Sense coil geometries with improved sensitivity for metallic object detection in a predetermined space

A method for detecting a presence of an object, the method comprising:

• determining a measured value of an electrical characteristic of a sense coil that varies as a function of the presence of the object, the 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
• detecting the presence of the object in response to detecting a difference between the measured value of the electrical characteristic and a reference value for the electrical characteristic.

An apparatus for detecting a presence of an object, the apparatus comprising:

• a sense coil having an outer loop and an inner loop defined by a conductor that crosses itself at a transition between the outer loop and the inner loop 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.

A method for detecting a presence of an object, the method comprising:

• determining a measured value of an electrical characteristic of a sense coil that varies as a function of the presence of the object, the sense coil having an outer loop and an inner loop defined by a conductor that crosses itself at a transition between the outer loop and the inner loop, and
• detecting the presence of the object in response to detecting a difference between the measured value of the electrical characteristic and a reference value for the electrical characteristic.