WIRELESS POWER BASE UNIT AND A SYSTEM AND METHOD FOR WIRELESSLY CHARGING DISTANCE SEPARATED ELECTRONIC DEVICES

Abstract

Base units, systems and methods for wireless energy transfer are described. A wireless energy transfer system according to some examples includes a transmitter of wireless energy located within a communication device, such as a mobile phone, or attached to the communication device and a distance separated receiver located within an electronic wearable device other than the communication device, wherein the receiver is configured to receive wireless energy from the transmitter and convert the wireless energy into electrical power, which may be used to power the electronic wearable device.

Description

TECHNICAL FIELD

The present disclosure relates to systems and methods for providing power wirelessly to one or more electronic devices.

BACKGROUND

The number and types of commercially available electronic wearable devices continues to expand. Forecasters are predicting that the electronic wearable devices market will more than quadruple in the next ten years. Some hurdles to realizing this growth remain. Two major hurdles are the cosmetics/aesthetics of existing electronic wearable devices and their limited battery life. Consumers typically desire electronic wearable devices to be small, less noticeable, and require less frequent charging. Typically, consumers are unwilling to compromise functionality to obtain the desired smaller form factor and extended battery life. The desire for a small form factor yet a longer battery life are goals which are in direct conflict with one another and which conventional devices are struggling to address. Further solutions in this area may thus be desirable.

SUMMARY

Examples of base units, systems and methods for wireless energy transfer are described. A base unit according to some examples herein includes a transmitter configured for wireless power delivery, the transmitter including a coil comprising a magnetic core, a battery coupled to the transmitter, a controller coupled to the battery and the transmitter and configured to cause the transmitter to selectively transmit power from the battery to an electronic device separated from the base unit, and a housing enclosing the transmitter, the battery, and the controller, the housing configured to be mechanically coupled to a mobile phone.

A system according to some examples includes a base unit including a transmitter configured for wireless power delivery and a battery coupled to the transmitter, wherein the transmitter includes a transmitting coil having a magnetic core, and an electronic device separated from the base unit, the electronic device including a receiver inductively coupled to the transmitter to receive power from the base unit while the electronic device remains within a threshold distance from the base unit. The receiver of the electronic device includes a receiving coil having a magnetic core, wherein a dimension of the transmitting coil is at least twice a dimension of the receiving coil.

A method according to some examples includes moving a mobile phone to a position proximate an electronic device, wherein a base unit is attached to the mobile phone and wherein the electronic device is not attached to the mobile phone, wherein the base unit includes a transmitting coil for wirelessly transmitting power to a receiving coil on the electronic device, and wherein the position proximate an electronic device is defined by a distance between the base unit and the electronic device less than a charging range of the base unit. The method further includes detecting the electronic device with the base unit or the mobile phone, and wirelessly transmitting power signals to the electronic device while the electronic device remains within the charging range of the base unit or until a charge state signal of the electronic device corresponds to a fully charged state of the electronic device.

A wireless energy transfer system according to some examples includes a transmitter of wireless power located within a mobile phone and a distance separated receiver located within an electronic wearable device other than the mobile phone, wherein the receiver is configured to receive wireless power from the transmitter.

A wireless energy transfer system according to the examples herein may include a base unit which includes a transmitter comprising a first coil and a first magnetic core. The wireless energy transfer system may further include a distance separated electronic device which includes a receiver comprising a second coil and second magnetic core, wherein a dimension of the first coil or first core is two times or greater a same dimension of the second coil or second core. The wireless energy transfer system may be configured to operate at a frequency within the range of 50 kHz or 500 kHz using an amount of guided flux, and the transmitter and the receiver of the wireless energy transfer system may be configured to operate in weak resonance. In some examples, the Q value of the wireless energy transfer system is less than 100. In some examples, the wireless energy transfer system may be configured to operate at a frequency within the range of 75 kHz to 200 kHz. In some examples, the guided flux may be a partially guided flux. In some examples, the first magnetic core, the second magnetic core, or both may be ferrite cores. In some examples, the first coil, the second coil, or both may include windings of multi-strand wire.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects and attendant advantages of the present invention will become apparent from the following detailed description of various embodiments, including the best mode presently contemplated of practicing the invention, when taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a block diagram of a system according to examples of the present disclosure;

FIG. 2 illustrates examples of electronic devices attached to eyewear in accordance with the present disclosure;

FIG. 3 illustrates an example of a receiving coil for an electronic device and a transmitting coil for a base unit in accordance with the present disclosure;

FIG. 4 illustrates a block diagram of a mobile base unit implemented in a mobile phone case form factor according to examples of the present disclosure;

FIGS. 5A and 5B illustrate isometric and exploded isometric views of a base unit implemented as a mobile phone case according to examples of the present disclosure;

FIG. 6 illustrates a flow chart of a process according to some examples herein;

FIG. 7 illustrates a flow chart of a process according to further examples herein;

FIG. 8 illustrates a typical use scenario of a base unit incorporated into or attached to a mobile phone;

FIG. 9A-E illustrate views of a base unit according to some examples of the present disclosure;

FIG. 10A-C illustrate views of a base unit implemented in the form of a case for a communication device, such as a tablet;

FIG. 11A-D illustrate views of a base unit implemented as a partial case for a communication device;

FIGS. 12A and 12B illustrate views of a base unit implemented as a partial case with movable cover configured for coupling to a communication device;

FIG. 13 illustrates an exploded isometric view of a base unit according to further examples of the present disclosure;

FIG. 14A-C illustrate views of the base unit in FIG. 13;

FIG. 15A-C illustrate arrangements of transmitting coils of base units according to examples of the present disclosure;

FIG. 16A-C illustrate arrangements of transmitting coils of base units according to further examples of the present disclosure;

FIG. 17 illustrates a base unit in the form of a puck in accordance with further examples herein;

FIG. 18 illustrates an example transmitter and receiver configuration in accordance with the present disclosure;

FIG. 19A illustrates simulation results of wireless power transfer systems according to some examples of the present disclosure;

FIG. 20 illustrates simulation results of wireless power transfer systems according to further examples of the present disclosure;

FIG. 21 illustrates a comparison between wireless power transfer systems according to some examples of the present disclosure and Q standard systems; and

FIG. 22 illustrates magnetic field lines of inductively coupled transmitting and receiving coils in accordance with some examples herein.

DETAILED DESCRIPTION

Systems, methods and apparatuses for wirelessly powering electronic devices are described. Systems and methods in accordance with the examples herein may provide wireless power at greater distance separation between the power transmitting and receiving coils than commercially available systems. Additional advantages may be improved thermal stability and orientation freedom, as will be described further below.

According to some examples herein, a wireless power transfer system, and more specifically a weakly resonant system with relatively broad resonance amplification with moderate frequency dependence, is described. In accordance with some examples herein, dependence on the relative sizes of the inductive coils and orientation between the coils may be reduced as compared to such dependence on coil sizes and orientation typically found in commercially available systems with strong resonant coupling at Q factors exceeding 100. In some examples according to the present disclosure, wireless power transfer systems may operate at Q value less than 100. Unlike commercially available systems, which typically use air core coils, according to some examples herein, the shape of the magnetic field between the coils may be augmented, for example by using a medium with high permeability such as ferrite. According to some examples, guided flux or partially guided flux may be used to improve the performance of the system in a given orientation. An appropriate frequency, for example a body safe frequency, is used for power broadcast. The broadcast frequency may be tuned to reduce losses that may result from shielding effects.

FIG. 1 shows a block diagram of a system for wirelessly powering one or more electronic devices according to some examples of the present disclosure. The system 10 includes a base unit 100 and one or more electronic devices 200. The base unit 100 is configured to wirelessly provide power to one or more of the electronic devices 200, which may be separated from the base unit by a distance. The base unit 100 is configured to provide power wirelessly to an electronic device 200 while the electronic device remains within a threshold distance (e.g., a charging range or charging zone 106) of the base unit 100. The base unit 100 may be configured to selectively transmit power wirelessly to any number of electronic devices (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 although a greater number than 10 devices may be charged in some examples) detected to be within a proximity (e.g., within the charging range) of the base unit 100. Although the electronic device 200 may typically be charged (e.g., coupled to the base unit for charging) while being distance-separated from the base unit 100, it is envisioned and within the scope of this disclosure that the base unit 100 may operate to provide power wirelessly to an electronic device 200 when the electronic device 200 is adjacent to or in contact with the base unit 100.

The base unit 100 includes a transmitter 110, a battery 120, and a controller 130. The transmitter 110 includes at least one transmitting coil 112 (interchangeably referred to as Tx coil). The transmitting coil 112 may include a magnetic core with conductive windings. The windings may include copper wire (also referred to as copper windings). In some examples, the copper wire may be monolithic copper wire (e.g., single-strand wire).

In some examples, the copper wire may be multi-strand copper wire (e.g., Litz wire), which may reduce resistivity due to skin effect in some examples, which may allow for higher transmit power because resistive losses may be lower. In some examples, the magnetic core may be a ferrite core (interchangeably referred to as ferrite rod). The ferrite core may comprise a medium permeability ferrite, for example 78 material supplied by Fair-Rite Corporation. In some examples, the ferrite core may comprise a high permeability material, such as Vitroperm 500F supplied by Vacuumschmelze in Germany. Ferrite cores comprising other ferrite materials may be used. In some examples, the ferrite may have a medium permeability of micro-i (μ) of about 2300. In some examples, the ferrite may have permeability of micro-i (μ) ranging from about 200 to about 5000. In some examples, different magnetic material may be used for the magnetic core. Generally, transmitting coils described herein may utilize magnetic cores which may in some examples shape the field provided by the transmitting coil, as the field lines preferentially go through the magnetic core, in this manner, partially guided flux may be used where a portion of the flux is guided by the magnetic core.

The transmitting coil 112 is configured to inductively couple to a receiving coil 210 in the electronic device 200. In some examples, the transmitter 110 may be additionally configured as a receiver and may thus be interchangeably referred to as transmitter/receiver. For example, the transmitting coil of the transmitter/receiver may additionally be configured as a receiving coil. In some examples, the transmitter/receiver may additionally include a receiving coil. In yet further examples, the base unit may include a separate receiver 140 comprising a receiving coil. The transmitter/receiver or separate receiver of the base unit may be configured to wirelessly receive power (102) and/or data (104) as will be further described below.

In some examples, the transmitter 110 may include a single transmitting coil 112. The transmitting coil 112 may be placed in an optimal location and/or orientation to provide an optimum charging zone 106. In some examples, the transmitting coil may be placed in a location within the base unit selected to provide a large number of charging opportunities during a typical use of the device. For example, the transmitting coil 112 may be placed near a side of the base unit which most frequently comes in proximity to an electronic device (e.g., a top side of a base unit implemented as a mobile phone case as illustrated in the example in FIG. 6).

In some examples, the transmitter 110 includes a plurality of transmitting coils 112. The transmitting coils 112 may be arranged in virtually any pattern. For example, the base unit may include a pair of coils which are angled to one another. In some examples, the coils may be arranged at angles smaller than 90 degrees, for example ranging between 15-75 degrees. In some examples, the coils may be arranged at 45 degrees relative to one another. Other combinations and arrangements may be used, examples of some of which will be further described below.

In some examples, the transmitting coils may be arranged to provide a nearly omnidirectional charging zone 106 (also referred to as charging sphere or hotspot). The charging zone 106 of the base unit may be defined by a three dimensional space around the base unit which extends a threshold distance from the base unit in all three directions (e.g., the x, y, and z directions). Although a three dimensions (3D) space corresponding to a charging range of the base unit may be referred to herein as a sphere, it will be understood that the three dimensions (3D) space corresponding to a charging range need not be strictly spherical in shape. In some examples, the charging sphere may be an ellipsoid or a different shape.

Efficiency of wireless power transfer within the charging zone 106 may be variable, for example, depending on a particular combination of transmitting and receiving coils and/or a particular arrangement of the coils or relative arrangements of the coils in the base unit and electronic device(s). The one or more transmitting coils 112 may be arranged within a housing of the base unit in a manner which improves the omni-directionality of the charging zone 106 and/or improves the efficiency of power transmission within the zone 106. In some examples, one or more transmitting coils 112 may be arranged within the housing in a manner which increases the opportunities for charging during typical use of the base unit. For example, the transmitting coil(s) may extend, at least partially, along one or more sides of the base unit which are most brought near an electronic device (e.g., the top or sides of a mobile phone case base unit which may frequently be moved in proximity with a wearable electronic device such as eyewear camera or a digital wrist watch). In some examples, the base unit may be placed on a surface (e.g., a table or desk) during typical use and electronic devices may be placed around the base unit. In such examples, the transmitting coil(s) may be arranged along a perimeter of the base unit housing.

In some examples, the base unit may be attached to a mobile phone via an attachment mechanism such as adhesive attachment, an elastic attachment, a spring clamp, suction cup(s), mechanical pressure, or others. In some examples, the base unit may be enclosed or embedded in an enclosure (also referred to as housing), which may have a generally planar shape (e.g., a rectangular plate). An attachment mechanism may be coupled to the housing such that the base unit may be removably attached to a mobile phone, a table, or other communication device. In an example, the attachment mechanism may be a biasing member, such as a clip, which is configured to bias the mobile phone towards the base unit in the form of, by way of example only, a rectangular plate. For example, a clip may be provided proximate a side of the base unit and the base unit may be attached to (e.g., clipped to) the mobile phone via the clip in a manner similar to attaching paper or a notebook/notepad to a clip board. In some examples, the base unit may be adhesively or elastically attached to the communication device and/or to a case of the communication device.

In further examples, the base unit may be separate from the communication device. In yet further examples, the base unit may be incorporated into (e.g., integrated into) the communication device. For example, the transmitter 110 may be integrated with other components of a typical mobile phone. The controller 130 may be a separate IC in the mobile phone or its functionality may be incorporated into the processor and/or other circuitry of the mobile phone. Typical mobile phones include a rechargeable battery which may also function as the battery 120 of the base unit. In this manner, a mobile phone may be configured to provide power wirelessly to electronic devices, such as a separated electronic wearable devices.

As previously noted, the base unit 100 may include a battery 120. The battery 120 may be a rechargeable battery, such as a Nickel-Metal Hydride (NiMH), a Lithium ion (Li-ion), or a Lithium ion polymer (Li-ion polymer) battery. The battery 120 may be coupled to other components to receive power. For example, the battery 120 may be coupled to an energy generator 150. The energy generator 150 may include an energy harvesting device which may provide harvested energy to the battery for storage and use in charging the electronic device(s). Energy harvesting devices may include, but not be limited to, kinetic-energy harvesting devices, solar cells, thermoelectric generators, or radio-frequency harvesting devices. In some examples, the battery 120 may be coupled to an input/output connector 180 such as a universal serial bus (USB) port. It will be understood that the term USB port herein includes any type of USB interface currently known or later developed, for example mini and micro USB type interfaces. Other types of connectors, currently known or later developed, may additionally or alternatively be used. The I/O connector 180 (e.g., USB port) may be used to connect the base unit 100 to an external device, for example an external power source or a computing device (e.g., a personal computer, laptop, tablet, or a mobile phone).

The transmitter 110 is operatively coupled to the battery 120 to selectively receive power from the battery and wirelessly transmit the power to the electronic device 200. As described herein, in some examples, the transmitter may combine the functionality of transmitter and receiver. In such examples, the transmitter may also be configured to wirelessly receive power from an external power source. It will be understood that during transmission, power may be wirelessly broadcast by the transmitter and may be received by any receiving devices within proximity (e.g., within the broadcast distance of the transmitter).

The transmitter 110 may be weakly-coupled to a receiver in the electronic device 200 in some examples. There may not be a tight coupling between the transmitter 110 and the receiver in the electronic device 200. Highly resonant coupling may be considered tight coupling. The weak (or loose) coupling may allow for power transmission over a distance (e.g. from a base unit in or on a mobile phone to a wearable device on eyewear or from a base unit placed on a surface to a wearable device placed on the surface in a neighborhood of, but not on, the base unit). So, for example, the transmitter 110 may be distance separated from the receiver. The distance may be greater than 1 mm in some examples, greater than 10 mm in some examples, greater than 100 mm in some examples, and greater than 1000 mm in some examples. Other distances may be used in other examples, and power may be transferred over these distances.

The transmitter 110 and the receiver in the electronic device 200 may include impedance matching circuits each having an inductance, capacitance, and resistance. The impedance matching circuits may function to adjust impedance of the transmitter 110 to better match impedance of a receiver under normal expected loads, although in examples described herein the transmitter and receiver may have transmit and receive coils, respectively, with different sizes and/or other characteristics such that the impedance of the receiver and transmitter may not be matched by the impedance matching circuits, but the impedance matching circuits may reduce a difference in impedance of the transmitter and receiver. The transmitter 110 may generally provide a wireless power signal which may be provided at a body-safe frequency, e.g. less than 500 kHz in some examples, less than 300 kHz in some examples, less than 200 kHz in some examples, 125 kHz in some examples, less than 100 kHz in some examples, although other frequencies may be used.

Transmission/broadcasting of power may be selective in that a controller controls when power is being broadcast. The base unit may include a controller 130 coupled to the battery 120 and transmitter 110. The controller 130 may be configured to cause the transmitter 110 to selectively transmit power, as will be further described. A charger circuit may be connected to the battery 120 to protect the battery from overcharging. The charger circuit may monitor a level of charge in the battery 120 and turn off charging when it detects that the battery 120 is fully charged. The functionality of the charger circuit may, in some examples, be incorporated within the controller 130 or it may be a separated circuit (e.g., separate IC chip).

In some examples, the base unit may include a memory 160. The memory 160 may be coupled to the transmitter 110 and/or any additional transmitters and/or receivers (e.g., receiver 140) for storage of data transmitted to and from the base unit 100. For example, the base unit 100 may be configured to communicate data wirelessly to and from the electronic device 200, e.g., receive images acquired with an electronic device in the form of a wearable camera, or transmit configuration data to the electronic device. The base unit may include one or more sensors 170, which may be operatively coupled to the controller. A sensor 170 may detect a status of the base unit such that the transmitter may provide power selectively and/or adjustably under control from controller 130.

The electronic device 200 may be configured to provide virtually any functionality, for example an electronic device configured as a wearable camera, an electronic watch, electronic band, and other such smart devices. In addition to circuitry adapted to perform the specific function of the electronic device, the electronic device 200 may further include circuitry associated with wireless charging. The electronic device 200 may include at least one receiving coil 212, which may be coupled to a rechargeable power cell onboard the electronic device 200. Frequent charging in a manner that is non-invasive or minimally invasive to the user during typical use of the electronic device may be achieved via wireless coupling between the receiving and transmitting coils in accordance with the examples herein.

In some examples, the electronic device may be a wearable electronic device, which may interchangeably be referred to herein as electronic wearable devices. The electronic device may have a sufficiently small form factor to make it easily portable by a user. The electronic device 200 may be attachable to clothing or an accessory worn by the user, for example eyewear. For example, the electronic device 200 may be attached to eyewear using a guide 6 (e.g., track) incorporated in the eyewear, e.g., as illustrated in FIG. 2 (only a portion of eyewear, namely the temple, is illustrated so as not to clutter the drawing). FIG. 2 shows examples of electronic devices 200 which may be configured to receive power wirelessly in accordance with the present disclosure. In some examples, the electronic device 200 may be a miniaturized camera system which may, in some examples, be attached to eyewear. In other examples, the electronic device may be any other type of an electronic system attached to eyewear, such as an image display system, an air quality sensor, a UV/HEV sensor, a pedometer, a night light, a blue tooth enabled communication device such as blue tooth headset, a hearing aid or an audio system. In some examples, the electronic device may be worn elsewhere on the body, for example around the wrist (e.g., an electronic watch or a biometric device, such as a pedometer). The electronic device 200 may be another type of electronic device other than the specific examples illustrated. The electronic device 200 may be virtually any miniaturized electronic device, for example and without limitation a camera, image capture device, IR camera, still camera, video camera, image sensor, repeater, resonator, sensor, sound amplifier, directional microphone, eyewear supporting an electronic component, spectrometer, directional microphone, microphone, camera system, infrared vision system, night vision aid, night light, illumination system, sensor, pedometer, wireless cell phone, mobile phone, wireless communication system, projector, laser, holographic device, holographic system, display, radio, GPS, data storage, memory storage, power source, speaker, fall detector, alertness monitor, geo-location, pulse detection, gaming, eye tracking, pupil monitoring, alarm, CO sensor, CO detector, CO2 sensor, CO2 detector, air particulate sensor, air particulate meter, UV sensor, UV meter, IR sensor IR meter, thermal sensor, thermal meter, poor air sensor, poor air monitor, bad breath sensor, bad breath monitor, alcohol sensor, alcohol monitor, motion sensor, motion monitor, thermometer, smoke sensor, smoke detector, pill reminder, audio playback device, audio recorder, speaker, acoustic amplification device, acoustic canceling device, hearing aid, assisted hearing assisted device, informational earbuds, smart earbuds, smart ear-wearables, video playback device, video recorder device, image sensor, fall detector, alertness sensor, alertness monitor, information alert monitor, health sensor, health monitor, fitness sensor, fitness monitor, physiology sensor, physiology monitor, mood sensor, mood monitor, stress monitor, pedometer, motion detector, geo-location, pulse detection, wireless communication device, gaming device, eyewear comprising an electronic component, augmented reality system, virtual reality system, eye tracking device, pupil sensor, pupil monitor, automated reminder, light, alarm, cell phone device, phone, mobile communication device, poor air quality alert device, sleep detector, doziness detector, alcohol detector, thermometer, refractive error measurement device, wave front measurement device, aberrometer, GPS system, smoke detector, pill reminder, speaker, kinetic energy source, microphone, projector, virtual keyboard, face recognition device, voice recognition device, sound recognition system, radioactive detector, radiation detector, radon detector, moisture detector, humidity detector, atmospheric pressure indicator, loudness indicator, noise indicator, acoustic sensor, range finder, laser system, topography sensor, motor, micro motor, nano motor, switch, battery, dynamo, thermal power source, fuel cell, solar cell, kinetic energy source, thermo electric power source, smart band, smart watch, smart earring, smart necklace, smart clothing, smart belt, smart ring, smart bra, smart shoes, smart footwear, smart gloves, smart hat, smart headwear, smart eyewear, and other such smart devices. In some examples, the electronic device 200 may be a smart device. In some examples, the electronic device 200 may be a micro wearable device or an implanted device.

The electronic device 200 may include a receiver (e.g., Rx coil 212) configured to inductively couple to the transmitter (e.g. Tx coil 112) of the base unit 100. The receiver may be configured to automatically receive power from the base unit when the electronic device and thus the receiver is within proximity of the base unit (e.g., when the electronic device is a predetermined distance, or within a charging range, from the base unit). The electronic device 200 may store excess power in a power cell onboard the electronic device. The power cell onboard the electronic device may be significantly smaller than the battery of the base unit. Frequent recharging of the power cell may be effected by virtue of the electronic device frequently coming within proximity of the base unit during normal use. For example, in the case of a wearable electronic device coupled to eyewear and a base unit in the form of a cell phone case, during normal use, the cell phone may be frequently brought to proximity of the user's head to conduct phone calls during which times recharging of the power cell onboard the wearable electronic device may be achieved. In some examples, in which the wearable electronic device comprises an electronic watch or biometric sensor coupled to a wrist band or a arm band, the wearable electronic device may be frequently recharged by virtue of the user reaching for their cellphone and the base unit in the form of a cell phone case coming within proximity to the wearable electronic device. In some examples, the electronic device may include an energy harvesting system.

In some examples, the electronic device 200 may not include a battery and may instead be directly powered by wireless power received from the base unit 100. In some examples, the electronic device 200 may include a capacitor (e.g., a supercapacitor or an ultracapacitor) operatively coupled to the Rx coil 212.

Typically in existing systems which apply wireless power transfer, transmitting and receiving coils may have the same or substantially the same coil ratios. However, given the smaller form factor of miniaturized electronic devices according to the present disclosure, such implementation may not be practical. In some examples herein, the receiving coil may be significantly smaller than the transmitting coils, e.g., as illustrated in FIG. 3. In some examples, the Tx coil 112 may have a dimension (e.g., a length of the wire forming the windings 116, a diameter of the wire forming the windings 116, a diameter of the coil 112, a number of windings 116, a length of the core 117, a diameter of the core 117, a surface area of the core 117) which is greater, for example twice or more, than a respective dimension of the Rx coil 212 (e.g., a length of the wire forming the windings 216, a diameter of the coil 212, a number of windings 216, a length of the core 217, a surface area of the core 217). In some examples, a dimension of the Tx coil 112 may be two times or greater, five times or greater, 10 times or greater, 20 times or greater, or 50 times or greater than a respective dimension of the Rx coil 212. In some examples, a dimension of the Tx coil 112 may be up to 100 times a respective dimension of the Rx coil 212. For example, the receiving coil 212 (Rx coil) may comprise conductive wire having wire diameter of about 0.2 mm. The wire may be a single strand wire. The Rx coil in this example may have a diameter of about 2.4 mm and a length of about 13 mm. The Rx coil may include a ferrite rod having a diameter of about 1.5 mm and a length of about 15 mm. The number of windings in the Rx coil may be, by way of example only, approximately 130 windings. The transmitting coil 112 (Tx coil) may comprise a conductive wire having a wire diameter of about 1.7 mm. The wire may be a multi-strand wire. The Tx coil in this example may have a diameter of about 14.5 mm and a length of about 67 mm. The Tx coil may include a ferrite rod having a diameter of about 8 mm and a length of about 68 mm. Approximately 74 windings may be used for the Tx coil. Other combinations may be used for the Tx and Rx coils in other examples, e.g., to optimize power transfer efficiency even at distances in excess of approximately 30 cm or more. In some examples, the transfer distance may exceed 12 inches. In some examples herein, the Tx and Rx coils may not be impedance matched, as may be typical in conventional wireless power transfer systems. Thus, in some examples, the Tx and Rx coils of the base unit and electronic device, respectively, may be referred to as being loosely-coupled. According to some examples, the base unit is configured for low Q factor wireless power transfer. For example, the base unit may be configured for wireless power transfer at Q factors less than 500 in some examples, less than 250 in some examples, less than 100 in some examples, less than 80 in some examples, less than 60 in some examples, and other Q factors may be used. While impedance matching is not required, examples in which the coils are at least partially impedance matched are also envisioned and within the scope of this disclosure. While the Tx and Rx coils in wireless powers transfer systems described herein may be typically loosely coupled, the present disclosure does not exclude examples in which the Tx and Rx coils are impedance matched.

The receiving coil (e.g., Rx coil 212) may include conductive windings, for example copper windings. Conductive materials other than copper may be used. In some examples, the windings may include monolithic (e.g., single-strand) or multi-strand wire. In some examples, the core may be a magnetic core which includes a magnetic material such as ferrite. The core may be shaped in the form of a rod. The Rx coil may have a dimension that is smaller than a dimension of the Tx coil, for example a diameter, a length, a surface area, and/or a mass of the core (e.g., rod) may be smaller than a diameter, a length, a surface area, and/or a mass of the core (e.g., rod) of the Tx coil. In some examples, the magnetic core (e.g., ferrite rod) of the Tx coil may have a surface area that is two greater or more than a surface area of the magnetic core (e.g., ferrite rod) of the Rx coil. In some examples, the Tx coil may include a larger number of windings and/or a greater length of wire in the windings when unwound than the number or length of wire of the windings of the Rx coil. In some examples, the length of unwound wire of the Tx coil may be at least two times the length of unwound wire of the Rx coil.

In some examples, an Rx coil 212 may have a length from about 10 mm to about 90 mm and a radius from about 1 mm to about 15 mm. In one example, the performance of an Rx coil 212 having a ferrite rod 20 mm in length and 2.5 mm in diameter with 150 conductive windings wound thereupon was simulated with a Tx coil 112 configured to broadcast power at frequency of about 125 KHz. The Tx coil 112 included a ferrite rod having a length of approximately 67.5 mm and a diameter of approximately 12 mm. The performance of the coils was simulated in an aligned orientation in which the coils were coaxial and in a parallel orientation in which the axes of the coils were parallel to one another, and example results of simulations performed are shown in FIGS. 21 and 22. Up to 20% transmission efficiency was obtained in the aligned orientation at distances of up to 200 mm between the coils. Some improvement was observed in the performance when the coils were arranged in a parallel orientation, in which the Rx coil continued to receive transmitted power until a distance of about 300 mm. Examples of a wireless energy transfer system according to the present disclosure were compared with efficiency achievable by a system configured in accordance with the Qi 1.0 standard. The size of the Tx coil in one simulated system was 52 mm×52 mm×5.6 mm and a size of one Rx coil simulated was 48.2 mm×32.2 mm×1.1 mm, and load impedance was 1 KOhm. Simulations were performed in an aligned configuration with several Rx coil sizes, and example results of simulations performed are shown in FIG. 23.

Referring now also to FIGS. 5A and 5B, a base unit 300 incorporated in a mobile phone case form factor will be described. The base unit 300 may include some or all of the components of base unit 100 described above with reference to FIG. 1. For example, the base unit 300 may include a transmitting coil 312 (also referred to as Tx coil). The transmitting coil 312 is coupled to an electronics package 305, which includes circuitry configured to perform the functions of a base unit in accordance with the present disclosure, including selectively and/or adjustably providing wireless power to one or more electronic devices. In some examples, the electronic device may be an electronic device which is separated from the base unit (not shown in FIGS. 5A-5B). In some examples, the electronic device may be the mobile phone 20, to which the base unit 300 in the form of a case is attached.

The base unit 300 may provide a mobile wireless hotspot (e.g., charging sphere 106) for wirelessly charging electronic devices that are placed or come into proximity of the base unit (e.g., within the charging sphere). As will be appreciated, the base unit 300 when implemented in the form of a mobile phone case may be attached to a mobile phone and carried by the user, thus making the hotspot of wireless power mobile and available to electronic devices wherever the user goes. In examples, the base unit may be integrated with the mobile phone. The hotspot of wireless power by virtue of being connected to the user's mobile phone, which the user often or always carries with him or her, thus advantageously travels with the user. As will be further appreciated, opportunities for recharging the power cell on an electronic device worn by the user are frequent during the normal use of the mobile phone, which by virtue of being use may frequently be brought into the vicinity of wearable devices (e.g., eyewear devices when the user is making phone calls, wrist worn devices when the user is browsing or using other function of the mobile phone).

The Tx coil 312 and electronics (e.g., electronics package 305) may be enclosed in a housing 315. The housing 315 may have a portable form factor. In this example, the housing is implemented in the form of an attachment member configured to be attached to a communication device in this case a mobile phone (e.g., a mobile phone, a cellular phone, a smart phone, a two-way radio, and the like). In some examples, the communication device may be a tablet. In the context of this disclosure, a mobile phone is meant to include communication devices such as two way radios and walkie-talkies. For example, the housing 315 may be implemented in the form of a tablet case or cover (e.g., as illustrated in FIGS. 10A-C) or a mobile phone case or cover, e.g., as in the present example. In such examples, the base unit incorporated in the housing may power an electronic device other than the communication device. The housing 315 may include features for mechanically engaging the communication device (e.g., mobile phone 20). In further examples, the housing of the base unit may be implemented as an attachment member adapted to be attached to an accessory, such as a handbag, a belt, or others. Other form factors may be used, for example as described below with reference to FIG. 17.

In the examples in FIGS. 4 and 5, the base unit 300 includes a transmitting coil 312. The transmitting coil 312 includes a magnetic core 317 with conductive windings 316. The core 317 may be made of a ferromagnetic material (e.g., ferrite), a magnetic metal, or alloys or combinations thereof, collectively referred to herein as magnetic material. For example, a magnetic material such as ferrite and various alloys of iron and nickel may be used. The coil 312 includes conductive windings 316 provided around the core 317. It will be understood in the context of this disclosure that the windings 316 may be, but need not be, provided directly on the core 317. In other words, the windings 316 may be spaced from the core material which may be placed within a space defined by the windings 316, as will be described with reference to FIGS. 15-16. In some examples, improved performance may be achieved by the windings being wound directly onto the core as in the present example.

The core 317 may be shaped as an elongate member and may have virtually any cross section, e.g., rectangular or circular cross section. An elongate core may interchangeably be referred to as a rod 314, e.g., a cylindrical or rectangular rod. The term rod may be used to refer to an elongate core in accordance with the present application, regardless of the particular cross sectional shape of the core. The core may include a single rod or any number of discrete rods (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10 or any other number greater than 10) arranged in patterns as will be described. In the examples in FIGS. 4 and 5, without limitation, the transmitting coil comprises a single cylindrical rod positioned at least partially along a first side (e.g., top side 321) of the housing 315. In other examples, one or more coils may alternatively or additionally be positioned along other sides, e.g., a bottom side 323, the left side 325 and/or right sides 327 of the housing 315.

The electronics package 305 (interchangeably referred to as electronics or circuitry) may be embedded in the housing 315 or provided behind a cover 307. In some examples, the cover 307 may be removable. In some examples, it may be advantageous to replace the battery 320. In such examples, the battery 320 may be a separable component from the remaining circuitry. The battery 320 may be accessed by removing the cover 307. In some examples, the electronics package 305 may include a battery for storing energy from an external power source. In some examples, the base unit 300 may alternatively or additionally receive power from the mobile phone when powering the distance separated electronic device. In some examples, the base unit may not require a battery, and even smaller form factors may thus be achieved.

The base unit may be provided with one or more I/O devices 380. I/O devices may be used to receive and/or transmit power and/or data via a wired connection between the base unit and another device. For example, the base unit may include an I/O device 380 in the form of a USB connector. The I/O device 380 (e.g., USB connector) may include a first connection side 382 (e.g., a female port) for coupling the base unit to external devices (e.g., a power source such as the power grid and/or another electronic device). The I/O device 380 may include a second connection side 384 (e.g., a male connector) for coupling the base unit to the mobile phone, e.g., via a USB port of the mobile phone. One or more of the signal lines 385 of the I/O device may be coupled to power, ground, and/or data lines in the base unit circuitry. For example, if a USB connector with 5 lines is used, 2 lines may be used for data, 2 lines may be used for power, and 1 line may be coupled to ground or used for redundancy. The signal lines 385 of the first and second connection sides may be coupled to the base unit circuitry via a connector circuit 386 (e.g., USB chip). It will be understood that any other type of connectors may be used, for example, and without limitation, an APPLE Lightning connector.

The base unit 300 may include a controller 330. The controller may include functionality for controlling operations of the base unit, for example controlling detection of electronic devices within proximity, selective transmission of wireless power upon detection of an electronic device, determination of status of the base unit, and selection of transmission mode depending on the status of the base unit. These functions may be implemented in computer readable media or hardwired into an ASICs or other processing hardware. The controller may interchangeably be referred to as base unit processor.

The base unit may include one or more memory devices 360. The base unit may include volatile memory 362 (e.g., RAM) and non-volatile memory 364 (e.g., EEPROM, flash or other persistent electronic storage). The base unit may be configured to receive data (e.g. user data, configuration data) through wired or wireless connection with external electronic devices and may store the data on board the base unit (e.g., in one or more of the memory devices 360). The base unit may be configured to transmit data stored onboard the base unit to external electronic devices as may be desired. In addition to user data, the memory devices may store executable instructions which, when executed by a processor (e.g., processor 360), cause the base unit to perform functions described herein.

The base unit 300 may include a charger circuit 332, which may be configured to protect the battery 320 from overcharging. The charger circuit may be a separate chip or may be integrated within the controller 330. The base unit may include a separate transmitter/receiver circuitry 340 in addition to the Tx coil 312 used for wireless power transmission. The transmitter/receiver circuitry 340 may include a receiving/transmitting coil 342, e.g., an RF coil. The transmitter/receiver circuitry 340 may further include driver circuitry 344 for transmission (e.g., RF driver circuit) and sense circuitry 346 for reception of signals (e.g., RF sensing circuit). The base unit 300 may include additional circuitry for wireless communication (e.g., communication circuit 388). The communication circuit 388 may include circuitry configured for Bluetooth or WiFi communication. In some examples, the base unit 300 may include one or more sensor 370 and/or one or more energy generators 350 as described herein. Additional circuitry providing additional functionality may be included. For example, the base unit 300 may include an image processor for processing and/or enhancement of images received from a wearable camera (e.g., eyewear camera). The image processing functionality may be provided in a separate IC (e.g., a DaVinci chip set) or it may be incorporated in a processor which implements the functions of controller 300.

In some examples, the housing may be configured to be mechanically coupled to a communication device, such as a mobile phone. In the examples in FIGS. 4 and 5, the housing 315 is configured to provide the functionality of a mobile phone case. The housing may have a shape corresponding to a shape of a communication device (e.g., a mobile phone). For example, the housing may be generally rectangular in shape and may be sized to receive, at least partially, or enclose, at least partially, the communication device. In some examples, the housing may be configured to cover only one side of the communication device. In some examples, the housing may cover at least partially two or more sides of the communication device. In the examples in FIGS. 4 and 5, the housing 315 is configured to provide the functionality of a mobile phone case. The housing includes engagement features for coupling the base unit to the communication device (e.g., mobile phone). For example, a receptacle 309 may be formed in the housing for receiving the mobile phone at least partially therein. The receptacle may be on a front side of the housing. The base unit electronics may be provided proximate an opposite side of the receptacle. The coils may be placed around the perimeter of the housing, e.g. along any of the top, bottom, or left and right sides.

With reference now also to FIGS. 6-8, operations of a base unit in accordance with some examples herein will be described. FIG. 6 illustrates a process 400 for wirelessly charging an electronic device 200 which is separate from (e.g., not attached to) the base unit (e.g., base unit 100 or 300). As described, the base unit may be implemented as an attachment member configured for coupling to a communication device, such as a mobile phone 20. The base unit may be integrated into the communication device in other examples. The base unit (e.g., base unit 100 or 300) may be used to charge another device other than the mobile phone 20 to which it is attached, although the present disclosure is not thus limited and charging the mobile phone 20 with the base unit is also envisioned. The mobile phone 20 may be moved to a position in which the mobile phone 20 and base unit (e.g., base unit 100 or 300) attached thereto or incorporated therein are proximate to the electronic device 200 (e.g., eyewear camera 205 in FIG. 8), as shown in block 420. For example, the user 5 may bring the mobile phone 20 near the user's head in order to conduct a call. During this time, the electronic device may in proximity to the base unit (e.g., within the charging range of the base unit) and may wirelessly receive power from the base unit.

The base unit (e.g., base unit 100 or 300) may be configured to selectively transmit power. For example, the base unit may be configured to preserve energy during times when electronic devices are not sufficiently close to the base unit to receive the power signals. The base unit may be configured to stop transmission of power when no compatible electronic devices are detected in proximity.

Prior to initiating power transmission, the base unit (e.g., base unit 100 or 300) may detect an electronic device in proximity, e.g., as shown in block 430. The electronic device may be in proximity for charging while remaining separated by a distance from the base unit. That is, the electronic device may be in proximity for charging even though the electronic device does not contact the base unit. In some examples, the electronic device may broadcast a signal (block 410), which may be detected by the base unit. The signal may be a proximity signal indicating the presence of the electronic device. The signal may be charge status signal, which provides also an indication of the charge level of the power cell within the electronic device. When the electronic device is within a communication range of the base unit, the base unit may detect the signal broadcast by the electronic device and may initiate power transfer in response to said signal. The communication range may be substantially the same as the charging range. In some examples, the communication range may be smaller than the charging range of the base unit to ensure that electronic devices are only detected when well within the charging range of the base unit. The electronic device may remain in proximity as long as a distance between the electronic device remains equal to or less than the threshold distance (e.g., charging range).

In some examples, broadcasting a signal from the electronic device may be impractical, e.g., if limited power is available onboard the electronic device. The base unit may instead transmit an interrogation signal. The interrogation signal may be transmitted continuously or periodically. The electronic device may be configured to send a signal (e.g., proximity signal, charge status signal, charging parameters such as but not limited to, charging frequency, power requirement, and/or coil orientation) responsive to the interrogation signal. In some examples, redundant detection functionality may be included such that both the base unit and the electronic device broadcast signals and the detection is performed according to either of the processes described with reference to blocks 405 and 410.

The base unit (e.g., base unit 100 or 300) may wirelessly transmit power to the electronic device 200 (block 440) while one or more conditions remain true. For example, the base unit may continue to transmit power to the electronic device while the electronic device remains within the charging zone of the base unit or until the power cell of the electronic device is fully charged. With regards to the latter, the electronic device may transmit a charge status signal when the power cell is fully charged and the base unit may terminate broadcast of power signals when the fully charged status signal is detected. In some examples, alternatively or in addition to sending a fully charged status signal, the electronic device may include a charging circuit which is configured to protect the power cell of the electronic device by turning off charging once the power cell is fully charged. In this manner, an individual electronic device may stop receiving power while the base unit continues to transmit, e.g., in the event that multiple devices are being charged.

In some examples, the base unit may be configured to periodically or continuously send interrogation signals while broadcasting power signals. The interrogation signals may trigger response signals from electronic devices 200 in proximity. The response signals may be indicative of whether any electronic devices remain in proximity and/or whether any devices in proximity require power. The base unit may be configured to broadcast power until no electronic devices are detected in proximity or until all charge status signal of electronic device in proximity are indicative of fully charged status.

In some examples, the base unit (e.g., base unit 100 or 300) may be further configured to adjust a mode of power transmission. The base unit may be configured to transmit power in a low power mode, a high power mode, or combinations thereof. The low power mode may correspond to a power transfer mode in which power is broadcast at a first power level. The high power mode may correspond to a power transfer mode in which power is broadcast at a second power level higher than the first power level. The low power mode may correspond with a mode in which power is broadcast at a body-safe level. The base unit may be configured to detect a state of the base unit, as in block 450. For example, a sensor (e.g., an accelerometer, a gyro, or the like) onboard the base unit may detect a change in the position or orientation of the base unit, or a change in acceleration, which may indicate that the base unit is being held or moved towards the user's body. The controller may be configured to determine if the base unit is stationary (block 460) and change the power mode responsive to this determination. For example, if the base unit is determined to be stationary, the base unit may transmit power in high power mode as in block 470. It the base unit is determined not to be stationary, the base unit may reduce the power level of power signals transmitted by the base unit. The base unit may change the mode of power transmission to low power mode, as shown in block 480. The base unit may continue to monitor changes in the state of the base unit and may adjust the power levels accordingly, e.g., increasing power level again to high once the base unit is again determined to be stationary. The sensor may monitor the state of the base unit such that power transmission is optimized when possible while ensuring that power is transmitted at safe levels when appropriate (e.g., when the base unit is moving for example as a result of being carried or brought into proximity to the user's body).

In some examples, the base unit may be communicatively coupled to the communication device (e.g. mobile phone 20). The mobile phone 20 may be configured to execute a software application which may provide a user interface for controlling one or more functions of the base unit. For example, the software application may enable a user 5 to configure power broadcast or interrogation signal broadcast schedules and/or monitor the charge status of the base unit and/or electronic device coupled thereto. The software application may also enable processing of data received by the base unit from the electronic device(s). FIG. 7 illustrates a flow chart of a process 500 for wireless power transfer in accordance with further examples herein. In the example in FIG. 7, the base unit is communicatively coupled to the mobile phone such that the mobile phone may transmit a command signal to the base unit. The command signal may be a command to initiate broadcast of interrogation signals, as shown in block 505. The base unit may transmit an interrogation signal (block 510) responsive to the command signal. Proximity and/or charge status signals may be received from one or more electronic devices in proximity (block 515). Upon detection of an electronic device in proximity, the controller of the base unit may automatically control the transmitter to broadcast power signals (block 520). In some examples, an indication of a detected electronic device may be displayed on the mobile phone display. The mobile phone may transmit a command signal under the direction of a user, which may be a command to initiate power transfer. The base unit may continue to monitor the charge status of the electronic device (e.g., via broadcast of interrogation signals and receipt of responsive charge status signals form the electronic device), as shown in block 525. Broadcast of power from the base unit may be terminated upon the occurrence of an event, as shown in block 530. The event may correspond to receiving an indication of fully charged status from the one or more electronic devices being charged, receiving an indication of depleted stored power in the batter of the base unit, or a determination that no electronic device remain in proximity to the base unit. In some example, the broadcast of power may continue but at a reduced power lever upon a determination that the base unit is in motion (e.g., being carried or moved by a user 5).

As previously described, the base unit may include a plurality of coils and/or a plurality of rods arranged in a pattern. FIG. 9 illustrates a base unit which includes two coils. The base unit may include some or all of the features of the base units in FIGS. 1-8, thus their description will not be repeated. For example, the base unit 700 may include at least one Tx coil 712 and circuitry 705 configured to provide the functionality of a base unit in accordance with the present disclosure. The coils and circuitry 705 may be enclosed or embedded in a housing 715. The base unit 700 includes a first coil 712-1 and a second coil 712-2. In some examples, both the first and the second coils may be configured for wireless power transmission. In some examples, the first coil 712-1 may be configured as a transmitting coil and the second coil 712-2 may be configured as a receiving coil. The first and second coils may extend, at least partially, along opposite sides of the housing 715. For example, the first coil 712-1 may be provided along the top side and the second coil 712-2 may be provided along the bottom side of the housing 715. Terms of orientation, such as top, bottom, left and right, are provided for illustration only and without limitation. For example, the terms top and bottom may indicate orientation of the base unit when coupled to a mobile phone and during typical use, e.g., a top side of the base unit may be closest to the top side of the mobile phone, the bottom side of the base unit closest to the bottom side of the mobile phone, and so on. In some examples, the base unit may alternatively or additionally include coils that are arranged along any side or face of the housing, including the left and right sides, or near the front or back faces of the housing. In some examples, the Tx coils or components thereof may be located in a central portion of the base unit, as will be described further below. The housing includes a receptacle 709 for coupling a communication device (e.g., mobile phone) thereto. The receptacle 709 may include engagement features for mechanically connecting a communication device to the mobile phone. For example, the housing may be made from a rigid plastic material and the receptacle may be configured such that the communication device snaps into engagement with the mobile phone. In some examples, the housing may be made, at least partially, for a resilient plastic material (e.g., rubber) and at least a portion of the housing may be deformed (e.g., elongated or flexed) when placing the mobile phone in the receptacle 709. Additional examples of base unit housings and engagement features are described with reference to FIGS. 10-12 below.

FIG. 10 illustrates a base unit 800 having a housing 815 in the form of a case for a communication device 30. The communication device 30 may be a tablet or smart phone. The housing 815 may enclose the circuitry 801 of the base unit. The housing 815 may include a receptacle 809 which is configured to receive the communication device 30 (e.g., tablet or smart phone). In this example, the receptacle is configured for sliding engagement with the communication device 30, e.g., tablet, by sliding the communication device into the receptacle 809 from a side (e.g., a top side) of the housing. In other examples, the receptacle 809 may be configured for snap engagement with the communication device 30 (e.g., tablet or smart phone). In further examples, the housing 815 may be configured to be resiliently deformed, at least partially, when being attached to the communication device 30. The communication device 30 may be seated in the receptacle 809 with at least a portion of the housing projecting from the base unit 800. In some examples, the communication device 30 may be, at least partially, enclosed by the housing 815 such that the display face 31 of the communication device 30 (e.g., tablet or smart phone) is substantially flush with the front surface 817 of the housing.

FIG. 11 illustrates a base unit 900 having a housing 915 in the form of a partial case for a communication device 15. The communication device 15 may be a mobile phone, a tablet, or the like. The partial case may attach to and/or enclose a portion (e.g., a bottom portion, a top portion) of the communication device 15. The housing 915 may enclose the circuitry 901 of the base unit 900. The base unit 900 may include a receptacle 909 formed in the housing 915. The receptacle 909 may be configured for snap engagement with the communication device 15. By snap engagement, it may be generally implied that one or more engagement features of the receptacle are shaped/sized for an interference fit with at least a portion of the communication device and the one or more engagement features are temporarily deformed to receive the communication device in the receptacle. In other examples, the receptacle 909 may be configured for slidable engagement with the communication device 15 in a manner similar to the example in FIG. 10.

FIG. 12 illustrates a base unit 1000 having a housing 1015 according to further examples herein. The housing 1015 may be similar to housing 915 in that it may be a partial case configured to attach to only a portion of the communication device 15. The housing 1015 may enclose the circuitry 1001 of the base unit 1000. A movable cover 1019 may be attached to the housing 1015. The movable cover 1019 may be hinged at one or more locations to allow the cover 1019 to be moved out of the way to access the communication device 15. In some examples, an attachment member may be coupled to the housing 1015, cover 1019 or both. The attachment member 1003 may be configured to allow the user to conveniently carry the base unit 1000 and communication device 15 attached thereto. For example, the attachment member 1003 may be a clip, a loop or the like, for attaching the base unit to clothing/accessories. The movable cover may be secured in a closed position via a conventional fastener (e.g., a snap, a magnetic closure, or others).

FIGS. 13 and 14 illustrate base units according to further examples of the present disclosure. The base units 1100, 1200 may include some or all of the features of base units described herein and similar aspects will thus not be repeated. For example, the base units 1100, 1200 may include a wireless power transmitter (e.g., Tx coil 1112, 1212), a battery (1120, 1220) and base unit circuitry (1105, 1205). The battery 1120, 1220 and circuitry 1105, 1205 may be provided in a central portion of the base unit 1100, 1200, while the Tx coils 1112, 1212 may be provided along peripheral portions of the base unit 1100, 1200. The battery 1120, 1220 may be rechargeable and/or removable. A housing 1115, 1215 of the base unit may be configured as an attachment member, e.g., for attaching the base unit to a communication device, for example a mobile phone 20. The housing may have perimeter sides (e.g., a top side, bottom side, left and right sides, which are arbitrarily described as top, bottom, left and right to illustrate the relative orientation of the base unit to a mobile phone when coupled thereto). In the examples in FIGS. 13 and 14, the Tx coils are arranged parallel to the perimeter sides (e.g. along peripheral portions) of the base unit.

The transmitter may include a single continuous Tx coil or a segmented Tx coil. In the example in FIG. 13, the transmitter includes a segmented coil including a plurality of discrete Tx coils (in this example four coils 1112-1, 512-2, 512-3, and 512-4), each having a magnetic core with conductive windings wound thereon. A diameter ø of the Tx coils may range from about 5 mm to about 20 mm. In some examples, the diameter ø of the Tx coils may be between 8 mm to 15 mm. In some examples, the diameter ø of the Tx coils may be 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, or 14 mm. Different diameters for the coils may be used. The magnetic cores in this example are implemented as elongate cylindrical rods made from a magnetic material. The rods in this example are arranged around the perimeter of the base unit 1100. In some examples, the rods may extend substantially along the full length of the top side, bottom side, left and right sides of the housing 1115. Lengths (l), widths (w), and thicknesses (t) of the housing 1115 may range from about 150 mm-180 mm, 80-95 mm, and 15-25 mm, respectively. Other lengths, widths, and thicknesses may be used, e.g., to accommodate a given communication device (e.g. smartphone) and/or accommodate a particular coil size. For example, a housing configured to couple to an iPhone 6 mobile phone may be about 160 mm long, about 84 mm wide, and about 19 mm thick and accommodate Tx coils having a diameter of about 9 mm. In another example, the housing may have a length of about 165 mm, a width of about 94 mm, and a thickness of about 21 mm accommodating a coil having a diameter of about 14 mm.

The base unit includes a receptacle 1109, 1209 for receiving the mobile phone 20. In this example, the receptacle is configured to receive the mobile phone such that the mobile phone is substantially flush with a front face of the housing. The receptacle 1109, 1209 may have a size and shape substantially matching the size and shape of the mobile phone such that the mobile phone is substantially enclosed on five sides by the housing. In some examples, the receptacle may have a size and/or shape selected to partially enclose the mobile phone. The mobile phone may project from the housing when engaged thereto (e.g., as illustrated in the examples in FIGS. 10 and 11), which may further reduce the form factor of the base unit.

In some examples, the windings may be spaced from the surface of the rod(s), e.g., as in the examples in FIGS. 15 and 16 described further below.

In some examples, it may be desirable to maximize the number of windings or length of wire used in the windings. A base unit having a generally flattened parallelepiped shape may have four perimeter sides (top, bottom, left and right sides) and two major sides (front and back sides). The number of windings or length of wire used in the windings may maximized by placing the windings at the peripheral portion of the device. For example, the conductive wire may be wound with the loops substantially traversing the perimeter of the base unit (e.g., as defined by the top, bottom, left and right sides. FIG. 15 illustrate examples of base units 1300a-c in which conductive windings 1316 are provided at the perimeter of the base unit and the core material (e.g., core rods 1314) is provided in an interior portion of the base unit spaced from the windings. Base unit 1300a includes individual rods 1314 which are arranged with their centerlines perpendicular to a major side (e.g., front or back side) of the base unit. Base units 1300b and 1300c include individual rods 1314 which are arranged with their centerlines arranged parallel to a perimeter side of the base unit.

In further examples, the conductive wire may be wound such that the wire is in a plane substantially parallel to a major side of the base unit. For example, base unit 1400a includes a core material in the form of a core plate 1417 and windings wrapped around the core plate with the coil axis substantially parallel to the left and right sides of the base unit. Base units 1400b and 1400c includes windings 1416 similar to the windings of base unit 1400a but using discrete rods 1416 as core material, the rods spaced inwardly from the windings and arranged parallel to a perimeter side of the base unit. Non-magnetic material may be provided in the spaces between the rods in the examples in FIGS. 15 and 16. Different combination of orientations of the windings and rods than the specific examples illustrated may be used in other examples.

The base unit may be incorporated in a variety of shapes which may have a relatively small form factor. The base unit may be incorporated into a form factor which is portable, e.g., fits in a user's hand and/or easy to carry in the user's pocket, handbag, or may be attachable to a wearable accessory of the user). For example, referring now also to FIG. 17 base unit 1500 may have a housing 1515 which has a generally cylindrical shape (e.g., puck shape). A puck base unit 1500 may include some or all of the components of base units described herein and the description of such components will not be repeated. For example, the base unit may include a transmitter (e.g. Tx coil 1512) a battery and a controller (not shown). The housing 1515 may have a first major side (e.g., a base) and a second major side (e.g., a top). The Tx coil may be placed along the perimeter (e.g., proximate and extending, at least partially, along the cylindrical perimeter side) of the base unit. In some examples, the core may be in the shape of a cylindrical core plate. The coil windings, cylindrical core plate, and cylindrical puck may be coaxially aligned. The base unit 1500 may include one or more input ports 1560 for connecting the base unit to external power and/or another computing device. For example, the base unit 1500 may include a first input port 1560-1 for coupling AC power thereto and a second input port 1560-2 (e.g., USB port) for coupling the base unit to a computing device, e.g., a laptop or tablet. The base unit 1500 may include one or more charge status indicators 1590. The charge status indicators 1590 may provide visual feedback regarding the status and/or charging cycle of the base unit, the electronic devices in proximity, or combinations thereof.

A charge status indicator in the form of an illumination device 1592 may be provided around the perimeter of the base unit or the perimeter of a major side of the base unit. The illumination device may include a plurality of discrete light sources. Individual ones or groups of individual light sources may provide status indication for individual electronic devices which may be inductively coupled to the base unit for charging. In some examples, an indicator display 1594 may be provided on a major side (e.g., a top side) of the base unit. The indicator display may be configured to provide individual charge status indications for one or more electronic devices inductively coupled to the base unit for charging.

FIG. 18 illustrates components of a transmitter and receiver circuits for a wireless power transfer system in accordance with the present disclosure. On the transmitter side of the system, the transmitting coil is represented by an inductance L11. The transmitter circuit is tuned to broadcast at desired frequency. To that end, the transmitter circuit includes capacitor CIPAR and resistor RIPAR, which may be selected to tune the transmitter to the desired transmit resonance frequency. On the receiver side of the system, the receiving coil is represented by an inductance L22, and capacitor C22 and resistor R2 are chosen to tune the RLC circuit produced by the inductance of the receiving coil and C22 and R2 to the transmit resonance frequency produced by the transmitting coil. A rectifier (e.g. a full wave rectifier) is made from four diodes D1, D2, D3, and D4. The rectifier in combination with the load circuit made up for RLoad, Cload, and Lload and convert the alternating signal induced in L22 to DC voltage output for charging the battery of the device. The load resistor RLoad and the load capacitor CLoad are selected to impedance match the diode bridge to the charging circuit for the battery used in the wearable device.

In some embodiments the transmitting coil and thus the inductance L11 is relatively large compared to the inductance of the receiving coil and its inductance L22. When the transmitting and receiving coils are in close proximity the transfer efficiency is relatively high. At larger distances the efficiency is reduced but remains relatively high compared to other systems, such as a Qi standard compliant systems. This is illustrated in FIGS. 21-23.

In some examples, the shape of the pattern of a magnetic field between inductively coupled transmitting and receiving coils in accordance with the present disclosure may be largely omnidirectional with well-established nulls at the top and bottom of the coils. The radiation pattern can be directed by placing the coil against or near a reflecting ground plane to produce more of a unidirectional pattern.

FIG. 24 illustrates an example of magnetic field lines emanating from a transmitting coil and the field at the receiving coil when the position of the receiving coil is well known or predictable (e.g., in typical use scenarios). In such example, directed flux approach may be used to improve the efficiency of energy transfer.

By careful specification of the use cases for the charging system of the wearable device, a wireless power transfer system can be optimized to produce an improved arrangement of charging conditions while preserving form factor through a reduction of battery size needed to normally charge a device for its typical use period between charging cycles. In some applications, the electronic device may not need to be intentionally placed in a manner to facilitate charging, since the power transmitted at the use case distance may be adequate for maintaining the energy draw from the system on the battery.

The above detailed description of examples is not intended to be exhaustive or to limit the method and system for wireless power transfer to the precise form disclosed above. While specific embodiments of, and examples for, the method and systems for wireless power transfer are described above for illustrative purposes, various equivalent modifications are possible within the scope of the system, as those skilled in the art will recognize. For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines having operations, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified. While processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times. It will be further appreciated that one or more components of base units, electronic devices, or systems in accordance with specific examples may be used in combination with any of the components of base units, electronic devices, or systems of any of the examples described herein.

Claims

1. A base unit comprising: a transmitter configured for wireless power delivery, the transmitter comprising a coil comprising a magnetic core;a battery coupled to the transmitter;a controller coupled to the battery and the transmitter and configured to cause the transmitter to selectively transmit power from the battery to an electronic device separated from the base unit; anda housing enclosing the transmitter, the battery, and the controller, the housing configured to be mechanically coupled to a mobile phone.

2. The base unit of claim 1, wherein the magnetic core comprises a ferrite core.

3. The base unit of claim 2, wherein the ferrite core is curved along a longitudinal direction of the coil.

4. The base unit of claim 1, wherein the base unit is enclosed in a housing having a circular shape.

5. The base unit of claim 1, wherein the coil is disposed along a perimeter of the housing.

6. The base unit of claim 1, wherein the transmitter of the base unit comprises a plurality of coils.

7. The base unit of claim 6, wherein the plurality of coils are arranged along a perimeter of the base unit.

8. The base unit of claim 1, wherein the base unit further comprises a receiver, the receiver configured to wirelessly receive power, data, or combinations thereof.

9. The base unit of claim 8, wherein the base unit further comprises a memory, wherein the receiver is communicatively coupled to the memory and configured to receive data from the electronic device for storing the data in the memory.

10. The base unit of claim 1, wherein the base unit further comprises a memory, and wherein the transmitter is communicatively coupled to the memory and configured to transfer data from the memory to the electronic device.

11. The base unit of claim 1, wherein the transmitter comprises an omnidirectional antenna configured to wirelessly transmit power to one or more electronic devices positioned around the base unit.

12. The base unit of claim 1, wherein the base unit further comprises a wired input for charging to the battery.

13. The base unit of claim 1, wherein the wired input comprises a micro USB port.

14. The base unit of claim 1, further comprising a sensor configured to detect a change in orientation of the base unit, the controller configured to cause the transmitter to reduce a power output from the transmitter responsive to the change in orientation of the base unit.

15. A system comprising: a base unit comprising a transmitter configured for wireless power delivery and a battery coupled to the transmitter, wherein the transmitter comprises a transmitting coil having a magnetic core; andan electronic device separated from the base unit, the electronic device comprising a receiver inductively coupled to the transmitter to receive power from the base unit while the electronic device remains within a threshold distance from the base unit, wherein the receiver comprises a receiving coil having a magnetic core, wherein a dimension of the transmitting coil is at least twice a dimension of the receiving coil.

16. The system of claim 15, wherein the base unit is mechanically coupled to a cellphone, the base unit further configured to provide power wirelessly to the cellphone.

17. The system of claim 15, wherein the base unit is electrically coupled to a cellphone, the base unit further configured to receive power from a battery of the cellphone and transmit the power wirelessly to the electronic device separated from the base unit.

18. The system of claim 15, wherein the transmitter comprises an omnidirectional antenna configured to transmit power to one or more electronic devices regardless of orientation of the electronic devices with respect to the base unit.

19. The system of claim 15, wherein: the dimension of the transmitting coil is a diameter of the transmitting coil, a length or a diameter of a wire forming windings of the transmitting coil, a number of windings of the transmitting coil, or a length, a diameter or a surface area of the core of the transmitting coil; and the dimension of the receiving coil is respectively a diameter of the receiving coil, a length or a diameter of a wire forming windings of the receiving coil, a number of windings of the receiving coil, or a length, a diameter or a surface area of the core of the receiving coil.

20. The system of claim 15, wherein the transmitter of the base unit comprises a transmitting coil and the receiver comprises a receiving coil, wherein a dimension of the transmitting coil is smaller than a dimension of the receiving coil by at least 50%.

21. The system of claim 15, wherein the electronic device is an eyewear camera configured to be attached to a track incorporated in an eyewear frame.

22. A method comprising: moving a mobile phone to a position proximate an electronic device, wherein a base unit is attached to the mobile phone and wherein the electronic device is not attached to the mobile phone, the base unit comprising a transmitting coil for wirelessly transmitting power to a receiving coil on the electronic device, and wherein the position proximate an electronic device is defined by a distance between the base unit and the electronic device less than a charging range of the base unit;detecting the electronic device with the base unit or the mobile phone; andwirelessly transmitting power signals to the electronic device while the electronic device remains within the charging range of the base unit or until a charge state signal of the electronic device corresponds to a fully charged state of the electronic device.

23. The method of claim 22, wherein the moving a mobile phone to a position proximate an electronic device comprises moving the mobile phone to a position in which an axis of the transmitting coil is angled from about 5 degrees to about 90 degrees relative to an axis of the receiving coil.

24. The method of claim 22, wherein the detecting the electronic device comprises automatically detecting a signal broadcast by the electronic device.

25. The method of claim 22, wherein the signal broadcast by the electronic device comprises a proximity signal of the electronic device, a charge state signal of the electronic device, or combinations thereof.

26. The method of claim 22, wherein the detecting the electronic device comprises automatically detecting a signal from the electronic device transmitted responsive to an interrogation signal from the base unit.

27. The method of claim 26, further comprising periodically broadcasting the interrogation signal from the base unit.

28. The method of claim 26, further comprising transmitting the interrogation signal from the base unit responsive to a command signal received from the mobile phone.

29. The method of claim 22, further comprising detecting a change in a state of the base unit and reducing a power level of power signals broadcast by the base unit responsive to the change in the status.

30. The method of claim 29, wherein detecting a change in a state of the base unit comprises detecting a change in orientation or a change in acceleration of the base unit.

31. The method of claim 29, wherein the reducing a power level of power signals broadcast by the base unit comprises reducing the power level to a body-safe level.

32. The method of claim 29, further comprising increasing the power level of power signals broadcast by the base unit if a detected state of the base unit is indicative of the base unit being stationary.

33. A wireless energy transfer system comprising: a transmitter of wireless power located within a mobile phone;a distance separated receiver located within an electronic wearable device other than the mobile phone, wherein the receiver is configured to receive power energy from the transmitter.

34. The wireless energy transfer system of claim 33, wherein the transmitter includes a magnetic material.

35. The wireless energy transfer system of claim 33, wherein the receiver includes a magnetic material.

36. The wireless energy transfer system of claim 33, wherein the transmitter includes a coil and a core.

37. The wireless energy transfer system of claim 33, wherein the receiver includes a coil and a core.

38. The wireless energy transfer system of claim 33, wherein transmitter and receiver are configured for operation with a Q value less than 100.

39. The wireless energy transfer system of claim 33, wherein the distance separation is greater than 1 mm.

40. The wireless energy transfer system of claim 33, wherein the distance separation is greater than 10 mm.

41. The wireless energy transfer system of claim 33, wherein the distance separation is greater than 100 mm.

42. The wireless energy transfer system of claim 33, wherein the distance separation is greater than 1000 mm.

43. A wireless energy transfer system comprising: a base unit comprising a transmitter comprising a first coil and a first magnetic core; anda distance separated electronic device comprising a receiver comprising a second coil and second magnetic core, wherein a dimension of the first coil or first core is two times or greater a same dimension of the second coil or second core,wherein the system is configured to operate at a frequency within the range of 50 kHz or 500 kHz, wherein the transmitter and the receiver are configured to operate in weak resonance, and wherein the system is configured to operate using an amount of guided flux.

44. The wireless energy transfer system of claim 43, wherein a Q value of the system is less than 100.

45. The wireless energy transfer system of claim 43, wherein the frequency is within a range of 75 kHz to 200 kHz.

46. The wireless energy transfer system of claim 43, wherein the first magnetic core, the second magnetic core, or both are ferrite cores.

47. The wireless energy transfer system of claim 43, wherein the first coil, the second coil, or both comprise windings of multi-strand wire.

48. The wireless energy transfer system of claim 43, wherein the guided flux is a partially guided flux.