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`(19) United States
`
`
`(12) Patent Application Publication
`(10) Pub. No.: US 2005/0189910 Al
`
`Sep. 1, 2005
`Hui
`( 43) Pub. Date:
`
`US 20050189910Al
`
`(54) PLANAR INDUCTIVE BATTERY CHARGER
`
`
`
`(76) Inventor: Shu-yuen Ron Hui, Hong Kong (HK)
`
`Nov. 18, 2002
`(GB) ......................................... 0226893.6
`
`Mar. 10, 2003
`
`(GB) ......................................... 0305428.5
`
`Publication Classification
`
`Correspondence Address:
`
`HESLIN ROTHENBERG FARLEY & MESITI
`PC
`5 COLUMBIA CIRCLE
`ALBANY, NY 12203 (US)
`
`(51) Int. Cl.7 ........................................................ H02J 7/00
`
`
`(52) U.S. Cl. .............................................................. 320/108
`
`(57)
`
`ABSTRACT
`
`11/009,478
`(21) Appl. No.:
`
`Dec. 10, 2004
`(22) Filed:
`
`There is provided a planar inductive battery charging system
`
`
`
`
`
`
`
`
`
`designed to enable electronic devices to be recharged. The
`
`
`
`
`system includes a planar charging module having a charging
`
`
`
`
`surface on which a device to be recharged is placed. Within
`
`
`
`
`the charging module and parallel to the charging surface is
`
`
`
`
`
`at least one and preferably an array of primary windings that
`(63) Continuation of application No. PCT/AU03/00721,
`
`
`
`
`
`
`
`couple energy inductively to a secondary winding formed in
`
`filed on Jun. 10, 2003.
`
`
`the device to be recharged. The invention also provides
`
`
`
`secondary modules that allow the system to be used with
`
`
`conventional electronic devices not formed with secondary
`windings.
`Jun. 10, 2002
`
`(GB) ......................................... 0213374.2
`
`Related U.S. Application Data
`
`(30) Foreign Application Priority Data
`
`2
`
`1
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 001
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 1 of 32
`
`US 2005/0189910 Al
`
`charger
`
`FIG.I (PRIOR ART)
`
`Magnetic
`core for
`pnmary
`winding
`
`Primary
`winding
`
`FIG.2 (PRIOR ART)
`
`Air gap
`
`Magnetic
`core for
`secondary
`winding
`
`Secondary
`winding
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 002
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 2 of 32
`
`US 2005/0189910 Al
`
`Copper Sheet
`
`__,,...,.,__Thennally Cqnductive
`
`
`Insulating Layer
`� L Polyurethane-coated
`J Insulated Copper Wires
`
`
`Dielectric Laminate
`
`�rimary Winding
`
`Ferrite Plate
`
`...____ Copper Sheet
`
`FIG.3 (PRIOR ART)
`
`2
`
`1
`
`FIG.4(a)
`
`FIG.4(b)
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 003
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 3 of 32
`
`US 2005/0189910 Al
`
`◄
`
`◄
`
`◄
`
`.◄
`
`4
`
`5
`
`6
`
`7
`
`FIG.4(c)
`
`FIG.5(a)
`
`FIG.5(b)
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 004
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 4 of 32
`
`US 2005/0189910 Al
`
`FIG.6(a)
`
`120
`
`115
`
`110
`
`105
`
`100
`
`9S
`
`90
`
`90
`
`80
`0
`
`Y(mm)
`
`FIG.6(b)
`
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`•• 20 • 40 60 80 100 120
`
`X{mm)
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 005
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 5 of 32
`
`US 2005/0189910 Al
`
`FIG.7(a)
`
`Magnetic
`fh,1x
`magnitude
`
`distance
`
`FIG.7(b)
`
`FIG.8
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 006
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 6 of 32
`
`US 2005/0189910 Al
`
`FIG.9{a)
`
`140
`
`130
`
`;;- 120
`
`110
`
`·a
`)1
`
`100
`
`90
`
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`130
`
`125
`
`120
`
`11S
`
`110
`
`105
`
`LOO
`
`95
`
`90
`
`FIG.9(b)
`
`120
`
`85
`
`X(mm)
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 007
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 7 of 32
`
`US 2005/0189910 Al
`
`FIG.IO(a)
`
`.
`
`.
`
`.
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`· B
`
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`
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`
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`
`FIG.lO(b)
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 008
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 8 of 32
`
`US 2005/0189910 Al
`
`Energy coupled zones
`
`A
`
`rectifier
`
`Battery load
`
`Secondary
`winding
`
`B
`
`C
`
`D
`
`Groups of
`primary windings
`
`High­
`frequency
`AC voltage
`source
`
`FIG.IO(c)
`
`�---11--1------ . secondary charger
`
`Integrated
`
`system
`
`FIG.11
`
`s for
`Mechanical contact
`
`
`
`connection with the battery pack
`.,.
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 009
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 9 of 32
`
`US 2005/0189910 Al
`
`FIG.12(a)
`
`14
`
`FIG.12(b)
`
`FIG.12(c)
`
`10
`11
`12
`
`11
`
`�12
`
`13
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 010
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 10 of 32
`
`US 2005/0189910 Al
`
`10
`
`11
`
`12
`
`25
`
`FIG.12(d)
`
`FIG.13(a)
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 011
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 11 of 32
`
`US 2005/0189910 Al
`
`25
`
`24
`
`23
`
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`
`20
`
`FIG.13(b)
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 012
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 12 of 32
`
`US 2005/0189910 Al
`
`31
`
`32
`
`30
`
`FIG.14
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 013
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 13 of 32
`
`US 2005/0189910 Al
`
`•••••
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`FIG.16
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 014
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 14 of 32
`
`US 2005/0189910 Al
`
`FIG.17
`
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`□□□□□
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`
`FIG.18
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 015
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 15 of 32
`
`US 2005/0189910 Al
`
`----------,r
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`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 016
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 16 of 32
`
`US 2005/0189910 Al
`
`
`
`Magnetic field magnitude distribution in the first layer
`
`
`
`
`
`Magnetic field magnitude distribution in the second layer
`
`Distance
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`
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`
`FIG.21
`
`FIG.22
`
`FIG.23
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 017
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 17 of 32
`
`US 2005/0189910 Al
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 018
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 18 of 32
`
`US 2005/0189910 Al
`
`mmf
`
`1
`
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`
`0- +- ----___,;:I._-L _____ �_
`
`FIG.25
`
`FIG.26
`
`p
`
`p
`
`p
`
`FIG.27
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 019
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 19 of 32
`
`US 2005/0189910 Al
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`. ..
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`Momentum Dynamics Corporation
`Exhibit 1011
`Page 020
`
`

`

`Patent Application Publication
`
`Sep. 1, 2005 Sheet 20 of 32
`
`US 2005/0189910 Al
`
`..
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`Momentum Dynamics Corporation
`Exhibit 1011
`Page 021
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 21 of 32
`
`US 2005/0189910 Al
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`. . ··-...
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`Momentum Dynamics Corporation
`Exhibit 1011
`Page 022
`
`

`

`Patent Application Publication
`
`Sep. 1, 2005 Sheet 22 of 32
`
`US 2005/0189910 Al
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`Momentum Dynamics Corporation
`Exhibit 1011
`Page 023
`
`

`

`Patent Application Publication
`
`Sep. 1, 2005 Sheet 23 of 32
`
`US 2005/0189910 Al
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`.. . . ..
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`Momentum Dynamics Corporation
`Exhibit 1011
`Page 024
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 24 of 32
`
`US 2005/0189910 Al
`
`Tnmj
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`
`FIG.34
`
`FIG.35
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 025
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 25 of 32
`
`US 2005/0189910 Al
`
`□□□□□4------1
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`
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`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 026
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 26 of 32
`
`US 2005/0189910 Al
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`la []
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`Momentum Dynamics Corporation
`Exhibit 1011
`Page 027
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 27 of 32
`
`US 2005/0189910 Al
`
`FIG.39
`
`FIG.40
`
`- ffi-
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 028
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 28 of 32
`
`US 2005/0189910 Al
`
`109
`
`102
`
`FIG.41
`
`FIG.42
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 029
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 29 of 32
`
`US 2005/0189910 Al
`
`106
`
`FIG.43
`
`107
`
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`
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`
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`
`FIG.44(b)
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`
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`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 030
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 30 of 32
`
`US 2005/0189910 Al
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`�
`
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`
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`
`FIG.47
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`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 031
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 31 of 32
`
`US 2005/0189910 Al
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`FIG.49
`
`FIG.50
`
`202
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 032
`
`

`

`Patent Application Publication Sep. 1, 2005 Sheet 32 of 32
`
`US 2005/0189910 Al
`
`FIG.SI
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 033
`
`

`

`US 2005/0189910 Al
`
`Sep. 1,2005
`
`1
`
`
`
`FIELD OF THE INVENTION
`
`primary winding being substantially parallel to said planar
`PLANAR INDUCTIVE BATTERY CHARGER
`charging surface, wherein said primary winding is provided
`with electromagnetic shielding on the side of said winding­
`opposite from said planar charging surface, and wherein said
`electronic device is formed with a secondary winding.
`
`[0001] This invention relates to a battery charger, and in
`particular to a battery charger having a planar surface on
`which one or more battery powered devices may be placed
`for battery recharging through induction. The invention also
`extends to a battery charging system for use with conven­
`tional electronic devices and that allows conventional elec­
`tronic devices to be charged using the battery charging
`system of the present invention.
`
`BACKGROUND OF THE INVENTION
`
`[0002] Portable electronic equipment such as mobile
`phones, handheld computers, personal data assistants, and
`devices such as a wireless computer mouse, are normally
`powered by batteries. In many cases, rechargeable batteries
`are preferred because of environmental and economical
`concerns. The most common way to charge rechargeable
`batteries is to use a conventional charger, which normally
`consists of an AC-DC power supply (in case of using the ac
`mains) or a DC-DC power supply (in case of using a car
`battery). Conventional chargers normally use a cord (an
`electric cable for a physical electrical connection) to connect
`the charger circuit ( a power supply) to the battery located in
`the portable electronic equipment. The basic schematic of
`the conventional battery charger is shown in FIG. 1.
`[0003]
`Inductive electronic chargers without direct physi­
`cal electrical connection have been developed in some
`portable electronic equipment such as electric toothbrushes
`where because they are designed to be used in the bathroom
`in the vicinity of sinks and water, it is not safe to provide a
`conventional electrical connection. Various known inductive
`type chargers, however, use traditional transformer designs
`with windings wound around ferrite magnetic cores as
`shown in FIG. 2. The main magnetic flux between the
`
`primary winding and secondary winding has to go through
`the magnetic core materials. Other contactless chargers
`proposed also use magnetic cores as the main structure for
`the coupled transformer windings.
`
`[0004] A contactless charger using a single primary
`printed winding without any EMI shielding has been pro­
`posed for portable telecommunications/computing electron­
`ics. However, the magnetic flux distribution of a single spiral
`winding has a major problem of non-uniform magnetic flux
`distribution. As illustrated further below, the magnitude of
`the magnetic field in the center of the core of a spiral
`winding is highest and decreases from the center. This
`means that if the portable electronic device is not placed
`properly in the central region, the charging effect is not
`effective in this non-uniform field distribution. Furthermore,
`without proper EMI shielding, undesirable induced currents
`may flow in other metallic parts of the portable electronic
`equipment.
`
`SUMMARY OF THE INVENTION
`
`[0005] According to the present invention there is pro­
`vided a battery charger system comprising a charging mod­
`ule comprising a primary charging circuit and being formed
`with a planar charging surface adapted to receive an elec­
`tronic device to be charged, wherein said primary charging
`circuit includes a primary winding of a transformer, said
`
`In a preferred embodiment the primary winding is
`[0006]
`formed on a planar printed circuit board.
`
`[0007] Preferably the magnetic flux generated by the pri­
`mary winding is substantially uniform over at least a major
`part of the planar charging surface. In this way the precise
`position and orientation of the electronic device on the
`charging surface is not critical. To achieve this the charging
`module may comprise a plurality of primary windings,
`which may preferably be disposed in a regular array.
`
`In a preferred embodiment the primary winding is
`[0008]
`provided with electromagnetic shielding on the side of said
`winding opposite from said planar charging surface. This
`shielding may include a sheet of ferrite material, and more
`preferably also may further include a sheet of conductive
`material such as copper or aluminium
`
`It is an advantage of the present invention that in
`[0009]
`preferred embodiments the planar charging surface may be
`large enough to receive two or more electronic devices, and
`the primary charging circuit is adapted to charge two or
`more devices simultaneously. In this way it is possible to
`charge more than one device simultaneously. For example
`the planar charging surface may be divided into a plurality
`of charging regions, which regions may be defined by
`providing a plurality of primary transformer windings
`arranged in a regular array and connecting the windings in
`groups to define said charging regions. A further advantage
`of the present invention is that it enables the possibility of
`allowing a device to move over the charging surface while
`being charged at the same time. This possibility is particu­
`larly useful to a device which is designed to be moved such
`as a wireless computer mouse
`
`[0010] Viewed from another aspect the present invention
`provides a battery charging system comprising a charging
`module comprising a primary charging circuit and being
`formed with a charging surface for receiving an electronic
`device to be charged, wherein said charging module com­
`prises a plurality of transformer primary windings arranged
`in a regular array.
`
`In addition to the battery charging system, the
`[0011]
`invention also extends to a battery powered portable elec­
`tronic device comprising a rechargeable battery, and wherein
`the device includes a planar secondary winding for receiving
`electrical energy from a battery charger, and electromagnetic
`shielding between the winding and the major electronic
`components of said device.
`
`[0012] Preferably, the shielding comprises a sheet of fer­
`rite material and a sheet of conductive material such as
`copper.
`
`[0013] Preferably the winding is formed integrally with a
`back cover of said device.
`
`[0014] An important aspect of the present invention is that
`it provides a battery charging system that employs a loca­
`lised charging concept. In particular, when there is an array
`of primary coils, it will be understood that energy is only
`transferred from those primary coils that are adjacent the
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 034
`
`

`

`US 2005/0189910 Al
`
`Sep. 1,2005
`
`2
`
`secondary coil located in the device being charged. In other
`words, when a device is placed on a planar charging surface
`that is greater in size than the device, energy is only
`transferred from that part of the planar charging surface that
`is directly beneath the device, and possibly also immediately
`adjacent areas that are still able to couple to the secondary
`coil.
`
`[0015] Viewed from another aspect the present invention
`provides a battery charging system comprising a primary
`module and at least one secondary module, said primary
`module comprising means for connecting to a mains supply,
`and at least one primary winding adjacent to a charging
`surface of said primary module, and wherein said secondary
`module comprises a secondary winding adjacent to a surface
`of said secondary module, circuit means for converting
`alternating current generated in said secondary winding to a
`regulated DC output, and a charging connector for connec­
`tion to the charging socket of an electronic device.
`
`[0016] According to another aspect the invention also
`extends to a secondary module for a battery charging sys­
`tem, comprising: a housing having at least one charging
`surface, a winding provided in said housing adjacent to said
`surface and adapted to receive magnetic flux when said
`surface is brought adjacent to a primary winding, circuit
`means for converting alternating current in said secondary
`winding to a regulated DC output, and a connector means for
`connecting said DC output to the charging socket of an
`electronic device.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0017] Some embodiments of the invention will now be
`described by way of example and with reference to the
`accompanying drawings, in which:
`
`[0018] FIG. 1 is a schematic view of a conventional prior
`art battery charger with direct electrical connection,
`
`[0019] FIG. 2 is a schematic view of a conventional
`magnetic core-based transformer as used in prior art induc­
`tive battery charger systems,
`
`[0020] FIG. 3 is a schematic view of a planar transformer
`with shielding,
`
`[0021] FIGS. 4(a)-(c) are (a) a perspective view of a
`battery charger system according to an embodiment of the
`present invention, (b) a view similar to (a) but showing the
`structure of the primary charging system, and (c) a view
`similar to (a) and (b) but showing the top cover removed for
`clarity,
`
`[0022] FIGS. 5(a) & (b) show the structure of the primary
`charger with the top cover removed for clarity, and in FIG.
`5(a) with the structure shown in exploded view,
`
`[0023] FIGS. 6(a) & (b) show (a) a single spiral PCB
`winding, and (b) the measured magnetic field distribution of
`a single spiral winding,
`
`[0024] FIGS. 7(a) & (b) illustrate the use of a magnetic
`core to control magnetic field distribution,
`
`[0026] FIGS. 9(a) & (b) shows (a) a 4x4 primary winding
`array, and (b) the resulting magnetic field distribution,
`
`[0027] FIGS. lO(a)-(c) illustrate an embodiment of the
`invention in which primary windings are arranged in groups
`with FIG. lO(c) showing the equivalent circuit,
`
`[0028] FIG. 11 shows an example of the back cover of an
`electronic device designed to be recharged using an embodi­
`ment of the present invention,
`
`[0029] FIGS. 12(a)-(d) show exploded views of the back
`cover of FIG. 11,
`
`[0030] FIGS. 13(a) & (b) show views of a watch that may
`be recharged in accordance with an embodiment of the
`invention,
`
`[0031] FIG. 14 shows a charging module in accordance
`with an alternative embodiment of the invention,
`
`[0032] FIG. 15 shows a first layer of a 4x5 winding array
`for use in a multi-layer embodiment,
`
`[0033] FIG. 16 shows a second layer of a 3x4 winding
`array for use in conjunction with the layer of FIG. 15 in a
`multi-layer embodiment,
`
`[0034] FIG. 17 shows the layers of FIG. 15 and FIG. 16
`in the two-layer structure,
`
`[0035] FIG. 18 is simplified version of FIG. 15,
`
`[0036] FIG. 19 is a simplified version of FIG. 16,
`
`[0037] FIG. 20 is a simplified version of FIG. 17,
`
`[0038] FIG. 21 is a plot showing the smoothing effect of
`the two-layer structure,
`
`[0039] FIG. 22 shows a hexagonal spiral winding,
`
`[0040] FIG. 23 is a simplified form of FIG. 22,
`
`[0041] FIG. 24 shows a single-layer of hexagonal spiral
`windings,
`
`[0042] FIG. 25 shows two adjacent hexagonal spiral
`windings,
`
`[0043] FIG. 26 shows the mmf distribution of the adjacent
`windings of FIG. 25,
`
`[0044] FIG. 27 shows three adjacent hexagonal spiral
`windings and the peaks and minima of the flux distribution,
`
`[0045] FIG. 28 shows two overlapped layers of hexagonal
`spiral windings,
`
`[0046] FIG. 29 shows the location of the peak flux in the
`structure of FIG. 28,
`
`[0047] FIG. 30 corresponds to FIG. 29 but also shows the
`location of the flux minima,
`
`[0048] FIG. 31 shows an embodiment of the invention
`formed with three overlapped layers,
`
`[0049] FIG. 32 corresponds to FIG. 31 but shows the
`location of the flux peaks,
`
`[0050] FIG. 33 is a plot showing the uniformity of the flux
`distribution along a line,
`
`[0025] FIG. 8 shows an embodiment of the invention in
`which a plurality of primary windings are arranged in an
`array structure,
`
`[0051] FIG. 34 shows a square spiral winding,
`
`[0052] FIG. 35 is a simplified version of FIG. 34,
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 035
`
`

`

`US 2005/0189910 Al
`
`Sep. 1,2005
`
`3
`
`[0053] FIG. 36 shows a first layer of square spiral wind­
`ings,
`
`[0054] FIG. 37 corresponds to FIG. 36 but shows the
`location of the flux maxima and minima,
`
`[0055] FIG. 38 shows two overlapped layers of square
`spiral windings including the location of the flux maxima
`and minima,
`
`[0056] FIG. 39 shows three overlapped layers of square
`spiral windings including the location of the flux maxima
`and minima,
`
`[0057] FIG. 40 shows four overlapped layers of square
`spiral windings including the location of the flux maxima
`and minima,
`
`[0058] FIG. 41 illustrates a battery charging system
`according to a further embodiment of the invention,
`
`[0059] FIG. 42 is a view similar to FIG. 41 but part
`broken away to show the primary winding,
`
`[0060] FIG. 43 is a view similar to FIG. 42 but of an
`alternate embodiment,
`
`[0061] FIGS. 44(a) and (b) illustrate possible magnetic
`cores for use in the embodiment of FIG. 42,
`
`[0062] FIG. 45 shows an equivalent circuit for the charg­
`ing system of an embodiment of the invention,
`
`[0063] FIG. 46 illustrates an example of a secondary
`module for use in an embodiment of the invention,
`
`[0064] FIG. 47 shows a part broken away view of sec­
`ondary module of an embodiment of the invention,.
`
`[0065] FIG. 48 is a view similar to FIG. 47 but of a further
`embodiment,
`
`[0066] FIG. 49 is a view showing the complete charging
`system according to an embodiment of the invention,
`
`[0067] FIG. 50 is a view similar to FIG. 49 but showing
`how the charging system according to an embodiment of the
`invention can be used to charge multiple devices having
`different forms of charging connections, and
`
`[0068] FIG. 51 is a view illustrating how an embodiment
`of the present invention can be used to enable a conventional
`electronic device to be charged using an inductive charging
`platform as shown in FIG. 4.
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`[0069] The present invention will now be described in
`respect of a preferred embodiment in the form of an induc­
`tive battery charger for portable electronic equipment such
`as mobile phones, handheld computers and personal digital
`assistants (PDA), and devices such as a wireless computer
`mouse.
`
`[0070] Referring firstly to FIG. 4, the inductive charger
`system comprises two modules, a power delivering charger
`module that contains the primary circuit of a planar isolation
`transformer and a secondary circuit that is located in the
`portable electronic equipment to be charged. In this embodi­
`ment of the invention, the charger circuit is located within a
`housing 1 that is formed with a flat charging surface 2. The
`secondary circuit is formed in the portable equipment to be
`
`charged (in this example a mobile phone 3) and the equip­
`ment is formed with at least one planar surface. As will be
`seen from the following description the equipment is
`charged simply by placing the equipment on the surface so
`that the planar surface on the equipment is brought into
`contact with the flat charging surface 2. It is a particularly
`preferred aspect of the present invention that the equipment
`to be charged does not have to be positioned on the charging
`surface in any special orientation. Furthermore, in preferred
`embodiments of the invention two or more mobile devices
`may be charged simultaneously on the same charging sur­
`face, and/or a device that is designed to be moved (such as
`a wireless computer mouse) can be charged while being
`moved over the charging surface (which could be integrated
`into a computer mouse pad). It will also be seen from the
`following description that the energy transfer is "localised"
`in the sense that energy is only transferred from the charging
`surface to the device from that part of the charging surface
`that is directly beneath the device (and possibly to a lesser
`extent regions adjacent thereto).
`
`[0071] Referring in particular to FIG. 4(b) the primary
`charging module comprises a printed circuit board 4 formed
`with at least one spiral conductive track formed thereon as
`a primary winding. It will be understood, however, that the
`primary winding need not necessarily be formed on a PCB
`and could be formed separately. Alternatively, multiple
`PCBs each formed with at least one winding could be
`"stacked" on top of each other to increase the total flux.
`Preferably, as will be described further below, there are in
`fact a plurality of such spiral tracks disposed in an array as
`shown in FIG. 4(c) in which a top insulating sheet has been
`removed for clarity. Beneath the PCB 4 (ie the side of the
`PCB away from the charging surface) is provided EMI
`shielding comprising firstly a ferrite sheet 5 adjacent the
`PCB 4, and then a conductive sheet 6 which in this example
`may be a copper sheet. Beneath the copper sheet 6 may be
`provided any suitable form of substrate material 7, eg a
`plastics material. Above the PCB 4 may be provided a sheet
`of insulating material 8 which forms the charging surface.
`Preferably the PCB 4, the EMI shielding sheets 5,6, the
`substrate 7 and the insulating cover sheet 8 may also be
`generally the same size and shape, for example rectangular,
`so as to form the primary charging module with the charging
`surface being large enough to accommodate at least one, and
`more preferably two or more, devices to be charged. FIGS.
`5(a) and (b) also show the structure of the charging module
`without the cover sheet and without any devices to be
`charged thereon for the sake of clarity.
`
`[0072] As shown in FIG. 4, the primary transformer
`circuit module transmits electrical energy at high frequency
`through a flat charging surface that contains the primary
`transformer windings. The secondary winding is also planar
`and is located in the portable electronic equipment and
`couples this energy, and a rectifier within the portable
`equipment rectifies the high-frequency secondary AC volt­
`age into a DC voltage for charging the battery inside the
`portable equipment either directly or via a charging circuit.
`The rectified DC voltage is applied to the battery via
`mechanical contacts provided in an integrated back cover as
`will be described further below. No physical electrical
`connection between the primary charger circuit and the
`portable electronic equipment is needed.
`
`Momentum Dynamics Corporation
`Exhibit 1011
`Page 036
`
`

`

`US 2005/0189910 Al
`
`Sep. 1,2005
`
`4
`
`[0073] The primary charger circuit has (1) a switched
`mode power electronic circuit, (2) the primary side of a
`planar transformer that consists of a group of primary
`windings connected in series or in parallel or a combination
`of both, (3) an EMI shield and ( 4) a flat interface surface on
`which one or more portable electronic devices can be placed
`and charged simultaneously. The schematic of the primary
`charger system is shown in FIG. 5(a) and (b) without the
`insulating cover.
`
`[0074] The battery charging system can be powered by AC
`or DC power sources. If the power supply is the AC mains,
`the switched mode power electronic circuit should perform
`a low-frequency (50 or 60 Hz) AC to DC power conversion
`and then DC to high-frequency (typically in the range from
`20 kHz to 10 MHz) AC power conversion. This high­
`frequency AC voltage will feed the primary planar windings
`of the primary charger circuit. If the power supply is a
`battery ( e.g. a car battery), the switched mode power supply
`should perform a DC to high-frequency AC power conver­
`sion. The high-frequency voltage is fed to the primary
`windings of the planar transformer.
`
`[0075] Preferably, the charger should be able to charge one
`or more than one items of portable electronic equipment at
`the same time. In order to achieve such a function, the AC
`magnetic flux experienced by each item of portable equip­
`ment placed on the charging surface should be as even as
`possible. A standard planar spiral winding as shown in FIG.
`6(a) is not suitable to meet this requirement because its flux
`distribution is not uniform as shown in FIG. 6(b) when the
`winding is excited by an AC power source. The reason for
`such non-uniform magnetic flux distribution is that the
`number of turns in the central region of the single spiral
`winding is largest. As the magnitude of the magnetic flux
`and the magnetomotive force (mmf) is proportional to the
`product of the number of turn and the current in the winding,
`the magnetic flux is highest in the centre of the winding.
`
`[0076] One method to ensure uniform magnetic flux or
`mmf distribution is to use a concentric primary winding with
`a planar magnetic core as shown in FIG. 7(a). This magnetic
`core-based approach allows the magnetic flux to concentrate
`inside the core and typical magnetic flux distribution is
`shown in FIG. 7(b). In general, the flat charging interface
`surface of the primary charger should be larger than the total
`area of the portable electronic equipment.
`
`In order to ensure that more than one item of
`[0077]
`portable electronic equipment can be placed on the flat
`charging surface and charged simultaneously, a second and
`more preferred method proposed is to ensure that the mag­
`netic flux distribution ex