Inductive Proximity Switch Based on a Transformer Coupling Factor Principle

摘要

The invention relates to a preferably ferriteless inductive proximity switch 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 coil for evaluating the received signal of the receiving coils when a target approaches the proximity switch. The receiving coils (E 1 , E 2 , Ei, En, 7, 8, 12, 13 ) as well as the transmitting coil (S, S_A, 11 ) are made up of at least one polygonal or annular or elliptical winding and they each delineate a polygonal or annular or elliptical coil surface area, whereby either the transmitting coil (S, 11 ) is surrounded by a first receiving coil (E 1, 12 ) which is, in turn, surrounded by a second receiving coil (E 2, 13 ) and optionally, said second receiving coil is surrounded by a third or n^th peripheral receiving coil (En), or a first receiving coil ( 7 ) is surrounded by the second receiving coil and optionally, said second receiving coil is surrounded by a third or n^th receiving coil, whereby the n^th receiving coil is peripherally surrounded by the transmitting coil (S_A), so that in both alternatives, the coil surface area spanned by the outermost coil in each case completely covers all of the coil surface areas of the other coils situated further towards the inside and moreover, in a perpendicular parallel projection onto the coils, the transmitting coil (S, 11 , S_A) is at a distance from its closest adjacent receiving coil (E 1 , E 2, 12, 13 , En) without the transmitting coils and/or the receiving coils overlapping.