U.S. patent application number 16/952055 was filed with the patent office on 2021-05-20 for free-position wireless charger keep-out.
The applicant listed for this patent is AIRA Inc.. Invention is credited to Eric Heindel Goodchild, John Winters.
Application Number | 20210152034 16/952055 |
Document ID | / |
Family ID | 1000005261984 |
Filed Date | 2021-05-20 |
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United States Patent
Application |
20210152034 |
Kind Code |
A1 |
Goodchild; Eric Heindel ; et
al. |
May 20, 2021 |
Free-Position Wireless Charger Keep-Out
Abstract
Systems, methods and apparatus for wireless charging are
disclosed. One method for operating a charging device includes
determining that a chargeable device is positioned proximate to a
charging coil provided by a charging surface, providing a charging
current to the charging coil, and excluding adjacent coils from
operation while the current is provided to the charging coil. Each
of the adjacent coils is located within the charging surface
adjacent to the charging coil. The adjacent coils may be excluded
from participating in one or more device discovery procedures. The
charging device may refrain from providing charging current to the
adjacent coils while the current is provided to the charging
coil.
Inventors: |
Goodchild; Eric Heindel;
(Phoenix, AZ) ; Winters; John; (San Diego,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIRA Inc. |
Chandler |
AZ |
US |
|
|
Family ID: |
1000005261984 |
Appl. No.: |
16/952055 |
Filed: |
November 18, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62938308 |
Nov 20, 2019 |
|
|
|
63066315 |
Aug 16, 2020 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 50/402 20200101;
H02J 50/80 20160201; H02J 50/10 20160201 |
International
Class: |
H02J 50/80 20060101
H02J050/80; H02J 50/10 20060101 H02J050/10; H02J 50/40 20060101
H02J050/40 |
Claims
1. A method for operating a wireless charging device, comprising:
determining that a chargeable device is positioned proximate to a
charging coil provided at a charging surface of the wireless
charging device; providing a charging current to the charging coil;
and excluding a plurality of adjacent coils from operation while
the current is provided to the charging coil, wherein each of the
adjacent coils is located on the charging surface adjacent to the
charging coil.
2. The method of claim 1, further comprising: excluding the
plurality of adjacent coils from participating in one or more
device discovery procedures.
3. The method of claim 2, wherein the one or more device discovery
procedures include a discovery procedure involving differential
capacitive sense.
4. The method of claim 2, wherein the one or more device discovery
procedures include a passive ping discovery procedure.
5. The method of claim 2, wherein the one or more device discovery
procedures include an active ping discovery procedure.
6. The method of claim 1, wherein excluding the plurality of
adjacent coils from operation comprises: refraining from providing
charging current to the plurality of adjacent coils while the
current is provided to the charging coil.
7. The method of claim 1, wherein excluding the plurality of
adjacent coils from operation comprises: blocking wireless
communication through the plurality of adjacent coils while the
current is provided to the charging coil.
8. The method of claim 1, wherein the plurality of adjacent coils
includes coils located on or within a circle that is concentric
with the charging coil.
9. The method of claim 1, wherein the plurality of adjacent coils
is arranged around a footprint of the chargeable device on the
charging surface.
10. The method of claim 1, wherein determining that the chargeable
device is positioned proximate to the charging coil comprises:
detecting the chargeable device during a device discovery procedure
that includes differential capacitive sense, passive ping or active
ping.
11. A processor-readable storage medium comprising code that, when
executed by a processor, cause the processor to: determine that a
chargeable device is positioned proximate to a charging coil
provided at a charging surface of a wireless charging device;
provide a charging current to the charging coil; and exclude a
plurality of adjacent coils from operation while the current is
provided to the charging coil, wherein each of the adjacent coils
is located on the charging surface adjacent to the charging
coil.
12. The processor-readable storage medium of claim 11, further
comprising code that causes the processor to: exclude the plurality
of adjacent coils from participating in one or more device
discovery procedures when the plurality of adjacent coils is
excluded from operation.
13. The processor-readable storage medium of claim 12, wherein the
one or more device discovery procedures include a passive ping
discovery procedure.
14. The processor-readable storage medium of claim 12, wherein the
one or more device discovery procedures include an active ping
discovery procedure.
15. The processor-readable storage medium of claim 11, further
comprising code that causes the processor to: refrain from
providing charging current to the plurality of adjacent coils while
the current is provided to the charging coil and when the plurality
of adjacent coils is excluded from operation.
16. The processor-readable storage medium of claim 11, further
comprising code that causes the processor to: block wireless
communication through the plurality of adjacent coils while the
current is provided to the charging coil when the plurality of
adjacent coils is excluded from operation.
17. A wireless charging device, comprising: a charging surface
comprising a plurality of charging cells; one or more wireless
transmitter circuits each configured to be selectively coupled to
one or more of the plurality of charging cells; and a controller
configured to: determine that a chargeable device is positioned
proximate to a charging coil provided at a charging surface of the
wireless charging device; provide a charging current to the
charging coil; and exclude a plurality of adjacent coils from
operation while the current is provided to the charging coil,
wherein each of the adjacent coils is located on the charging
surface adjacent to the charging coil.
18. The wireless charging device of claim 17, wherein the
controller configured to: exclude the plurality of adjacent coils
from participating in one or more device discovery procedures when
the plurality of adjacent coils is excluded from operation.
19. The wireless charging device of claim 17, wherein the
controller configured to: refrain from providing charging current
to the plurality of adjacent coils while the current is provided to
the charging coil and when the plurality of adjacent coils is
excluded from operation.
20. The wireless charging device of claim 17, wherein the
controller configured to: block wireless communication through the
plurality of adjacent coils while the current is provided to the
charging coil when the plurality of adjacent coils is excluded from
operation.
Description
PRIORITY CLAIM
[0001] This application claims priority to and the benefit of
provisional patent application No. 62/938,308 filed in the United
States Patent Office on Nov. 20, 2019 and of provisional patent
application No. 63/066,315 filed in the United States Patent Office
on Aug. 16, 2020, the entire content of these applications being
incorporated herein by reference as if fully set forth below in
their entirety and for all applicable purposes.
TECHNICAL FIELD
[0002] The present invention relates generally to wireless charging
of batteries, including batteries in mobile computing devices and
more particularly to preventing interference from pings used by a
wireless charging device to locate a first device while the
wireless charging device is actively charging a second device.
BACKGROUND
[0003] Wireless charging systems have been deployed to enable
certain types of devices to charge internal batteries without the
use of a physical charging connection. Devices that can take
advantage of wireless charging include mobile processing devices
and mobile communication devices. Standards, such as the Qi
standard defined by the Wireless Power Consortium enable devices
manufactured by a first supplier to be wirelessly charged using a
charger manufactured by a second supplier. Standards for wireless
charging are optimized for relatively simple configurations of
devices and tend to provide basic charging capabilities.
[0004] Conventional wireless charging systems typically use a
"Ping" or "digital ping" to determine if a receiving device is
present on or proximate to a transmitting coil in a base station
for wireless charging. The transmitter coil has an inductance (L)
and a resonant capacitor that has a capacitance (C) that is coupled
to the transmitting coil to obtain a resonant LC circuit. A Ping is
produced by delivering power to the resonant LC circuit. Power is
applied for a duration of time (90 ms in one example) while the
transmitter listens for a response from a receiving device. The
response may be provided in a signal encoded using Amplitude Shift
Key (ASK) modulation. This conventional Ping-based approach can be
slow due to the 90 ms duration, and can dissipate large and
significant amount of energy, which may amount to 80 mJ per
Ping.
[0005] In one example, a typical transmitting base station may ping
as fast as 12.5 times a second (period=1/80 ms) with a power
consumption of (80 mJ*12.5) per second=1 W. In practice, most
designs trade off responsiveness for a lower quiescent power draw
by lowering the ping rate. As an example, a transmitter may ping 5
times a second with a resultant power draw of 400 mW.
[0006] A base station that has a single transmitting coil ceases
Ping-based discovery when a chargeable device has an established
presence and is receiving power through the transmitting coil.
However, a multi-coil free position charging pad may continue
Ping-based discovery after one or more chargeable devices are
established on the charging pad and receiving power through
different charging cells or transmitting coils. A Ping transmitted
through a first transmitting coil to a newly discovered device, or
to a device in motion, may interfere with a nearby device that is
already receiving power form a second transmitting coil of the
charging pad. For example, flux from the first transmitting coil
can couple with the second transmitting coil or with the receiving
coil in the already-established chargeable device. This coupling
can disrupt communication with the already-established chargeable
device and change the power transferred to the already-established
chargeable device.
[0007] Improvements in wireless charging capabilities are required
to support continually increasing complexity of multi-coil free
position charging pads and their operating conditions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 illustrates an example of a charging cell that may be
provided on a charging surface in accordance with certain aspects
disclosed herein.
[0009] FIG. 2 illustrates an example of an arrangement of charging
cells provided on a single layer of a segment of a charging surface
that may be adapted in accordance with certain aspects disclosed
herein.
[0010] FIG. 3 illustrates an example of an arrangement of charging
cells when multiple layers are overlaid within a segment of a
charging surface that may be adapted in accordance with certain
aspects disclosed herein.
[0011] FIG. 4 illustrates the arrangement of power transfer areas
provided on a charging surface by a charging device that employs
multiple layers of charging cells configured in accordance with
certain aspects disclosed herein.
[0012] FIG. 5 illustrates a wireless transmitter that may be
provided in a charger base station in accordance with certain
aspects disclosed herein.
[0013] FIG. 6 illustrates a first example of a response to a
passive ping in accordance with certain aspects disclosed
herein.
[0014] FIG. 7 illustrates a second example of a response to a
passive ping in accordance with certain aspects disclosed
herein.
[0015] FIG. 8 illustrates examples of observed differences in
responses to a passive ping in accordance with certain aspects
disclosed herein.
[0016] FIG. 9 is a flowchart that illustrates a power transfer
management procedure that may be employed by a wireless charging
device implemented in accordance with certain aspects disclosed
herein.
[0017] FIG. 10 illustrates a topology that supports direct current
drive in a wireless charger adapted in accordance with certain
aspects disclosed herein.
[0018] FIG. 11 illustrates certain charging configurations for a
chargeable device located on a surface of a charging device
provided in accordance with certain aspects disclosed herein.
[0019] FIG. 12 illustrates coils disabled by certain charging
configurations for a chargeable device located on a surface of a
charging device provided in accordance with certain aspects
disclosed herein.
[0020] FIG. 13 is flowchart illustrating an example of a method for
detecting an object performed by a controller provided in a
wireless charging apparatus adapted in accordance with certain
aspects disclosed herein.
[0021] FIG. 14 illustrates one example of an apparatus employing a
processing circuit that may be adapted according to certain aspects
disclosed herein.
DETAILED DESCRIPTION
[0022] The detailed description set forth below in connection with
the appended drawings is intended as a description of various
configurations and is not intended to represent the only
configurations in which the concepts described herein may be
practiced. The detailed description includes specific details for
the purpose of providing a thorough understanding of various
concepts. However, it will be apparent to those skilled in the art
that these concepts may be practiced without these specific
details. In some instances, well known structures and components
are shown in block diagram form in order to avoid obscuring such
concepts.
[0023] Several aspects of wireless charging systems will now be
presented with reference to various apparatus and methods. These
apparatus and methods will be described in the following detailed
description and illustrated in the accompanying drawing by various
blocks, modules, components, circuits, steps, processes,
algorithms, etc. (collectively referred to as "elements"). These
elements may be implemented using electronic hardware, computer
software, or any combination thereof. Whether such elements are
implemented as hardware or software depends upon the particular
application and design constraints imposed on the overall
system.
[0024] By way of example, an element, or any portion of an element,
or any combination of elements may be implemented with a
"processing system" that includes one or more processors. Examples
of processors include microprocessors, microcontrollers, digital
signal processors (DSPs), field programmable gate arrays (FPGAs),
programmable logic devices (PLDs), state machines, gated logic,
discrete hardware circuits, and other suitable hardware configured
to perform the various functionality described throughout this
disclosure. One or more processors in the processing system may
execute software. Software shall be construed broadly to mean
instructions, instruction sets, code, code segments, program code,
programs, subprograms, software modules, applications, software
applications, software packages, routines, subroutines, objects,
executables, threads of execution, procedures, functions, etc.,
whether referred to as software, firmware, middleware, microcode,
hardware description language, or otherwise. The software may
reside on a processor-readable storage medium. A processor-readable
storage medium, which may also be referred to herein as a
computer-readable medium may include, by way of example, a magnetic
storage device (e.g., hard disk, floppy disk, magnetic strip), an
optical disk (e.g., compact disk (CD), digital versatile disk
(DVD)), a smart card, a flash memory device (e.g., card, stick, key
drive), Near Field Communications (NFC) token, random access memory
(RAM), read only memory (ROM), programmable ROM (PROM), erasable
PROM (EPROM), electrically erasable PROM (EEPROM), a register, a
removable disk, a carrier wave, a transmission line, and any other
suitable medium for storing or transmitting software. The
computer-readable medium may be resident in the processing system,
external to the processing system, or distributed across multiple
entities including the processing system.
[0025] Computer-readable medium may be embodied in a
computer-program product. By way of example, a computer-program
product may include a computer-readable medium in packaging
materials. Those skilled in the art will recognize how best to
implement the described functionality presented throughout this
disclosure depending on the particular application and the overall
design constraints imposed on the overall system.
Overview
[0026] Certain aspects of the present disclosure relate to systems,
apparatus and methods applicable to wireless charging devices and
techniques. In a wireless charging device, charging cells may be
configured with one or more inductive coils to provide a charging
surface that can charge one or more devices wirelessly. The
location of a device to be charged may be detected through sensing
techniques that associate location of the device to changes in a
physical characteristic centered at a known location on the
charging surface. Sensing of location may be implemented using
capacitive, resistive, inductive, touch, pressure, load, strain,
and/or another appropriate type of sensing.
[0027] In one aspect of the disclosure, an apparatus has a battery
charging power source, a plurality of charging cells configured in
a matrix. Each charging cell in the plurality of charging cells may
include one or more coils surrounding a power transfer area. The
plurality of charging cells may be arranged adjacent to a charging
surface without overlap of power transfer areas of the charging
cells in the plurality of charging cells.
[0028] Certain aspects of the present disclosure relate to systems,
apparatus and methods for wireless charging using stacked coils
that can charge target devices presented to a charging device
without a requirement to match a particular geometry or location
within a charging surface of the charging device. Each coil may
have a shape that is substantially polygonal. In one example, each
coil may have a hexagonal shape. Each coil may be implemented using
wires, printed circuit board traces and/or other connectors that
are provided in a spiral. Each coil may span two or more layers
separated by an insulator or substrate such that coils in different
layers are centered around a common axis.
[0029] According to certain aspects disclosed herein, power can be
wirelessly transferred to a receiving device located anywhere on a
charging surface, which can have an arbitrarily defined size and/or
shape without regard to any discrete placement locations enabled
for charging. Multiple devices can be simultaneously charged on a
single charging surface. The charging surface may be manufactured
using printed circuit board technology, at low cost and/or with a
compact design.
[0030] One aspect of the present disclosure relates to systems,
apparatus and methods that prevent or restrict interference caused
by digital pings. A digital ping may also be referred to as an
"active ping" and may be transmitted in accordance with a protocol
or standard. A digital ping may be transmitted from a charging cell
with a power level sufficient to cause coupling of electromagnetic
flux with a neighboring or nearby charging cell. In one example,
interference may be caused when electromagnetic flux transmitted as
part of the digital ping is coupled with a power transmitting coil
that is actively transmitting power through a charging surface of a
wireless charging device. In another example, interference may be
caused when electromagnetic flux transmitted as part of the digital
ping is coupled with a power receiving coil in a device that is
receiving power through the charging surface of the wireless
charging device. Interference can be avoided by excluding charging
cells located near an actively transmitting charging cell from
participation in device discovery procedures.
[0031] In one aspect of this disclosure, a wireless charging device
may be configured to determine that a chargeable device is
positioned proximate to a charging coil provided by a charging
surface, provide a charging current to the charging coil and
exclude a plurality of adjacent coils from operation while the
current is provided to the charging coil. Each of the adjacent
coils is located within the charging surface adjacent to the
charging coil. Adjacent coils may be excluded from operation by
excluding the plurality of adjacent coils from participating in one
or more device discovery procedures, including digital pings.
Adjacent coils may be excluded from operation by excluding the
plurality of adjacent coils from participating in charging a
different chargeable device.
Charging Cells
[0032] According to certain aspects disclosed herein, a charging
device may provide a charging surface using charging cells that are
deployed adjacent to the charging surface. In one example, the
charging cells are deployed in one or more layers of the charging
surface in accordance with a honeycomb packaging configuration. A
charging cell may be implemented using one or more coils that can
each induce a magnetic field along an axis that is substantially
orthogonal to the charging surface adjacent to the coil. In this
description, a charging cell may refer to an element having one or
more coils where each coil is configured to produce an
electromagnetic field that is additive with respect to the fields
produced by other coils in the charging cell, and directed along or
proximate to a common axis.
[0033] In some implementations, a charging cell includes coils that
are stacked along a common axis and/or that overlap such that they
contribute to an induced magnetic field substantially orthogonal to
the charging surface. In some implementations, a charging cell
includes coils that are arranged within a defined portion of the
charging surface and that contribute to an induced magnetic field
within the substantially orthogonal portion of the charging surface
associated with the charging cell. In some implementations,
charging cells may be configurable by providing an activating
current to coils that are included in a dynamically-defined
charging cell. For example, a charging device may include multiple
stacks of coils deployed across the charging surface, and the
charging device may detect the location of a device to be charged
and may select some combination of stacks of coils to provide a
charging cell adjacent to the device to be charged. In some
instances, a charging cell may include, or be characterized as a
single coil. However, it should be appreciated that a charging cell
may include multiple stacked coils and/or multiple adjacent coils
or stacks of coils. The coils may be referred to herein as charging
coils, wireless charging coils, transmitter coils, transmitting
coils, power transmitting coils, power transmitter coils, or the
like.
[0034] FIG. 1 illustrates an example of a charging cell 100 that
may be deployed and/or configured to provide a charging surface of
a charging device. As described herein, the charging surface may
include an array of charging cells 100 provided on one or more
substrates 106. A circuit comprising one or more integrated
circuits (ICs) and/or discrete electronic components may be
provided on one or more of the substrates 106. The circuit may
include drivers and switches used to control currents provided to
coils used to transmit power to a receiving device. The circuit may
be configured as a processing circuit that includes one or more
processors and/or one or more controllers that can be configured to
perform certain functions disclosed herein. In some instances, some
or all of the processing circuit may be provided external to the
charging device. In some instances, a power supply may be coupled
to the charging device.
[0035] The charging cell 100 may be provided in close proximity to
an outer surface area of the charging device, upon which one or
more devices can be placed for charging. The charging device may
include multiple instances of the charging cell 100. In one
example, the charging cell 100 has a substantially hexagonal shape
that encloses one or more coils 102, which may be constructed using
conductors, wires or circuit board traces that can receive a
current sufficient to produce an electromagnetic field in a power
transfer area 104. In various implementations, some coils 102 may
have a shape that is substantially polygonal, including the
hexagonal charging cell 100 illustrated in FIG. 1. Other
implementations provide coils 102 that have other shapes. The shape
of the coils 102 may be determined at least in part by the
capabilities or limitations of fabrication technology, and/or to
optimize layout of the charging cells on a substrate 106 such as a
printed circuit board substrate. Each coil 102 may be implemented
using wires, printed circuit board traces and/or other connectors
in a spiral configuration. Each charging cell 100 may span two or
more layers separated by an insulator or substrate 106 such that
coils 102 in different layers are centered around a common axis
108.
[0036] FIG. 2 illustrates an example of an arrangement 200 of
charging cells 202 provided on a single layer of a segment of a
charging surface of a charging device that may be adapted in
accordance with certain aspects disclosed herein. The charging
cells 202 are arranged according to a honeycomb packaging
configuration. In this example, the charging cells 202 are arranged
end-to-end without overlap. This arrangement can be provided
without through-hole or wire interconnects. Other arrangements are
possible, including arrangements in which some portion of the
charging cells 202 overlap. For example, wires of two or more coils
may be interleaved to some extent.
[0037] FIG. 3 illustrates an example of an arrangement of charging
cells from two perspectives 300, 310 when multiple layers are
overlaid within a segment of a charging surface that may be adapted
in accordance with certain aspects disclosed herein. Layers of
charging cells 302, 304, 306, 308 are provided within a segment of
a charging surface. The charging cells within each layer of
charging cells 302, 304, 306, 308 are arranged according to a
honeycomb packaging configuration. In one example, the layers of
charging cells 302, 304, 306, 308 may be formed on a printed
circuit board that has four or more layers. The arrangement of
charging cells 100 can be selected to provide complete coverage of
a designated charging area that is adjacent to the illustrated
segment.
[0038] FIG. 4 illustrates the arrangement of power transfer areas
provided in a charging surface 400 that employs multiple layers of
charging cells configured in accordance with certain aspects
disclosed herein. The illustrated charging surface is constructed
from four layers of charging cells 402, 404, 406, 408, which may
correspond to the layers of charging cells 302, 304, 306, 308 in
FIG. 3. In FIG. 4, each power transfer area provided by a charging
cell in the first layer of charging cells 402 is marked "L1", each
power transfer area provided by a charging cell in the second layer
of charging cells 404 is marked "L2", each power transfer area
provided by a charging cell in the third layer of charging cells
406 is marked "L3", and each power transfer area provided by a
charging cell in the fourth layer of charging cells 408 is marked
"L4".
Locating Devices on a Charging Surface
[0039] In accordance with certain aspects disclosed herein,
location sensing may rely on changes in some property of the
electrical conductors that form coils in a charging cell.
Measurable differences in properties of the electrical conductors
may include capacitance, resistance, inductance and/or temperature.
In some examples, loading of the charging surface can affect the
measurable resistance of a coil located near the point of loading.
In some implementations, sensors may be provided to enable location
sensing through detection of changes in touch, pressure, load
and/or strain.
[0040] Certain aspects disclosed herein provide apparatus and
methods that can sense the location of devices that are freely
positioned on a charging surface. Location sensing may be
accomplished using low-power differential capacitive sense
techniques that can detect changes in capacitance of a coil in a
charging cell. Differential capacitive sense can be used to
determine location by first connecting two adjacent coils to the
capacitive sense circuitry. Using these two coils the circuitry
measures the capacitance through the use of one or more known
methods. A first method includes applying a constant current
waveform and calculating capacitance based on changes in voltage
sensed by a measuring circuit. Calculation of capacitance can be
based on the following equations:
Q=C*V,
Q=I*t.
[0041] If a known charge is delivered (Q) by sourcing a known
constant current (I) for a specified amount of time (t),
measurements of the voltage (V) can be used to calculate the
capacitance (C). Measured capacitance can be compared to the last
recorded measured value. Certain changes in capacitance are
significant enough to indicate that the system has changed,
enabling detection that something has become part of the system
(e.g., a chargeable wireless telephone).
[0042] Changes in capacitance can be measured through the use of an
RC time constant. A constantly varying square wave signal can be
applied across a known resistance (R) and the unknown capacitance
(C or Cx). The time to charge/discharge can them be measured using
a timer and comparator. By using the time constant equation,
capacitance can be calculated.
[0043] When a search identifies a potential device placement on the
charging surface, the charging device may begin a ping procedure to
identify a charging cell, a combination of charging cells and/or a
combination of coils that are to be activated to charge the device
placed on the charging surface. The ping procedure verifies that
the device to be charged is compatible with the charging device and
may identify a signal strength indicating whether the coils used to
transmit the ping are best positioned for the requested or desired
charging procedure.
[0044] Significant power savings can be achieved when a search is
conducted to locate a device placed on or near in a multi-coil,
free position charging pad before using pings to establish that the
device is configured to receive charge from a wireless charging
device. The savings in power consumption can be obtained by
refraining from providing pings until a device is detected in a
search, and by limiting ping transmissions to transmitting coils
that are placed in proximity to the detected device and likely to
be capable of establishing an electromagnetic charging connection
with the detected device.
[0045] Wireless charging devices may be adapted in accordance with
certain aspects disclosed herein to support a low-power discovery
technique that can replace and/or supplement conventional ping
transmissions. A conventional ping is produced by driving a
resonant LC circuit that includes a transmitting coil of a base
station. The base station then waits for an ASK-modulated response
from the receiving device. The receiving device may modulate the
current or voltage in a resonant circuit by modifying a reactive
component in accordance with a signal to be modulated.
[0046] A low-power discovery technique may include utilizing a
passive ping to provide fast and/or low-power discovery. According
to certain aspects, a passive ping may be produced by driving a
network that includes the resonant LC circuit with a fast pulse
that includes a small amount of energy. The fast pulse excites the
resonant LC circuit and causes the network to oscillate at its
natural resonant frequency until the injected energy decays and is
dissipated. In one example, the fast pulse may have a duration
corresponding to a half cycle of the resonant frequency of the
network and/or the resonant LC circuit. When the base station is
configured for wireless transmission of power within the frequency
range 100 kHz to 200 kHz, the fast pulse may have a duration that
is less than 2.5 .mu.s. In other examples, the fast pulse may have
a duration corresponding to multiple cycles of the resonant
frequency of the network and/or the resonant LC circuit.
[0047] The passive ping may be characterized and/or configured
based on the natural frequency at which the network including the
resonant LC circuit rings, and the rate of decay of energy in the
network. The ringing frequency of the network and/or resonant LC
circuit may be defined as:
.omega. = 1 L C ( Eq . 1 ) ##EQU00001##
[0048] The rate of decay is controlled by the quality factor (Q
factor) of the oscillator network, as defined by:
Q = 1 R L C ( Eq . 2 ) ##EQU00002##
[0049] Equations 1 and 2 show that resonant frequency is affected
by L and C, while the Q factor is affected by L, C and R. In a base
station provided in accordance with certain aspects disclosed
herein, the wireless driver can have a fixed value of C as
determined by the selection of the resonant capacitor. The values
of L and R are determined by the wireless transmitting coil and by
an object or device placed adjacent to the wireless transmitting
coil.
[0050] The wireless transmitting coil is configured to be
magnetically coupled with a receiving coil in a device to be
charged that is placed within close proximity of the transmitting
coil, and to couple some of its energy into the device to be
charged. The L and R values of the transmitter circuit can be
affected by the characteristics of the device to be charged, and/or
other objects within close proximity of the transmitting coil. As
an example, if a piece of ferrous material with a high magnetic
permeability placed near the transmitter coils can increase the
total inductance (L) of the transmitter coil, resulting in a lower
resonant frequency, as shown by Equation 1. Some energy may be lost
through heating of materials due to eddy current induction, and
these losses may be characterized as an increase in the value of R
thereby lowering the Q factor, as shown by Equation 2.
[0051] A wireless receiver placed in close proximity to the
transmitter coil can also affect the Q factor and resonant
frequency. The receiver may include a tuned LC network with a high
Q which can result in the transmitter coil having a lower Q factor.
The resonant frequency of the transmitter coil may be reduced due
to the addition of the magnetic material in the receiver, which is
now part of the total magnetic system. Table 1 illustrates certain
effects attributable to different types of objects placed within
close proximity to the transmitter coil.
TABLE-US-00001 TABLE 1 Object L R Q Frequency None present Base
Value Base value Base Value (High) Base Value Ferrous Small
Increase Large Increase Large Decrease Small Decrease Non-ferrous
Small Decrease Large Increase Large Decrease Small Increase
Wireless Receiver Large Increase Small Decrease Small Decrease
Large Decrease
[0052] FIG. 5 illustrates a wireless transmitter 500 that may be
provided in a charger base station. A controller 502 may receive a
feedback signal that is filtered or otherwise processed by a
conditioning circuit 508. The controller may control the operation
of a driver circuit 504 that provides an alternating current to a
resonant circuit 506 that includes a capacitor 512 and inductor
514. The resonant circuit 506 may also be referred to herein as a
tank circuit, LC tank circuit, or LC tank, and the voltage 516
measured at an LC node 510 of the resonant circuit 506 may be
referred to as the tank voltage.
[0053] The wireless transmitter 500 may be used by a charging
device to determine if a compatible device has been placed on a
charging surface. For example, the charging device may determine
that a compatible device has been placed on the charging surface by
sending an intermittent test signal (active ping or digital ping)
through the wireless transmitter 500, where the resonant circuit
506 may detect or receive encoded signals when a compatible device
responds to the test signal or modifies a characteristic of the
test signal. In some examples, the charging device may be
configured to activate one or more coils in at least one charging
cell after receiving a response signal defined by standard,
convention, manufacturer or application. In some examples, the
compatible device can respond to a ping by communicating received
signal strength such that the charging device can find an optimal
charging cell to be used for charging the compatible device.
[0054] Passive ping techniques may use the voltage or current
measured or observed at the LC node 510 to identify the presence of
a receiving coil in proximity to the charging pad of a device
adapted in accordance with certain aspects disclosed herein. In
many conventional wireless charger transmitters, circuits are
provided to measure voltage at the LC node 510 or to measure the
current in the LC network. These voltages and currents may be
monitored for power regulation purposes or to support communication
between devices. In the example illustrated in FIG. 5, voltage at
the LC node 510 is monitored, although it is contemplated that
current may additionally or alternatively be monitored to support
passive ping in which a short pulse is provided to the resonant
circuit 506. A response of the resonant circuit 506 to a passive
ping (initial voltage V0) may be represented by the voltage (VLC)
at the LC node 510, such that:
V L C = V 0 e - ( .omega. 2 Q ) t ( Eq . 3 ) ##EQU00003##
[0055] According to certain aspects disclosed herein, coils in one
or more charging cells may be selectively activated to provide an
optimal electromagnetic field for charging a compatible device. A
charging configuration may define charging cells or charging coils
selected for use in charging a discovered chargeable device and may
define amplitude, relative phase shifts and polarity of charging
currents to be provided to the selected charging cells or charging
coils. In some instances, one or more charging coils may be
assigned to each charging cell, and some charging cells may overlap
other charging cells. In the latter instances, the optimal charging
configuration may be selected at the charging cell level. In other
instances, charging cells may be defined based on placement of a
device to be charged on a surface of the charging device. In these
other instances, the combination of coils activated for each
charging event can vary. In some implementations, a charging device
may include a driver circuit that can select one or more cells
and/or one or more predefined charging cells for activation during
a charging event.
[0056] FIG. 6 illustrates a first example in which a response 600
to a passive ping decays according to Equation 3. After the
excitation pulse at time t=0, the voltage and/or current is seen to
oscillate at the resonant frequency defined by Equation 1, and with
a decay rate defined by Equation 3. The first cycle of oscillation
begins at voltage level V.sub.0 and V.sub.LC continues to decay to
zero as controlled by the Q factor and .omega.. The example
illustrated in FIG. 6 represents a typical open or unloaded
response when no object is present or proximate to the charging
pad. In FIG. 6 the value of the Q factor is assumed to be 20.
[0057] FIG. 7 illustrates a second example in which a response 700
to a passive ping decays according to Equation 3. After the
excitation pulse at time=0, the voltage and/or current is seen to
oscillate at the resonant frequency defined by Equation 1, and with
a decay rate defined by Equation 3. The first cycle of oscillation
begins at voltage level V.sub.0 and V.sub.LC continues to decay to
zero as controlled by the Q factor and w. The example illustrated
in FIG. 7 represents a loaded response when an object is present or
proximate to the charging pad loads the coil. In FIG. 6 the Q
factor may have a value of 7. V.sub.LC oscillates at a higher
frequency in the response 700 with respect to the response 600.
[0058] FIG. 8 illustrates a set of examples in which differences in
responses 800, 820, 840 may be observed. A passive ping is
initiated when a driver circuit 504 excites the resonant circuit
506 using a pulse that is shorter than 2.5 .mu.s. Different types
of wireless receivers and foreign objects placed on the transmitter
result in different responses observable in the voltage at the LC
node 510 or current in the resonant circuit 506 of the transmitter.
The differences may indicate variations in the Q factor of the
resonant circuit 506 frequency of the oscillation of V.sub.0. Table
2 illustrates certain examples of objects placed on the charging
pad in relation to an open state.
TABLE-US-00002 TABLE 2 V.sub.peak 50% Decay Q Object Frequency (mV)
Cycles Factor None present 96.98 kHz 134 mV 4.5 20.385 Type-1
Receiver 64.39 kHz 82 mV 3.5 15.855 Type-2 Receiver 78.14 kHz 78 mV
3.5 15.855 Type-3 Receiver 76.38 kHz 122 mV 3.2 14.496 Misaligned
Type-3 210.40 kHz 110 mV 2.0 9.060 Receiver Ferrous object 93.80
kHz 110 mV 2.0 9.060 Non-ferrous object 100.30 kHz 102 mV 1.5
6.795
[0059] In Table 2, the Q factor may be calculated as follows:
Q = .pi. N ln ( 2 ) .apprxeq. 4 . 5 3 N , ( Eq . 3 )
##EQU00004##
[0060] where N is the number of cycles from excitation until
amplitude falls below 0.5 V.sub.0.
Selectively Activating Coils
[0061] According to certain aspects disclosed herein, transmitting
coils in one or more charging cells may be selectively activated to
provide an optimal electromagnetic field for charging a compatible
device. In some instances, transmitting coils may be assigned to
charging cells, and some charging cells may overlap other charging
cells. In the latter instances, the optimal charging configuration
may be selected at the charging cell level. In other instances,
charging cells may be defined based on placement of a device to be
charged on a charging surface. In these other instances, the
combination of coils activated for each charging event can vary. In
some implementations, a charging device may include a driver
circuit that can select one or more cells and/or one or more
predefined charging cells for activation during a charging
event.
[0062] FIG. 9 is a flowchart 900 that illustrates a power transfer
management procedure involving multiple sensing and/or
interrogation techniques that may be employed by a wireless
charging device implemented in accordance with certain aspects
disclosed herein. The procedure may be initiated periodically and,
in some instances, may be initiated after the wireless charging
device exits a low-power or sleep state. In one example, the
procedure may be repeated at a frequency calculated to provide
sub-second response to placement of a device on a charging pad. The
procedure may be re-entered when an error condition has been
detected during a first execution of the procedure, and/or after
charging of a device placed on the charging pad has been
completed.
[0063] At block 902, a controller may perform an initial search
using capacitive proximity sensing. Capacitive proximity sensing
may be performed quickly and with low power dissipation. In one
example, capacitive proximity sensing may be performed iteratively,
where one or more transmission coils is tested in each iteration.
The number of transmission coils tested in each iteration may be
determined by the number of sensing circuits available to the
controller. At block 904, the controller may determine whether
capacitive proximity sensing has detected the presence or potential
presence of an object proximate to one of the transmission coils.
If no object is detected by capacitive proximity sensing, the
controller may cause the charging device to enter a low-power, idle
and/or sleep state at block 924. If an object has been detected,
the controller may initiate passive ping sensing at block 906.
[0064] At block 906, the controller may initiate passive ping
sensing to either detect (in the case where capacitive sensing is
not used) or to confirm the presence of (in the case where
capacitive sensing is not used) an object near one or more (N)
transmission coils, and/or to evaluate the nature of the
proximately located object. Passive ping sensing may consume a
similar quantity of power but span a greater of time than
capacitive proximity sensing. In one example, each passive ping can
be completed in approximately 100 .mu.s and may expend 0.25 .mu.J.
A passive ping may be provided to each transmission coil identified
as being of interest by capacitive proximity sensing. In some
implementations, a passive ping may be provided to a grouping of
transmission coils located near each transmission coil identified
as being of-interest by capacitive proximity sensing, and the
grouping may include overlaid transmission coils. At block 908, the
controller may determine whether passive ping sensing has detected
the presence of a potentially chargeable device proximate to one of
the transmission coils where the potentially chargeable device may
include a receiving coil. If a potentially chargeable device has
been detected, the controller may initiate active digital ping
sensing at block 910. If no potential chargeable device has been
detected, passive ping sensing may continue at block 906 until all
of the coils have been tested and/or the controller terminates
passive ping sensing. If no potential chargeable device has been
detected, passive ping sensing may continue at block 1306 to test a
next coil in the N number of coils. Passive ping sensing continues
until all N coils are tested as illustrated by decision block 1308.
In one example, the controller terminates passive ping sensing
after all transmitting coils have been tested. When passive ping
sensing fails to find a potentially chargeable device, the
controller may cause the charging device to enter a low-power, idle
and/or sleep state. In some implementations, passive ping sensing
may be paused when a potentially chargeable device is detected so
that an active ping can be used to interrogate the potentially
chargeable device. Passive ping sensing may be resumed after the
results of an active ping have been obtained.
[0065] At block 910, the controller may use an active ping to
interrogate a potentially chargeable device. The active ping may be
provided to a transmitting coil identified by passive ping sensing.
In one example, a standards-defined active ping exchange can be
completed in approximately 90 ms and may expend 80 mJ. An active
ping may be provided to each transmission coil associated with a
potentially chargeable device.
[0066] At block 912, the controller may further identify and
configure a chargeable device. The active ping provided at block
910 may be configured to stimulate a chargeable device such that it
transmits a response that includes information identifying the
chargeable device. In some instances, the controller may fail to
identify or configure a potentially chargeable device detected by
passive ping, and the controller may resume a search based on
passive ping at block 906. At block 914, the controller may
determine whether a baseline charging profile or negotiated
charging profile should be used to charge an identified chargeable
device. The baseline, or default charging profile may be defined by
standards. In one example, the baseline profile limits charging
power to 5 W. In another example, a negotiated charging profile may
enable charging to proceed at up to 15 W. When a baseline charging
profile is selected, the controller may begin transferring power
(charging) at block 920.
[0067] At block 916, the controller may initiate a
standards-defined negotiation and calibration process that can
optimize power transfer. The controller may negotiate with the
chargeable device to determine an extended power profile that is
different from a power profile defined for the baseline charging
profile. The controller may determine at block 918 that the
negotiation and calibration process has failed and may terminate
the power transfer management procedure. When the controller
determines at block 918 that the negotiation and calibration
process has succeeded, charging in accordance with the negotiate
profile may commence at block 920.
[0068] At block 922, the controller may determine whether charging
has been successfully completed. In some instances, an error may be
detected when a negotiated profile is used to control power
transfer. In the latter instance, the controller may attempt to
renegotiate and/or reconfigure the profile at block 916. The
controller may terminate the power transfer management procedure
when charging has been successfully completed.
[0069] In some examples, the initial search using capacitive
proximity sensing or the passive ping sensing may be bypassed or
omitted from the power transfer management procedure illustrated in
FIG. 9. In some examples, other sensing techniques may be used to
sense the presence of an object or chargeable device. Other
techniques may involve the use of sensors, for example.
[0070] According to certain aspects disclosed herein, coils in one
or more charging cells may be selectively activated to provide an
optimal electromagnetic field for charging a compatible device. In
some instances, coils may be assigned to charging cells, and some
charging cells may overlap other charging cells. In the latter
instances, the optimal charging configuration may be selected at
the charging cell level. In other instances, charging cells may be
defined based on placement of a device to be charged on a charging
surface of a wireless charging device. In these other instances,
the combination of coils activated for each charging event can
vary. In some implementations, a charging device may include a
driver circuit that can select one or more cells and/or one or more
predefined charging cells for activation during a charging
event.
[0071] FIG. 10 illustrates a topology 1000 in which each coil or
charging cell is individually and/or directly driven by a driver
circuit 1002 in accordance with certain aspects disclosed herein.
The driver circuit 1002 may be configured to select one or more
coils or charging cells 100 from a group of coils 1004 to charge a
receiving device. It will be appreciated that the concepts
disclosed here in relation to charging cells 100 may be applied to
selective activation of individual coils or stacks of coils.
Charging cells 100 that are not in use receive no current flow. A
relatively large number of charging cells 100 may be in use and a
switching matrix may be employed to drive individual coils or
groups of coils. In one example, a first switching matrix may
configure connections that define a charging cell or group of coils
to be used during a charging event and a second switching matrix
(see, e.g., FIG. 15) may be used to activate the charging cell
and/or group of selected coils. The availability of direct drive to
one or more coils may permit the charging device to concurrently
transmit a ping through different groupings of coils.
[0072] FIG. 11 illustrates possible configurations 1100, 1120,
1130, 1140 of a charging surface and chargeable device 1102 that
may determine the combination of charging coils activated for a
charging event. In the illustrated example, the chargeable device
1102 has an area that is of similar magnitude to charging coils (or
charging cells) of a charging surface. In the first and second
configurations 1100, 1120, the chargeable device 1102 is larger
than a single charging coil 1104. Based on the geometry and
arrangement of the charging coils 1104, 1106, 1108, 1110 the
chargeable device 1102 can physically cover adjacent charging
coils. In the third configuration 1130 and fourth configuration
1140, for example, the chargeable device 1102 has been placed such
that it substantially overlaps a single charging coil 1108 and
partially covers multiple other charging coils 1104, 1106, 1110.
When the chargeable device 1102 has established its presence over a
charging coil 1108 and is receiving power from the charging coil
1108, the adjacent charging coils 1104, 1106, 1110 may be unusable
for charging other devices due to the interference in
electromagnetic flux. In some instances, configuration information
transmitted to a first charging cell by a first chargeable device
through modulation of the electromagnetic flux may be received by a
second charging cell and misinterpreted as configuration
information for a second chargeable device. In the latter example,
inefficient power transfer may occur when the second chargeable
device is incapable of handling power levels requested by the first
chargeable device.
[0073] Certain aspects of this disclosure can prevent adjacent
charging coils 1104, 1106, 1110 from interfering with the
chargeable device 1102 during charging. In some examples, the
adjacent charging coils 1104, 1106, 1110 may be marked or
considered unusable for charging other devices. In some examples,
the adjacent charging coils 1104, 1106, 1110 may be blocked from
participating in device discovery procedures. In one example, the
adjacent charging coils 1104, 1106, 1110 may be excluded from
differential capacitive sensing, passive ping and/or active ping
procedures. In another example, negative results may be
preconfigured for the adjacent charging coils 1104, 1106, 1110 when
initiating differential capacitive sensing, passive ping and/or
active ping procedures. Result pre-configuration and/or blocking of
adjacent charging coils 1104, 1106, 1110 from discovery procedures
can prevent the inclusion of the adjacent charging coils 1104,
1106, 1110 in active charging cells of a charging
configuration.
[0074] In one aspect of the disclosure, the adjacent charging coils
1104, 1106, 1110 can be excluded from an active ping discovery
procedure. During active ping discovery, the charging system may
ping or scan all coils in a predefined, preconfigured parallel,
sequential, pseudorandom or random sequence in an attempt to detect
a chargeable device 1102. In an initial configuration 1130, all
charging coils in the charging surface may be available to be used
for charging. In the fourth configuration 1140, presence of the
chargeable device 1102 has been established and the chargeable
device 1102 is being charged by an optimally positioned charging
coil 1108. In the fourth configuration 1140, the unusable adjacent
charging coils 1104, 1106, 1110 are blocked until the optimally
positioned charging coil 1108 has been released from its charging
contract with the chargeable device 1102.
[0075] In accordance with certain aspects of this disclosure, any
number of charging coils can be blocked around the chargeable
device. FIG. 12 illustrates configurations 1200, 1220 of a
chargeable device 1202, 1222 on a surface of a wireless charging
device in which certain coils are unusable or blocked for discovery
purposes when the chargeable device 1202, 1222 is being charged.
The number and location of unusable charging coils may be defined
by a charging configuration for the chargeable device 1202, 1222
and may vary based on the type of a charging coil 1210, 1228 that
is optimally positioned or selected for charging the chargeable
device 1202, 1222, the charging contract or configuration
negotiated between the wireless charging device and the chargeable
device 1202, 1222, and the topology or configuration of the surface
of the wireless charging device. In the first configuration 1200,
two concentric rings of charging coils 1206, 1208 adjacent to an
active charging coil 1210 are blocked or disabled. A concentric
ring of charging coils may include charging coils that are on or
within a circle that is concentric with the active charging coil
1210. The number of blocked or disabled concentric rings of
charging coils 1204 may be selected based on the maximum charging
power, configured charging power or contracted charging power that
may be transmitted through the active charging coil 1210 or
potentially through another charging coil 1204, or for other
reasons. For example, a larger number of concentric rings of
charging coils may be blocked when the wireless charging device has
many smaller charging coils than when the wireless charging device
has fewer larger coils.
[0076] In the second configuration 1220, the wireless charging
device employs sensing techniques that can detect the edges of the
chargeable device 1222 on a charging surface. In another example,
the outline of the chargeable device 1222 can be detected using
capacitive sense, inductive sense, pressure, Q-factor measurement
or any other suitable device locating technology. In the
illustrated example, the chargeable device 1222 has an elongated
shape and the number of concentric circles of blocked charging
coils may be selected based on inefficient tradeoffs when edge
detection is unavailable or unused. For example, tradeoffs may be
made to provide adequate protection for larger devices, devices
with asymmetric outlines and smaller devices. In accordance with
certain aspects of the disclosure, edge detection can enable
blocking of charging coils 1226 adjacent to the outline or
footprint of the chargeable device 1222 when the active coil 1228
is located substantially in the center of the outline of the
chargeable device 1222. The footprint of the chargeable device 1222
may refer to the projected coverage of the charging surface by the
chargeable device 1222, while the outline of the chargeable device
1222 may be defined by physical edges of the chargeable device 1222
when laid flat on the charging surface. Charging coils 1224, 1230
immediately adjacent to the chargeable device 1222 can be blocked
regardless of distance from the active coil 1228. In the latter
example, the use of edge sensing techniques can protect the
chargeable device 1222 from interference when the chargeable device
1222 has an asymmetric outline that may not be optimally protected
by locking a fixed number of concentric rings of adjacent charging
coils.
[0077] In certain implementations, a chargeable device may receive
power from two or more active coils. In one example, the chargeable
device may have a relatively large footprint with respect to the
charging surface and may have multiple receiving coils that can
engage multiple charging coils to receive power. In another
example, a receiving coil of the chargeable device may be placed
substantially equidistant from two or more charging coils and a
charging configuration may be defined whereby two or more adjacent
charging coils in the charging surface provide power to the
chargeable device. In these examples, an exclusion zone may be
defined around the active coils such that charging coils within or
impinging on the exclusion zone device can be blocked.
[0078] The use of restricted device discovery and charging activity
blocking on adjacent charging coils or charging coils that are
known to be under a chargeable device 1102, 1202, 1222 can reduce
power draw since only the charging coils that are outside the
footprint of a chargeable device can use and/or dissipate power
during charging and/or discovery. A reduced electromagnetic
signature may be obtained. For example, electromagnetic radiation
can be reduced when fewer charging coils are involved in device
discovery. In some instances, the reduction in electromagnetic
signature can enable the charging device to more easily satisfy
regulatory standards such as Federal Communications Commission
(FCC) and Conformite Europeenne (European Conformity or CE)
standards.
[0079] FIG. 13 is flowchart 1300 illustrating one example of a
method for operating a charging device. The method may be performed
by a controller provided in a wireless charging apparatus. At block
1302, the controller may determine that a chargeable device is
positioned proximate to a charging coil provided by a charging
surface. At block 1304, the controller may provide a charging
current to the charging coil. At block 1306, the controller may
exclude a plurality of adjacent coils from operation while the
current is provided to the charging coil. Each of the adjacent
coils may be located within the charging surface neighboring to the
charging coil.
[0080] In some implementations, the controller may exclude the
plurality of adjacent coils from participating in one or more types
of device discovery procedures. The one or more types of device
discovery procedures may include a discovery procedure involving
differential capacitive sense. The one or more types of device
discovery procedures may include a passive ping discovery
procedure. The one or more device types of discovery procedures may
include an active ping discovery procedure.
[0081] The controller may exclude the plurality of adjacent coils
from operation by refraining from providing charging current to the
plurality of adjacent coils while the current is provided to the
charging coil. The controller may exclude the plurality of adjacent
coils from operation by blocking wireless communication through the
plurality of adjacent coils while the current is provided to the
charging coil. The plurality of adjacent coils include coils may be
located on or within a circle that is concentric with the charging
coil. The plurality of adjacent coils may be arranged around a
footprint of the chargeable device on the charging surface.
[0082] In some instances, the controller may determine that the
chargeable device is positioned proximate to the charging coil by
detecting the chargeable device during a device discovery procedure
that includes differential capacitive sense, passive ping or active
ping.
Example of a Processing Circuit
[0083] FIG. 14 is a diagram illustrating an example of a hardware
implementation for an apparatus 1400 that may be incorporated in a
charging device or in a receiving device that enables a battery to
be wirelessly charged. In some examples, the apparatus 1400 may
perform one or more functions disclosed herein. In accordance with
various aspects of the disclosure, an element, or any portion of an
element, or any combination of elements as disclosed herein may be
implemented using a processing circuit 1402. The processing circuit
1402 may include one or more processors 1404 that are controlled by
some combination of hardware and software modules. Examples of
processors 1404 include microprocessors, microcontrollers, digital
signal processors (DSPs), SoCs, ASICs, field programmable gate
arrays (FPGAs), programmable logic devices (PLDs), state machines,
sequencers, gated logic, discrete hardware circuits, and other
suitable hardware configured to perform the various functionality
described throughout this disclosure. The one or more processors
1404 may include specialized processors that perform specific
functions, and that may be configured, augmented or controlled by
one of the software modules 1416. The one or more processors 1404
may be configured through a combination of software modules 1416
loaded during initialization, and further configured by loading or
unloading one or more software modules 1416 during operation.
[0084] In the illustrated example, the processing circuit 1402 may
be implemented with a bus architecture, represented generally by
the bus 1410. The bus 1410 may include any number of
interconnecting buses and bridges depending on the specific
application of the processing circuit 1402 and the overall design
constraints. The bus 1410 links together various circuits including
the one or more processors 1404, and storage 1406. Storage 1406 may
include memory devices and mass storage devices and may be referred
to herein as computer-readable media and/or processor-readable
media. The storage 1406 may include transitory storage media and/or
non-transitory storage media.
[0085] The bus 1410 may also link various other circuits such as
timing sources, timers, peripherals, voltage regulators, and power
management circuits. A bus interface 1408 may provide an interface
between the bus 1410 and one or more transceivers 1412. In one
example, a transceiver 1412 may be provided to enable the apparatus
1400 to communicate with a charging or receiving device in
accordance with a standards-defined protocol. Depending upon the
nature of the apparatus 1400, a user interface 1418 (e.g., keypad,
display, speaker, microphone, joystick) may also be provided, and
may be communicatively coupled to the bus 1410 directly or through
the bus interface 1408.
[0086] A processor 1404 may be responsible for managing the bus
1410 and for general processing that may include the execution of
software stored in a computer-readable medium that may include the
storage 1406. In this respect, the processing circuit 1402,
including the processor 1404, may be used to implement any of the
methods, functions and techniques disclosed herein. The storage
1406 may be used for storing data that is manipulated by the
processor 1404 when executing software, and the software may be
configured to implement any one of the methods disclosed
herein.
[0087] One or more processors 1404 in the processing circuit 1402
may execute software. Software shall be construed broadly to mean
instructions, instruction sets, code, code segments, program code,
programs, subprograms, software modules, applications, software
applications, software packages, routines, subroutines, objects,
executables, threads of execution, procedures, functions,
algorithms, etc., whether referred to as software, firmware,
middleware, microcode, hardware description language, or otherwise.
The software may reside in computer-readable form in the storage
1406 or in an external computer-readable medium. The external
computer-readable medium and/or storage 1406 may include a
non-transitory computer-readable medium. A non-transitory
computer-readable medium includes, by way of example, a magnetic
storage device (e.g., hard disk, floppy disk, magnetic strip), an
optical disk (e.g., a compact disc (CD) or a digital versatile disc
(DVD)), a smart card, a flash memory device (e.g., a "flash drive,"
a card, a stick, or a key drive), RAM, ROM, a programmable
read-only memory (PROM), an erasable PROM (EPROM) including EEPROM,
a register, a removable disk, and any other suitable medium for
storing software and/or instructions that may be accessed and read
by a computer. The computer-readable medium and/or storage 1406 may
also include, by way of example, a carrier wave, a transmission
line, and any other suitable medium for transmitting software
and/or instructions that may be accessed and read by a computer.
Computer-readable medium and/or the storage 1406 may reside in the
processing circuit 1402, in the processor 1404, external to the
processing circuit 1402, or be distributed across multiple entities
including the processing circuit 1402. The computer-readable medium
and/or storage 1406 may be embodied in a computer program product.
By way of example, a computer program product may include a
computer-readable medium in packaging materials. Those skilled in
the art will recognize how best to implement the described
functionality presented throughout this disclosure depending on the
particular application and the overall design constraints imposed
on the overall system.
[0088] The storage 1406 may maintain software maintained and/or
organized in loadable code segments, modules, applications,
programs, etc., which may be referred to herein as software modules
1416. Each of the software modules 1416 may include instructions
and data that, when installed or loaded on the processing circuit
1402 and executed by the one or more processors 1404, contribute to
a run-time image 1414 that controls the operation of the one or
more processors 1404. When executed, certain instructions may cause
the processing circuit 1402 to perform functions in accordance with
certain methods, algorithms and processes described herein.
[0089] Some of the software modules 1416 may be loaded during
initialization of the processing circuit 1402, and these software
modules 1416 may configure the processing circuit 1402 to enable
performance of the various functions disclosed herein. For example,
some software modules 1416 may configure internal devices and/or
logic circuits 1422 of the processor 1404 and may manage access to
external devices such as a transceiver 1412, the bus interface
1408, the user interface 1418, timers, mathematical coprocessors,
and so on. The software modules 1416 may include a control program
and/or an operating system that interacts with interrupt handlers
and device drivers, and that controls access to various resources
provided by the processing circuit 1402. The resources may include
memory, processing time, access to a transceiver 1412, the user
interface 1418, and so on.
[0090] One or more processors 1404 of the processing circuit 1402
may be multifunctional, whereby some of the software modules 1416
are loaded and configured to perform different functions or
different instances of the same function. The one or more
processors 1404 may additionally be adapted to manage background
tasks initiated in response to inputs from the user interface 1418,
the transceiver 1412, and device drivers, for example. To support
the performance of multiple functions, the one or more processors
1404 may be configured to provide a multitasking environment,
whereby each of a plurality of functions is implemented as a set of
tasks serviced by the one or more processors 1404 as needed or
desired. In one example, the multitasking environment may be
implemented using a timesharing program 1420 that passes control of
a processor 1404 between different tasks, whereby each task returns
control of the one or more processors 1404 to the timesharing
program 1420 upon completion of any outstanding operations and/or
in response to an input such as an interrupt. When a task has
control of the one or more processors 1404, the processing circuit
is effectively specialized for the purposes addressed by the
function associated with the controlling task. The timesharing
program 1420 may include an operating system, a main loop that
transfers control on a round-robin basis, a function that allocates
control of the one or more processors 1404 in accordance with a
prioritization of the functions, and/or an interrupt driven main
loop that responds to external events by providing control of the
one or more processors 1404 to a handling function.
[0091] In one implementation, the apparatus 1400 includes or
operates as a wireless charging apparatus that has a battery
charging power source coupled to a charging circuit, a plurality of
charging cells and a controller, which may be included in one or
more processors 1404. The plurality of charging cells may be
configured to provide a charging surface. At least one coil may be
configured to direct an electromagnetic field through a charge
transfer area of each charging cell.
[0092] The controller may be configured to manage or perform a
passive ping procedure by providing a pulse to the charging
circuit, detecting a frequency of oscillation of the charging
circuit responsive to the pulse or a rate of decay of the
oscillation of the charging circuit, and determining that a
chargeable device has been placed in proximity to a coil of the
charging circuit based on changes in a characteristic of the
charging circuit. The pulse may have a duration that is less than
half the period of a nominal resonant frequency of the charging
circuit. In some instances, the pulse has a duration that is
multiple periods of the nominal resonant frequency of the charging
circuit. In one example, the change in the characteristic of the
charging circuit causes a change in rate of decay of the
oscillation of the charging circuit. In one example, the change in
the characteristic of the charging circuit causes a change in the
frequency of oscillation of the charging circuit to vary with
respect to the resonant frequency of the charging circuit.
[0093] In certain examples, the controller is configured to
determine that a chargeable device is positioned proximate to a
charging coil provided by a charging surface, provide a charging
current to the charging coil, and exclude a plurality of adjacent
coils from operation while the current is provided to the charging
coil. Each of the adjacent coils may be located within the charging
surface adjacent to the charging coil.
[0094] In some implementations, the controller may exclude the
plurality of adjacent coils from participating in one or more
device discovery procedures. The one or more device discovery
procedures may include a discovery procedure involving differential
capacitive sense. The one or more device discovery procedures may
include a passive ping discovery procedure. The one or more device
discovery procedures may include an active ping discovery
procedure.
[0095] The controller may exclude the plurality of adjacent coils
from operation by refraining from providing charging current to the
plurality of adjacent coils while the current is provided to the
charging coil. The controller may exclude the plurality of adjacent
coils from operation by blocking wireless communication through the
plurality of adjacent coils while the current is provided to the
charging coil. The plurality of adjacent coils include coils may be
located on or within a circle that is concentric with the charging
coil. The plurality of adjacent coils may be arranged around a
footprint of the chargeable device on the charging surface.
[0096] In some instances, the controller may determine that the
chargeable device is positioned proximate to the charging coil by
detecting the chargeable device during a device discovery procedure
that includes differential capacitive sense, passive ping or active
ping.
[0097] In some implementations, the storage 1406 maintains
instructions and information where the instructions are configured
to cause the one or more processors 1404 to determine that a
chargeable device is positioned proximate to a charging coil
provided by a charging surface, provide a charging current to the
charging coil, and exclude a plurality of adjacent coils from
operation while the current is provided to the charging coil. Each
of the adjacent coils may be located within the charging surface
adjacent to the charging coil.
[0098] In some implementations, the instructions are configured to
cause the one or more processors 1404 to exclude the plurality of
adjacent coils from participating in one or more device discovery
procedures. The one or more device discovery procedures may include
a discovery procedure involving differential capacitive sense. The
one or more device discovery procedures may include a passive ping
discovery procedure. The one or more device discovery procedures
may include an active ping discovery procedure.
[0099] The instructions are configured to cause the one or more
processors 1404 to exclude the plurality of adjacent coils from
operation by refraining from providing charging current to the
plurality of adjacent coils while the current is provided to the
charging coil. The controller may exclude the plurality of adjacent
coils from operation by blocking wireless communication through the
plurality of adjacent coils while the current is provided to the
charging coil. The plurality of adjacent coils include coils may be
located on or within a circle that is concentric with the charging
coil. The plurality of adjacent coils may be arranged around a
footprint of the chargeable device on the charging surface.
[0100] In some instances, instructions are configured to cause the
one or more processors 1404 to determine that the chargeable device
is positioned proximate to the charging coil by detecting the
chargeable device during a device discovery procedure that includes
differential capacitive sense, passive ping or active ping.
[0101] The previous description is provided to enable any person
skilled in the art to practice the various aspects described
herein. Various modifications to these aspects will be readily
apparent to those skilled in the art, and the generic principles
defined herein may be applied to other aspects. Thus, the claims
are not intended to be limited to the aspects shown herein, but is
to be accorded the full scope consistent with the language claims,
wherein reference to an element in the singular is not intended to
mean "one and only one" unless specifically so stated, but rather
"one or more." Unless specifically stated otherwise, the term
"some" refers to one or more. All structural and functional
equivalents to the elements of the various aspects described
throughout this disclosure that are known or later come to be known
to those of ordinary skill in the art are expressly incorporated
herein by reference and are intended to be encompassed by the
claims. Moreover, nothing disclosed herein is intended to be
dedicated to the public regardless of whether such disclosure is
explicitly recited in the claims. No claim element is to be
construed under the provisions of 35 U.S.C. .sctn. 112, sixth
paragraph, unless the element is expressly recited using the phrase
"means for" or, in the case of a method claim, the element is
recited using the phrase "step for."
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