, a pulse width modulation (PWM) gate controller, and a switching power amplifier; receiving one or more signals indicating a sensed intensity of a first EMF and a phase change from an EMF sensor of the wireless device, the EMF sensor comprising a second antenna coil; estimating a strength of the first EMF based on the one or more sensor signals; determining a change in load impedance based on the phase change; as well as The processor adjusts the duty cycle of the PWM gate controller and the voltage output by the DC / DC converter based on the estimated intensity of the first EMF and the phase change to adjust the current, so as to generate a second EMF at the first antenna coil to charge another wearable device.

13. The method according to claim 12, wherein: The first antenna coil and the second antenna coil are concentrically positioned relative to each other, the second antenna coil having a greater width than the first antenna coil.

14. The method according to claim 13, wherein The first antenna coil and the second antenna coil are coplanar with respect to each other.

15. The method according to any one of claims 12 to 14, wherein The EMF sensor is configured to generate a voltage signal or a current signal in response to the EMF, and Also included is filtering one or more frequencies from the voltage signal or the current signal using a tunable filter electrically coupled to the EMF sensor.

16. The method of claim 12, further comprising determining the presence of foreign matter based on a signal received from the EMF sensor.

17. The method of claim 12, further comprising determining one or more harmonic frequencies based on the signal received from the EMF sensor.

18. The method according to claim 12, wherein: The EMF sensor further includes a peak detector, and the one or more signals received from the EMF sensor include an amplitude signal output by the peak detector, and the method further includes determining an intensity of the first EMF based on the amplitude signal.

19. The method according to claim 12, further comprising: determining a field strength difference between a target field strength and an intensity of the first EMF; as well as The current is adjusted based on the field strength difference.

20. The method according to claim 12, wherein The EMF sensor further comprises a zero crossing detector, and the method further comprises: The intensity of the first EMF is determined based on a phase signal indicative of the phase change.

21. The method according to claim 12, further comprising: obtaining data encoded in a signal received from the EMF sensor based on the change in the load impedance; determining a received EMF strength based on data encoded in the signal; as well as The current is adjusted based on the received EMF strength.

22. The method according to claim 12, wherein The wireless device also includes a power sensor electrically coupled to the wireless field driver, and the method further includes: changing the switching frequency of the current source; maintaining a constant intensity of the first EMF based on one or more signals received from the EMF sensor; receiving a power signal corresponding to the changed switching frequency from the power sensor, the power signal indicating power output by the switching power amplifier at the changed switching frequency; and An efficient switching frequency of the switching power amplifier is established based on the changed switching frequency and the corresponding power output by the switching power amplifier at the changed switching frequency.

23. A non-transitory computer-readable medium comprising processor-executable instructions to cause the processor to: Enable a current source of a wireless field driver of the wireless device to output current to the first antenna coil to generate a first EMF, the current source comprising a DC / DC converter, a pulse width modulation (PWM) gate controller, and a switching power amplifier; receiving one or more signals indicative of a sensed intensity of a first EMF and a phase change from an electromagnetic field (EMF) sensor, the EMF sensor comprising a second antenna coil; determining an intensity of the first EMF based on the one or more signals; determining a change in load impedance based on the phase change; as well as The duty cycle of the PWM gate controller and the voltage output by the DC / DC converter are adjusted based on the sensed intensity of the first EMF and the phase change to adjust the current to generate a second EMF to charge another wearable device.

24. The non-transitory computer-readable medium of claim 23, further comprising processor-executable instructions configured to cause the processor to determine the presence of foreign matter based on the signal received from the EMF sensor.

25. The non-transitory computer-readable medium of any one of claims 23 to 24, further comprising processor-executable instructions configured to cause a processor to determine one or more harmonic frequencies based on a signal received from the EMF sensor.

26. The non-transitory computer-readable medium of claim 23, wherein: The EMF sensor further includes a peak detector, and the one or more signals received from the EMF sensor include an amplitude signal output by the peak detector, and further includes processor-executable instructions configured to cause the processor to determine an intensity of the first EMF based on the amplitude signal.

27. The non-transitory computer-readable medium of claim 23, further comprising processor-executable instructions configured to cause the processor to: determining a field strength difference between a target field strength and an intensity of the first EMF; and The current is adjusted based on the field strength difference.

28. The non-transitory computer-readable medium of claim 23, wherein: The EMF sensor further includes a zero-crossing detector and further includes processor-executable instructions configured to cause the processor to: The intensity of the first EMF is determined based on a phase signal indicative of the phase change.

29. The non-transitory computer-readable medium of claim 23, further comprising processor-executable instructions configured to cause the processor to: obtaining data encoded in a signal received from the EMF sensor based on the change in the load impedance; determining a received EMF strength based on data encoded in the signal; as well as The current is adjusted based on the received EMF strength.

30. The non-transitory computer-readable medium of claim 23, wherein: The wireless device also includes a power sensor electrically coupled to the wireless field driver, and further includes processor-executable instructions configured to cause the processor to: changing the switching frequency of the current source; maintaining a constant intensity of the first EMF based on one or more signals received from the EMF sensor; receiving a power signal corresponding to the changed switching frequency from the power sensor, the power signal indicating power output by the switching power amplifier at the changed switching frequency; as well as An efficient switching frequency of the switching power amplifier is established based on the changed switching frequency and the corresponding power output by the switching power amplifier at the changed switching frequency.

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