Selectively controllable electromagnetic shielding

摘要

A selectively controllable electromagnetic shield having an electromagnetic shielding material and a mechanism for selectively generating an aperture in the shield. The mechanism for selectively generating an aperture may be a magnetic field source that generates a magnetic field of sufficient strength to substantially saturate all or a portion of the shielding material. For example, a permanent magnet or DC electromagnet may be used to selectively saturate the shield. In its un-saturated state, the magnetic shield has a high permeability and functions as a flux path for the magnetic field. Once saturated, the permeability of the shield is substantially reduced so that the magnetic field lines are no longer drawn into the shield to the same degree. As a result, once saturated, a substantially greater amount of the electromagnetic field may flow through or around the shield in the saturated region.

主权项

1. An electromagnetic shielding system for selectively shielding and allowing transmission of wireless power, said electromagnetic shielding system comprising:
a wireless power supply having an electromagnetic field transmitter for generating an electromagnetic field, said electromagnetic field transmitter being disposed in proximity to a power transfer surface; a remote device separate from and positionable on said power transfer surface, said remote device having an electromagnetic field receiver capable of receiving wireless power from said electromagnetic field transmitter via said electromagnetic field; an electromagnetic shield adjacent to or forming at least a portion of said power transfer surface, said electromagnetic shield preselected to have a permeability substantially greater than a permeability of ambient space such that said electromagnetic shield when unsaturated provides an electromagnetic flow path of lesser resistance than ambient space, whereby the unsaturated electromagnetic shield shields said electromagnetic field from transferring wireless power via said electromagnetic field to said electromagnetic field receiver; and a magnetic field source carried by said remote device, said magnetic field source being separate from the electromagnetic field transmitter and positioned or positionable proximate said electromagnetic shield, said magnetic field source being preselected to generate a magnetic field of sufficient strength such that, in response to generation of said magnetic field in proximity to said electromagnetic shield, at least a portion of said electromagnetic shield substantially saturates where it is desirable to allow the electromagnetic field to pass from said electromagnetic field transmitter to said electromagnetic field receiver, thereby selectively reducing said permeability of said electromagnetic shield such that said electromagnetic shield no longer provides an electromagnetic flow path of lesser resistance than ambient space, whereby said magnetic field source is used to selectively saturate the electromagnetic shield when it is desirable to allow the electromagnetic field to pass from the electromagnetic field transmitter to the electromagnetic field receiver to transfer wireless power thereto, whereby removal of said magnetic field allows said at least a portion of said electromagnetic shield to become unsaturated.