SENSE COIL GEOMETRIES WITH IMPROVED SENSITIVITY FOR METALLIC OBJECT DETECTION IN A PREDETERMINED SPACE

摘要

This disclosure provides systems, methods and apparatus for detecting a presence of an object. In one aspect an apparatus for detecting a presence of an object is provided. The apparatus includes a sense coil formed from a conductor having a predetermined shape configured to attenuate currents induced in the conductor by an external time-varying magnetic field. The sense coil has an electrical characteristic that varies as a function of the presence of the object. The apparatus comprises a detection circuit coupled to the sense coil and configured to detect the presence of the object in response to detecting a difference between a measured value of the electrical characteristic and a reference value for the electrical characteristic. The reference value for the electrical characteristic is substantially the same as the measured value of the electrical characteristic in the absence of the object over at least a portion of the sense coil.

主权项

1. An apparatus for detecting a presence of an object, the apparatus comprising:
a sense coil having a plurality of sides defined by a conductor, wherein for each of the plurality of sides of the sense coil, the conductor bows toward a center of the sense coil as the conductor extends from an outer portion of the respective side of the sense coil toward a middle portion of the respective side of the sense coil, and wherein the sense coil has an electrical characteristic that varies as a function of the presence of the object; and a detection circuit coupled to the sense coil and configured to detect the presence of the object in response to detecting a difference between a measured value of the electrical characteristic and a reference value for the electrical characteristic.