ELECTRONIC DEVICE HAVING AN INDUCTIVE RECEIVER COIL WITH ULTRA-THIN SHIELDING LAYER AND METHOD

• US 20150170829A1
• Filed: 02/26/2015
• Published: 06/18/2015
• Est. Priority Date: 05/20/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: WAFFENSCHMIDT, EBERHARD
• Granted Patent: US 9,795,069 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01F 2027/348 Preventing eddy currents
• CPC Class Codes: H01F 27/36 Electric or magnetic shields or screens movable for varying inductance H01F21/10
• CPC Class Codes: H01F 27/366 made of ferromagnetic material
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction
• CPC Class Codes: H05K 9/0075 Magnetic shielding materials

Abstract

An electronic device which is inductively powered or charged has a receiver coil on which a metal object can be placed without causing deterioration of the coil'"'"'s magnetic field and without generating heat in the metal object. An ultra-thin, flexible, high magnetic permeability metal foil having a thickness of 50 μm or less is provided as a shielding layer between the coil and the object. Radial slits are provided in the shielding layer, which suppress unwanted eddy currents in the layer to reduce power transfer losses and heat generation.

Claims

1. A method for configuring an electronic device for being inductively powered or charged, comprising:

configuring an inductive receiver coil for generating current in response to being exposed to an alternating magnetic field generated substantially on a first side of the inductive receiver coil; and

disposing an ultra-thin softmagnetic shielding layer on a second side of the inductive receiver coil, opposite to the first side where the magnetic field is generated, configured (i) to shield the magnetic field from an overlying object wherein the overlying object is (i)(a) subject to being undesireably influenced by the magnetic field, or (i)(b) subject to causing an undesireable influence on the magnetic field and (ii) to mitigate formation of eddy currents within the shielding layer and the overlying object, wherein the shielding layer comprises a thickness less than or equal to one hundred micrometers (100 μ

m).

2. The method of claim 1, wherein disposing said shielding layer includes providing at least one eddy current mitigation feature that comprises a number of slits formed within the shielding layer, wherein the slits are substantially parallel to magnetic flux lines and orthogonal to eddy current flow for imposing a large impedance to eddy current formation.

3. The method of claim 2, wherein the slits formed within the softmagnetic shielding layer are created via laser cutting, wherein a layer of softmagnetic shielding material is attached to a transparent adhesive foil, laser energy is directed towards the softmagnetic shielding material layer at desired sites to evaporate corresponding softmagnetic shielding material to form the slits, wherein the transparent adhesive foil remains intact.

4. The method of claim 1, wherein a total thickness of the inductive receiver coil and the ultra-thin softmagnetic shielding layer is on the order of less than 300 μ

m, and wherein the ultra-thin softmagnetic shielding layer comprises a material selected from the group consisting of Mumetal, nanocristaline metal and amorphous metals.

5. The method of claim 1, wherein the overlying object comprises one selected from the group consisting of (i) a rechargeable battery with a conductive housing, (ii) an electronic circuit and (iii) a lamp module with a metallic base plate, further wherein the metallic base plate of the lamp module is configured for being disposed overlying the shielding layer, the lamp for being powered in response to the generated current.