U.S. patent application number 16/030493 was filed with the patent office on 2018-11-15 for methods for forming shield materials onto inductive coils.
This patent application is currently assigned to Apple Inc.. The applicant listed for this patent is Apple Inc.. Invention is credited to Makiko K. Brzezinski, Christopher S. Graham, Eric S. Jol.
Application Number | 20180330867 16/030493 |
Document ID | / |
Family ID | 54870270 |
Filed Date | 2018-11-15 |
United States Patent
Application |
20180330867 |
Kind Code |
A1 |
Graham; Christopher S. ; et
al. |
November 15, 2018 |
METHODS FOR FORMING SHIELD MATERIALS ONTO INDUCTIVE COILS
Abstract
Methods of and systems for directing flux from a transmit coil
to a receive coil within an inductive power transfer system are
disclosed. For example, a transmit coil may be shielded with a
contoured shield made from a ferromagnetic material. The contoured
shield may contour to several surfaces of the transmit coil so as
to define a single plane through which flux may be directed to a
receive coil.
Inventors: |
Graham; Christopher S.; (San
Francisco, CA) ; Jol; Eric S.; (San Jose, CA)
; Brzezinski; Makiko K.; (Santa Clara, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
|
|
Assignee: |
Apple Inc.
Cupertino
CA
|
Family ID: |
54870270 |
Appl. No.: |
16/030493 |
Filed: |
July 9, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15269925 |
Sep 19, 2016 |
10043612 |
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16030493 |
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14310694 |
Jun 20, 2014 |
9460846 |
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15269925 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 7/0042 20130101;
H02J 50/10 20160201; Y10T 29/49021 20150115; H01F 1/147 20130101;
H02J 7/025 20130101; H01F 27/288 20130101; H02J 50/70 20160201;
H01F 27/36 20130101; H01F 27/02 20130101; H02J 7/0044 20130101;
H01F 38/14 20130101; H01F 27/28 20130101 |
International
Class: |
H01F 27/28 20060101
H01F027/28; H02J 7/00 20060101 H02J007/00; H02J 7/02 20060101
H02J007/02; H02J 50/70 20060101 H02J050/70; H01F 27/36 20060101
H01F027/36; H01F 38/14 20060101 H01F038/14; H01F 27/02 20060101
H01F027/02; H02J 50/10 20060101 H02J050/10; H01F 1/147 20060101
H01F001/147 |
Claims
1. A shield for an annular coil comprising: a first portion
contoured over a surface of the annular coil such that the first
portion fills within at least a portion of void spaces defined
between stacked coils positioned along the surface of the annular
coil.
2. The shield of claim 1 wherein the shield is made from soft
magnetic material.
3. The shield of claim 2 wherein the shield is made from at least
one of iron, iron silicates, iron-cobalt, manganese-zinc, nickel,
or nickel-zinc.
4. The shield of claim 1 wherein the shield is made from a doped
material selected from plastic, glass, or composite material.
5. The shield of claim 4 wherein the doped material comprises a
dopant made from a metal powder.
6. The shield of claim 1 further comprising a second portion and a
third portion coupled to the first and second portions.
7. The shield of claim 1 further comprising an adhesive layer
disposed between the shield and the annular coil.
8. The shield of claim 7 wherein the adhesive layer comprises a
heat activated film.
9. The shield of claim 7 wherein the adhesive is made from a doped
material comprising a dopant made from a metal powder.
10. The shield of claim 1 wherein: the annular coil comprises a
plurality of windings of an electrical conductor defining an
interior coil sidewall, an exterior coil sidewall and a back
surface extending between the interior and exterior coil sidewalls;
the first portion is contoured to either the interior or exterior
sidewall; and the second portion comprises a ring contoured to the
back surface.
11. The shield of claim 1 wherein the annular coil is contained
within a first housing.
12. A shield for an annular coil comprising: a first portion
comprising a plurality of individual petals, wherein the first
portion is contoured over a surface of the annular coil such that
the first portion fills within at least a portion of void spaces
defined between stacked coils positioned along the surface of the
annular coil.
13. The shield of claim 12 further comprising a filler material
disposed between adjacent individual petals of the plurality of
individual petals.
14. The shield of claim 12 further comprising a second portion and
a third portion coupled to the first portion, wherein the second
portion is disposed between the first and third portions.
15. The shield of claim 14 wherein the third portion comprises a
plurality of individual petals positioned across the second portion
from the plurality of individual petals of the first portion.
16. The shield of claim 14 further comprising a filler material
disposed between adjacent individual petals of the plurality of
individual petals.
17. An inductive charging system comprising: an electronic device
comprising: an annular receive coil; and a shield contoured over a
surface of the receive coil such that the shield fills within at
least a portion of void spaces defined between stacked coils
positioned along the surface of the receive coil.
18. The inductive charging system of claim 17 wherein the shield
defines a receiving area of the receive coil for concentrating
magnetic flux therethrough.
19. The inductive charging system of claim 18 wherein the shield is
a first shield, and the inductive charging system further
comprises: an inductive charging device comprising: a housing
comprising an interface surface for receiving the electronic
device; a transmitter coil within the housing and positioned below
the interface surface; and a second shield contoured over at least
two surfaces of the transmit coil defining a transmitter area of
the receive coil for concentrating magnetic flux therefrom;
wherein: the transmitting area is oriented to face the interface
surface.
20. The inductive charging system of claim 19 wherein the
electronic device is received on the interface surface, the
receiving area is oriented to face the transmitting area.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/269,925, filed Sep. 19, 2016, which is a
continuation of U.S. patent application Ser. No. 14/310,694, filed
on Jun. 20, 2014, the disclosure of which is herein incorporated by
reference in its entirety for all purposes.
TECHNICAL FIELD
[0002] Embodiments described herein relate to electromagnetic power
transfer systems, and in particular to systems and methods for
shielding electromagnetic coils for improved inductive power
transfer.
BACKGROUND
[0003] Portable electronic devices may include one or more
batteries that may require recharging from time to time. Such
devices may include electric vehicles, cell phones, smart phones,
tablet computers, laptop computers, wearable devices, navigation
devices, sports devices, health analysis devices, medical data
devices, location tracking devices, accessory devices, home
appliances, peripheral input devices, remote control devices, and
so on.
[0004] Some batteries may recharge wirelessly by accepting
inductive power provided by an inductive power transmitter. For
instance, a battery-powered electronic device configured to accept
inductive power may be placed nearby a transmitter adapted to
produce inductive power. In these systems, a transmitting coil
within the transmitter may produce a time-varying magnetic flux
that may induce a current within a receiving coil within the
electronic device. The received current may be used by the
electronic device to replenish the charge of a rechargeable
battery.
[0005] In many examples, the inductive power transmitter may
transmit more power than is received by the inductive power
receiver. In other words, a portion of the magnetic flux produced
by transmitter may not pass through the receiving coil, but instead
may pass through and disturb other components within the
transmitter and/or receiver. This wasted power is often dissipated
as undesirable heat.
[0006] Accordingly, there may be a present need for an improved
method of directing flux from a transmit coil to a receive coil
within an inductive power transfer system.
SUMMARY
[0007] Embodiments described herein may relate to, include, or take
the form of a shield for an annular coil including at least an
outer portion contoured to an outer sidewall of the annular coil,
an inner portion contoured to an inner sidewall of the annular
coil, and a top portion contoured to a top portion of the annular
coil, wherein the top portion couples the inner portion to the
outer portion.
[0008] Other embodiments may include a configuration in which the
shield may be made from soft magnetic material. For example, the
shield may be iron, iron silicate, iron-cobalt, manganese-zinc,
nickel, or nickel-zinc. In further examples, the material selected
for the shield may have a relatively high magnetic permeability. In
other examples, the shield may be made from a doped material
selected such as plastic, glass, or any other composite material.
The dopant used may be a metal powder.
[0009] Certain embodiments may include a configuration in which the
outer portion and inner portion of the shield are defined by a
plurality of individual petals that are folded from the top portion
of the shield. I n these configurations, a filler material can be
disposed between individual petals.
[0010] Further embodiments may also include an adhesive layer
disposed between the shield and the annular coil. The adhesive
layer may be a heat activated film and, in some examples, may also
be doped with metal powder.
[0011] Other embodiments described herein may relate to, include,
or take the form of an inductive charging system including an
electronic device having a rechargeable battery, a receive coil
electrically associated with the battery, and a first shield
contoured over at least two surfaces of the receive coil defining a
receiving area of the receive coil for concentrating magnetic flux
therethrough. Many examples also include an inductive charging
device including a housing with an interface surface for receiving
the electronic device, a transmit coil within the housing and
positioned below the interface surface, and a second shield
contoured over at least two surfaces of the transmit coil defining
a transmitting area of the receive coil for concentrating magnetic
flux therefrom, wherein the transmitting area may be oriented to
face the interface surface. In many examples, when the electronic
device is positioned on the interface surface, the receiving area
may be oriented to face the transmitting area.
[0012] Embodiments described herein may relate to, include, or take
the form of a method of manufacturing a contoured shield for an
electromagnetic coil including at least the operations of forming a
shield sheet with a plurality of petals, placing the shield sheet
on a first surface of the electromagnetic coil, and folding each of
the plurality of petals to contour to the surface of the
electromagnetic coil.
[0013] Methods described herein may further include positioning a
heat activated film between the shield and the electromagnetic coil
to forma shielded coil assembly, and subsequently heating the
shielded coil assembly to activate the heat activated film.
[0014] Other embodiments may further include disposing a filler
material between adjacent petals.
[0015] Other embodiments may include press fitting the contoured
shield and electromagnetic coil assembly onto a mold having a
selected shape, for example, a conical shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Reference will now be made to representative embodiments
illustrated in the accompanying figures. It should be understood
that the following descriptions are not intended to limit the
disclosure to one preferred embodiment. To the contrary, it is
intended to cover alternatives, modifications, and equivalents as
may be included within the spirit and scope of the described
embodiments as defined by the appended claims.
[0017] FIG. 1A depicts a front perspective view of an example
inductive power transfer system in an unmated configuration.
[0018] FIG. 1B depicts a front perspective view of an example
inductive power transfer system in a mated configuration.
[0019] FIG. 1C depicts a side cross section view of the inductive
power transfer system of FIG. 1B along line 1C-1C.
[0020] FIG. 2A depicts a top perspective view of an example
unshielded electromagnetic coil.
[0021] FIG. 2B depicts a bottom perspective view of the example
electromagnetic coil of FIG. 2A shielded on three sides.
[0022] FIG. 2C depicts a top perspective view of an example
electromagnetic coil of FIG. 2A.
[0023] FIG. 3A depicts an example side cross-section view taken
along line 3-3 of FIG. 2C showing a contoured shield at least
partially interstitially engaging an outer surface of the
electromagnetic coil.
[0024] FIG. 3B depicts an example side cross-section view taken
along line 3-3 of FIG. 2C showing a contoured shield at least
partially interstitially engaging an outer surface of the
electromagnetic coil via a heat activated film.
[0025] FIG. 3C depicts an example side cross-section of a shielded
coil showing a contoured shield at least partially interstitially
engaging an outer surface of the coil, the shield and the coil
following an arbitrary curve.
[0026] FIG. 4A depicts an example top plan view of a die cut shield
prior to forming onto an electromagnetic coil.
[0027] FIG. 4B depicts an example top plan view of a die cut and
separated shield prior to forming onto an electromagnetic coil.
[0028] FIG. 5 depicts a flow chart of example operations of a
method for applying a contoured shield to an electromagnetic
coil.
[0029] FIG. 6 depicts a flow chart of example operations of a
method for applying a contoured shield to an electromagnetic
coil.
[0030] The use of the same or similar reference numerals in
different drawings indicates similar, related, or identical
items.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Embodiments described herein may relate to, include, or take
the form of improved methods of and systems for directing flux from
a transmit coil to a receive coil within an inductive power
transfer system.
[0032] An inductive power transfer system typically includes an
inductive power-transmitting component to transmit power and an
inductive power-receiving component to receive power. An inductive
power-receiving component may be incorporated within a portable
electronic device to provide a convenient means of wirelessly
recharging one or more internal batteries. An inductive
power-transmitting component may be incorporated within a
recharging device associated with the portable electronic device.
Example portable electronic devices may include media players,
media storage devices, personal digital assistants, tablet
computers, cellular telephones, laptop computers, smart phones,
styluses, global positioning sensor units, remote control devices,
wearable devices, electric vehicles, home appliances, location
tracking devices, medical data devices, health analysis devices,
health monitoring devices, sports devices, accessory devices, and
so on. Example recharging devices may include docks, stands, clips,
plugs, mats, attachments, and so on.
[0033] In many examples, a battery-powered electronic device
("accessory") may be positioned on a power-transmitting device or
surface ("dock"). In these systems, an electromagnetic coil within
the dock ("transmit coil") may produce a time-varying
electromagnetic flux ("transmitting power") to induce a current
within an electromagnetic coil within accessory ("receive coil").
In other examples, a transmit coil may produce a static
electromagnetic field and may physically move, shift, or otherwise
change its position to produce a spatially-varying electromagnetic
flux to induce a current within the receive coil.
[0034] The accessory may use the received current to replenish the
charge of a rechargeable battery ("receiving power") or to provide
power to operating components associated with the accessory. In
other words, when the accessory is positioned on the dock, the dock
may wirelessly transmit power via the transmit coil to the receive
coil of the accessory.
[0035] However, in many examples, the dock often transmits more
power than is received by the accessory to ensure the accessory
receives the required and expected amount of power. In other words,
a portion of the magnetic flux produced by transmit coil does not
pass through, and thus does not induce current within, the receive
coil of the accessory. For example, the transmit and receive coils
are typically positioned along a shared central axis and are
oriented in parallel planes to face one another. In this
arrangement, a portion of the flux produced the transmit coil may
pass behind or beside the transmit coil, into the housing of the
dock, or into other portions of the receiver. This unused flux may
pass through and disturb other electronic components within the
transmitter and/or receiver and may be dissipated as undesirable
heat.
[0036] In many cases, heating of the accessory and/or dock may
cause damage to electronic components or housings, reduce the
operative life of either or both devices, may render the devices
unsafe to use for a period of time, or may prove inconvenient or
frustrating to a user compelled to wait for the devices to
cool.
[0037] Accordingly, embodiments described herein relate to,
include, and take the form of improved methods of directing flux
from a transmit coil to a receive coil by providing a contoured
flux-directing shield on either or both the transmit and receive
coils within an inductive power transmitting system.
[0038] Typical portable electronic devices including one or more
electromagnetic coils for inductive power transfer may include a
planar shield, such as a ferrite sheet, to protect electronic
components from flux generated by a transmit or receive coil. For
example, an inductive power transmitter may include a ferrite sheet
layer between a transmit coil and operational circuitry to protect
the circuitry from disturbance, interference, or heating resulting
from the passage of flux therethrough. In other examples, an
accessory may include a ferrite sheet layer between a receive coil
and operational circuitry to similarly protect (i.e., direct flux
away from) the operational circuitry.
[0039] Embodiments described herein relate to flux-directing
shields for electromagnetic coils that are contoured to the coil to
provide concentrated flux paths directed toward an axially aligned
receive coil. For example, as noted above, transmit and receive
coils may be positioned along a shared central axis and are
oriented in parallel planes to face one another. Embodiments
described herein contour a contoured shield around the surfaces of
the coils not facing one another such that a concentrated flux path
is defined between the front-facing surfaces of the transmit and
receive coils.
[0040] In one embodiment with an annular transmit coil having a
rectangular cross-section, the contoured shield may have three
defined surfaces. A first surface of the shield may contour to the
interior sidewall of the annular transmit coil. A second surface of
the shield may contour to the exterior sidewall of the annular
transmit coil. A third surface of the shield may contour to the
back surface of the annular transmit coil. In this manner, three of
four sides of the rectangular cross-section of the annular transit
coil may be shielded by the contoured shield. As a result of the
contoured shield, magnetic flux emanating from the interior
sidewall, exterior sidewall, and back surface of the annular
transmit coil may be absorbed by the contoured shield and
redirected to exit the shield along the front surface of the
transmit coil.
[0041] In many embodiments, the contoured shield may be made from a
ferromagnetic material such as iron or an iron alloy such as iron
cobalt, iron nickel, or steel. In further embodiments, other
materials may be used such as materials having a relatively high
magnetic permeability. In still further embodiments, the material
selected for the contoured shield may be a doped polymer. For
example, the polymer may be doped with an iron powder or an iron
alloy powder. These and other materials may be selected for the
contoured shield to provide a path of lower magnetic reluctance for
the flux produced by the coil. Accordingly, flux is directed to
emanate from the front face of the coil.
[0042] Further embodiments may include a contoured shield that is
formed to interstitially engage the area between individual coils.
For example, a transmit coil may include more than one stacks of
windings of wire having a circular cross-section. In these
embodiments, the contoured shield may be formed interstitially
within the void space defined between the stacked coils. In this
manner, the contoured shield may more tightly engage the coil,
providing a path of even lower magnetic reluctance for the flux
produced by the coil. Accordingly, flux is directed to emanate from
the front face of the coil.
[0043] The thickness of the contoured shield may vary from
embodiment to embodiment. In many examples, the thickness may be
selected, at least in part, upon the magnetic saturation point and
permeability of the material in addition to the strength of the
magnetic field to be produced by the coil. For example, in certain
embodiments, high magnetic permeability may be desirable. One may
appreciate that materials with high magnetic permeability typically
have low magnetic saturation points. In these embodiments, the
thickness of the contoured shield may depend on the maximum
magnetic field expected from the coil. In further embodiments, the
contoured shield may be composed of a composite material, such as a
layered material. Individual layers may be adapted to have
different magnetic permeability, different thickness, or may be
made from different materials.
[0044] In further embodiments, the contoured shield may be affixed
or adhered to the coil using one or more layers of adhesive. For
example, certain embodiments may include a heat activated film
adhesive disposed between the contoured shield and the coil. During
a production process, the contoured shield, film, and coil may be
heated to permanently adhere the contoured shield to the coil. In
other embodiments, the adhesive may be a curable liquid adhesive or
any other type of adhesive.
[0045] In further embodiments, the adhesive may be made from a
polymer material that may be doped with a dopant having high
magnetic permeability. For example, a heat activated film may be
doped with iron powder, an iron alloy powder, or any other high
permeability dopant. In this manner, the adhesive itself may
provide a path of low magnetic reluctance for the flux produced by
the coil.
[0046] In many embodiments, a contoured shield may also be applied
to multiple surfaces of a receive coil. In this manner, the
contoured shield may provide a low path of magnetic reluctance for
the flux produced by the transmit coil such that a greater density
of flux passes through the receive coil.
[0047] In many embodiments, the receive coil may be incorporated
within a portable electronic device and the transmit coil may be
incorporated within a recharging device. In these embodiments, the
shielded transmit and receive coils may be positioned within their
respective housings with the open front face positioned outwardly.
In this manner, when the portable electronic device and a
recharging device are positioned nearby one another, the contoured
shields may direct flux produced by the transmit coil in the
direction of the receive coil.
[0048] FIG. 1A depicts a front perspective view of an example
inductive power transfer system in an unmated configuration. The
illustrated embodiment shows an inductive power transmitter dock
that is configured to couple to and wirelessly pass power to an
inductive power receiver accessory such as a portable electronic
device or wearable accessory.
[0049] The wearable accessory, such as depicted in FIG. 1A, may be
configured to provide health-related information or data such as
but not limited heart rate data, blood pressure data, temperature
data, oxygen level data, diet/nutrition information, medical
reminders, health-related tips or information, or other
health-related data. The wearable accessory may optionally convey
the health-related information to a separate electronic device such
as a tablet computing device, phone, personal digital assistant,
computer, and so on.
[0050] A wearable accessory may include a coupling mechanism to
connect a strap or band useful for securing to a user. For example,
a smart watch may include a band or strap to secure to a user's
wrist. In another example, a wearable health assistant may include
a strap to connect around a user's chest, or alternately, a
wearable health assistant may be adapted for use with a lanyard or
necklace. In still further examples, a wearable device may secure
to or within another part of a user's body. In these and other
embodiments, the strap, band, lanyard, or other securing mechanism
may include one or more electronic components or sensors in
wireless or wired communication with the accessory. For example,
the band secured to a smart watch may include one or more sensors,
an auxiliary battery, a camera, or any other suitable electronic
component.
[0051] In many examples, a wearable device, such as depicted in
FIG. 1A, may include a processor coupled with or in communication
with a memory, one or more communication interfaces, output devices
such as displays and speakers, and one or more input devices such
as buttons, dials, microphones, or touch-based interfaces. The
communication interface(s) can provide electronic communications
between the communications device and any external communication
network, device or platform, such as but not limited to wireless
interfaces, Bluetooth interfaces, Near Field Communication
interfaces, infrared interfaces, USB interfaces, Wi-Fi interfaces,
TCP/IP interfaces, network communications interfaces, or any
conventional communication interfaces. The wearable device may
provide information regarding time, health, statuses or externally
connected or communicating devices and/or software executing on
such devices, messages, video, operating commands, and so forth
(and may receive any of the foregoing from an external device), in
addition to communications.
[0052] Although the system 100 illustrated in FIG. 1A depicts a
wristwatch, any electronic device may be suitable to receive
inductive power from an inductive power transmitting dock. For
example, a suitable electronic device may be any portable or
semi-portable electronic device that may receive inductive power,
and a suitable dock device may be any portable or semi-portable
docking station that may wirelessly transmit inductive power.
[0053] Accordingly, the system 100 may include an inductive power
transmitter 102 and an inductive power receiver 202. The inductive
power transmitter 102 and the inductive power receiver 202 may each
respectively include a housing to enclose electronic components
therein. In many examples, and as depicted, the inductive power
receiver 202 may be larger than the inductive power transmitter
102, although such a configuration is not required.
[0054] In the illustrated embodiment, the inductive power
transmitter 102 may be connected to power, such as an alternating
current power outlet, by power cord 106. In other embodiments, the
inductive power transmitter 102 may be battery operated. In still
further examples, the inductive power transmitter 102 may include a
power cord 106 and an internal or external battery. Similarly,
although the embodiment is depicted is shown with the power cord
106 coupled to the housing of the inductive power transmitter 102,
the power cord 106 may be connected by any suitable means. For
example, the power cord 106 may be removable and may include a
connector that is sized to fit within an aperture or receptacle
opened within the housing of the inductive power transmitter
102.
[0055] As shown, the inductive power receiver 202 may include a
lower surface 208 that may interface with, align or otherwise
contact an interface surface 108 of the inductive power transmitter
102. In this manner, the inductive power receiver 202 and the
inductive power transmitter 102 may be positionable with respect to
each other. In certain embodiments, the interface surface 108 may
be configured in a particular shape that mates with a complementary
shape of the inductive power receiver 202, for example as shown in
FIG. 1B. The interface surface 108 may include a concave shape that
follows a selected curve. The bottom surface 208 of the inductive
power receiver 202 may take a convex shape following the same or
substantially similar curve as the interface surface 108. In other
examples, the interface surface 108 may be substantially flat.
[0056] Additionally or alternatively, the inductive power
transmitter and receiver devices 102, 202 can be positioned with
respect to each other using one or more alignment mechanisms. As
one example, one or more magnetic devices may be included in the
transmitter and/or receiver devices 102, 202 and may be used to
align the transmitter and receiver devices with respect to one
another. In another example, one or more actuators in the
transmitter and/or receiver devices 102 can be used to align the
transmitter and receiver devices. And in yet another example,
alignment features, such as protrusions and corresponding
indentations in the housings of the transmitter and receiver
devices, may be used to align the transmitter and receiver devices.
The design or configuration of the interface surfaces, one or more
alignment mechanisms, and one or more alignment features can be
used individually or in various combinations thereof.
[0057] FIG. 1C depicts a side cross-section view taken along line
1C-1C of FIG. 1B, showing the example inductive power transfer
system in an aligned configuration, including an example system
diagram of the inductive power receiver 202 and the inductive power
transmitter 102. As illustrated, the bottom surface 208 of the
inductive power receiver 202 contacts the interface surface of the
inductive power transmitter 102.
[0058] As described partially with respect to FIG. 1A, the
inductive power receiver 202 may include one or more electronic
components within its housing such as a processor 204 and a receive
coil 212. The receive coil 212 may have one or more windings and
may receive power from the inductive power transmitter 102.
Thereafter, the receive coil 212 may pass the received power to the
processor 204. The processor 204 may use the received power to
perform or coordinate one or more functions of the inductive power
receiver 202 and/or to replenish the charge of a battery 206.
[0059] The inductive power receiver 202 may also include other
electronic components coupled to the processor 204. For example,
the inductive power receiver 202 can include memory 210, a display
216, one or more input/output devices 218 such as buttons, force
interfaces, touch interfaces, microphones, and/or speaker(s),
communication interfaces for wired and/or wireless communication,
and so on.
[0060] The inductive power receiver 202 may also include one or
more sensors used by the processor 204 to collect environmental
information, user information, or any other type of information.
Environmental sensors may include weather sensors such as
barometric pressure sensors, humidity sensors, particle counters,
temperature sensors, moisture sensors, ultraviolet sensors,
infrared sensors, airflow and wind sensors, precipitation sensors,
accumulation sensors, and so on. User information sensors may
include health-related sensors such as skin conductance sensors,
temperature sensors, pulse oximetry sensors, blood pressure
sensors, and so on.
[0061] The inductive power transmitter 102 may also include a
transmit coil 112 having one or more windings. The transmit coil
112 may transmit power to the inductive power receiver 202. The
transmit coil 112 may be coupled to a processor 104 that may at
least partially control the transmit coil 112. For example, in
certain embodiments, the processor 104 may drive the transit coil
112 with a power signal in order to induce a particular voltage
within the receive coil 212. Both the transmit coil 112 and the
receive coil 212 may be shielded by a contoured shield 114, and 214
respectively.
[0062] The processor 104 may control or periodically adjust one or
more aspects of the power signal applied to the transmit coil 112.
For example, the processor 104 may change the operating frequency
of the power signal. In some examples, the operating frequency of
the power signal may be increased in order to increase the power
received by the receive coil 212. In addition, the processor 104
may be used to perform or coordinate other functions of the
inductive power transmitter 102.
[0063] As noted above, power transfer efficiency between the
inductive power transmitter 102 and the inductive power receiver
202 may be optimized when the receive coil 212 is aligned with the
transmit coil 112 along a mutual axis. In many examples, a slight
misalignment of the inductive power transmitter 102, for example
resulting from manufacturing variances, and the inductive power
receiver 202 may result in a substantial misalignment of the
transmit coil 112 and receive coil 212. In many examples,
misalignment may, in turn, substantially reduce power transfer
efficiency. Preferably, the inductive power transmitter 102 and the
inductive power receiver 202 are aligned along a mutual axis 300,
as shown in FIG. 1C.
[0064] FIG. 2A depicts a top perspective view of an example
unshielded transmit coil 112 that may be included in the
embodiments depicted in FIGS. 1A-1C. As illustrated, the coil 112
includes several windings of an electrical conductor such as
copper. In other embodiments, an individual winding may be composed
of several independent strands of wire. In many examples, the
windings may be provided in a substantially annular shape, with one
or more layers of windings. As depicted, three layers of four
windings provides an electromagnetic coil with twelve total turns.
In many embodiments, the leads of the coil 112 may exit the coil on
the same side. In the illustrated embodiment, the coil 112 has a
rectangular cross section, although such a configuration is not
required.
[0065] FIG. 2B and FIG. 2C depict a bottom perspective view and a
top perspective view, respectively, of the example electromagnetic
coil of FIG. 2A having a contoured shield 114 covering three sides
of the coil. As depicted, the contoured shield 114 may have three
defined surfaces. A first surface of the contoured shield 114 may
contour to the exterior sidewall of the coil 112, depicted as the
exterior perimeter of the coil 112. The first surface may be
defined by a plurality of folded petals 114a. The petals 114a may
be evenly spaced around the external perimeter of the coil 112.
[0066] A second surface of the contoured shield 114 may contour to
the interior sidewall of the coil 112. The second surface may be
defined by a plurality of folded petals 114b. As with the petals
114a, the petals 114b may be evenly spaced around the internal
sidewall of the coil 112.
[0067] A third surface of the contoured shield 114 may contour to
the back surface of the coil 112. The third surface may define a
ring 114c. In many examples, and as depicted, the petals 114a, 114b
may extend from the ring 114c, bending at an angle to contour to
the respective sidewalls of the layers of windings defining the
coil 112. In this manner, the contoured shield 114 may be formed of
a singular, unitary material. Notwithstanding, a unitary piece may
not be required or suitable for each embodiment described herein.
For example, the petals 114a, 114b may be attached or otherwise
affixed to the ring 114c by any suitable means. For example, in
certain embodiments, the petals 114a, 114b may be welded, glued, or
otherwise attached to the ring 114c in a separate manufacturing
process.
[0068] In this manner, three of four sides of the rectangular
cross-section of the coil 112 may be shielded by the shield 114. As
noted above, as a result of the contoured shield 114, magnetic flux
emanating from the interior sidewall, exterior sidewall, and back
surface of the annular transmit coil may be absorbed by the
contoured shield and redirected to exit the shield along the front
surface of the transmit coil. In other words, flux may be directed
up in relation to the orientation depicted in FIG. 2B, emanating
from the unshielded and exposed upper surface of the coil 112.
Similarly, flux may be directed down in relation to the orientation
depicted in FIG. 2C.
[0069] Although shown as separated, the petals 114a, 114b may be
joined, welded, or otherwise bonded to adjacent petals 114a, 114b
by any suitable means. In still further embodiments, the areas
between adjacent petals may be filled with a filler material. The
filler material may be a material having a high magnetic
permeability. For example, the filler material may be an adhesive
including a ferromagnetic dopant.
[0070] Although the petals 114a and 114b are illustrated as
substantially rectangular, such a configuration is not required and
other shapes are suitable to include with the various embodiments
described herein and embodiments related thereto.
[0071] In still further embodiments, the contoured shield 114 may
be formed from three separate components (i.e., outer ring, inner
ring, washer) that are welded, glued, or otherwise adhered
together.
[0072] FIG. 3A depicts an example side cross-section view taken
along line 3-3 of FIG. 2C showing the contoured shield 114 of FIG.
2C at least partially interstitially engaging an outer surface of
the coil 112. For example, a coil 112 may include more than one
stacks of windings of wire having a circular cross-section as
shown. In these embodiments, the contoured shield 114 may be formed
interstitially within the void space defined between the stacked
coils. In this manner, the contoured shield 114 may more tightly
engage the coil 112 along the ring 114c and petals 114a,114b thus
providing a path of low magnetic reluctance for the flux produced
by the coil. Accordingly, flux is directed to emanate from the
front face of the coil 112. In other words, flux may be directed
down in relation to the orientation depicted in FIG. 3A.
[0073] FIG. 3B depicts an example side cross-section view taken
along line 3-3 of FIG. 2C showing a contoured shield 114 at least
partially interstitially engaging an outer surface of the coil 112
via a heat activated film 116. As depicted, the contoured shield
114 may be affixed or adhered to the coil 112 using one or more
layers of adhesive, such as the heat activated film 116. The heat
activated film 116 adhesive may be disposed between the contoured
shield 114 and the coil 112. During a production process, the
contoured shield 114, the heat activated film 116, and the coil 112
may be heated to permanently adhere the contoured shield 114 to the
coil 112. In other embodiments, the adhesive may be a curable
liquid adhesive or any other type of adhesive.
[0074] In further embodiments, the heat activated film 116 may be
made from a polymer material that may be doped with a dopant having
high magnetic permeability. For example, the heat activated film
116 may be doped with iron powder, an iron alloy powder, or any
other high permeability dopant. In this manner, the heat activated
film 116 itself may provide a path of low magnetic reluctance for
the flux produced by the coil.
[0075] In other embodiments, the contoured shield 114 and the coil
112 may be press fit in a manufacturing process to profile an
arbitrary shape. For example, as depicted in FIG. 3C, the coil 112
and the contoured shield 114 following an upward slope. One may
appreciate that a sloping cross-section such as illustrated may
represent a cross section of a portion of a conical annular coil.
Although illustrated as following a rising slope and, by extension,
forming a conical coil, the coil 112 and contoured shield 114 may
be formed to follow any arbitrary shape. In many examples, the coil
112 and contoured shield 114 may be formed to follow a curvature of
a housing of a device, such as the inductive power receiver 202 as
shown in FIGS. 1A-1C. For example, the coil 112 and contoured
shield 114 may be formed to follow the curvature of the bottom
surface 208 as shown in FIG. 1A.
[0076] FIG. 4A depicts an example top plan view of a die cut shield
prior to forming onto an electromagnetic coil. In certain
embodiments, the contoured shield 114 may be initially formed in a
die cutting process. The die cutting process may define the
pre-contoured shape of the contoured shield 114, for example by
defining the dimensions of each of the petals 114a and 114b.
[0077] FIG. 4B depicts an example top plan view of a die cut and
separated shield prior to forming onto an electromagnetic coil. In
these embodiments, a contoured shield 114 may be electrically
separated into individual components in order to prevent or
discourage the excitation of eddy currents within the shield
material. In the illustrated embodiment, cuts may be made in the
ring 114c that separate the ring 114c and all petals 114a and
petals 114b.
[0078] FIG. 5 depicts a flow chart of example operations of a
method for applying a contoured shield to an electromagnetic coil.
The method may begin at 502 in which a sheet of material may be die
cut to form a shield. At 504, a heat activated film may be applied
to the die cut shield portion. In some embodiments the heat
activated film may be applied before the die cutting process of
502. Next at 506, the heat activated film and die cut shield may be
press fit onto the coil. In the same, or subsequent operation, each
of the petal portions may be folded around the coil. Next at 508,
heat may be applied to the assembly to activate the heat activated
film. In some embodiments, the heat may also partially melt or
soften the material selected for the die cut shield such that the
shield flows to occupy void space between individual tums of the
coil. In this manner, the shield may become interstitially
integrated with the coil.
[0079] FIG. 6 depicts a flow chart of example operations of a
method for applying a contoured shield to an electromagnetic coil.
The method may include operations similar to the method depicted in
FIG. 5. For example, the method may begin at 602 in which a sheet
of material may be die cut to form a shield. At 604, a heat
activated film may be applied to the die cut shield portion. At
606, the heat activated film and die cut shield may be press fit
onto the coil. Thereafter, at 608, heat may be applied to the
assembly to activate the heat activated film. Lastly, at 610, the
coil and shield may be press fit onto a contoured mold that may
form the coil and shield into an arbitrary shape as described above
with reference, for example, to FIG. 3C.
[0080] In the present disclosure, the methods disclosed may be
implemented as sets of instructions or software readable by a
device. Further, it is understood that the specific order or
hierarchy of steps in the methods disclosed are examples of sample
approaches. In other embodiments, the specific order or hierarchy
of steps in the method can be rearranged while remaining within the
disclosed subject matter. The accompanying method claims present
elements of the various steps in a sample order, and are not
necessarily meant to be limited to the specific order or hierarchy
presented.
[0081] The foregoing description, for purposes of explanation, used
specific nomenclature to provide a thorough understanding of the
described embodiments. However, it will be apparent to one skilled
in the art that the specific details are not required in order to
practice the described embodiments. Thus, the foregoing
descriptions of the specific embodiments described herein are
presented for purposes of illustration and description. They are
not target to be exhaustive or to limit the embodiments to the
precise forms disclosed. It will be apparent to one of ordinary
skill in the art that many modifications and variations are
possible in view of the above teachings.
* * * * *