Metal layer for inductive power transfer

An electronic device for receiving inductive power transfer from an inductive charger using an alternating magnetic field at an operating frequency, the electronic device comprising:

• an inductive charging receiver comprising:
• a substantially planar inductive charging receiver coil positioned substantially parallel to a bottom surface of the electronic device that faces the inductive charger for inductive power transfer;
• and
• an electrically conductive shield layer comprising metal,
• wherein the shield layer is positioned proximate to the inductive charging receiver coil to cover a surface of the inductive charging receiver coil,
• wherein the shield layer comprises multiple substantially concentric metallic rings, with each of the metallic rings comprising multiple sections,
• wherein radially adjacent sections of the metallic rings are electrically isolated from one another, and
• wherein the sections of each of the metallic rings are separated by gaps such that each metallic ring is electrically discontinuous to impede eddy current generation in the metallic rings and the shield layer and to impede heating of the shield layer by the alternating magnetic field during inductive power transfer.

An inductive charging system that uses an alternating magnetic field for inductive power transfer, the inductive charging system comprising:

• a substantially planar inductive coil;
• a substantially planar shielding means for reducing electromagnetic interference or heat distribution from the inductive coil during inductive power transfer,
• wherein the shielding means is positioned proximate to and substantially parallel to the inductive coil to cover a surface of the inductive coil,
• wherein the shielding means comprises electrically conductive metal;
• wherein the shielding means comprises multiple substantially concentric metallic rings, with each of the metallic rings comprising multiple sections,
• wherein radially adjacent sections of the metallic rings are electrically isolated from one another, and
• wherein the sections of each of the metallic rings are separated by gaps such that each metallic ring is electrically discontinuous to impede eddy current generation in the metallic rings and the shielding means and to impede heating of the shielding means by the alternating magnetic field during inductive power transfer.

An inductive charging system that uses an alternating magnetic field for inductive power transfer, the inductive charging system comprising:

• an inductive coil having an annular spiral shape with an inner radius that is 5/16 or more of an outer radius;
• a shielding means for reducing electromagnetic interference or heat distribution from the inductive coil during inductive power transfer, wherein the shielding means is positioned proximate to the inductive coil to cover a surface of the inductive coil,
• wherein the shielding means comprises electrically conductive metal having a thickness of 100 micrometers or less, and
• wherein the shielding means includes radially arranged electrical gaps to impede eddy current generation in the shielding means and to impede heating of the shielding means by the alternating magnetic field during inductive power transfer.