Patent ID: 7759939

Claim:
A sensor for locating metallic objects, in particular a metal sensor for building materials, having at least one transmission coil ( 116 , 216 ) for inducing a flux and at least one reception conductor loop system ( 112 , 212 ) for receiving said flux modified by a metallic object, wherein said at least one transmission coil ( 116 , 216 ) and said at least one reception conductor loop system ( 112 , 212 ) are inductively coupled to one another, wherein the reception conductor loop system ( 112 , 212 ) is comprised of conductor structures on a printed circuit board ( 100 , 200 ), wherein a second reception conductor loop system ( 114 , 214 ) is provided for receiving said flux, wherein said second reception conductor loop system ( 114 , 214 ) is situated coaxial to the first reception conductor loop system ( 112 , 212 ), in a common first plane ( 126 , 226 ) with it on the printed circuit board ( 100 , 200 ), so that a presence of a metallic object is determined when changes in inductive properties caused by the metallic object are registered by said first and second reception conductor loop systems, and wherein the sensor operates in a frequency range between 1 kHz and 10 kHz.