Patent ID: 7463020

Claim:
An inductive proximity switch based on the transformer coupling-factor principle, having at least one transmitting coil, one oscillator circuit and at least two receiving coils arranged in the alternating magnetic field of the transmitting coil, whereby the transmitting coil and the receiving coil are arranged adjacent to each other on a printed circuit board, and also having an evaluation circuit connected to the receiving coils, whereby, when a target approaches the proximity switch, said evaluation circuit generates a switching signal on the basis of the evaluation of the received signals of the receiving coils, characterized in that the at least two receiving coils (E 1 , E 2 , Bi, En, 7 , 8 , 12 , 13 ) and the transmitting coil (S, S A , 11 ) are each made up of at least one annular or elliptical or polygonal or spiral winding and each delineate a circular or annular or polygonal or elliptical coil surface area, whereby the transmitting coil (S, 11 ) is peripherally surrounded by the first receiving coil (E 1 , 12 ) which is, in turn, peripherally surrounded by the second receiving coil (E 2 , 13 ) or the first receiving coil ( 7 ) is surrounded by the second receiving coil ( 8 ) which is, in turn, peripherally surrounded by the transmitting coil (S A ); in the case of a perpendicular parallel projection onto the coils, the coil surface area spanned by the outer-most coil in each case completely covers the coil surface areas of all of the other coils and the coil surface area spanned by the innermost coil is completely covered by the coil surface areas of all of the other coils, and moreover, in a perpendicular parallel projection onto the coils, the transmitting coil (S, 11 , S A ) is at a distance from its adjacent receiving coil (E 1 , E 2 , 12 , 13 , En) without the projections of the coils overlapping.