US 12,451,884 B2
Inductive proximity switch and method of operation of an inductive proximity switch
Torsten Wendler, Schwarzenberg (DE)
Assigned to Turck Holdings GmbH, Halver (DE)
Filed by Turck Holding GmbH, Halver (DE)
Filed on Mar. 27, 2024, as Appl. No. 18/618,053.
Claims priority of application No. 10 2023 107 760.0 (DE), filed on Mar. 28, 2023.
Prior Publication US 2024/0333287 A1, Oct. 3, 2024
Int. Cl. H03K 17/95 (2006.01)
CPC H03K 17/9525 (2013.01) [H03K 17/9505 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An inductive proximity switch comprising:
a signal oscillating circuit and a reference oscillating circuit;
a multiplexer circuit designed to alternately activate the signal oscillating circuit and the reference oscillating circuit;
a driver circuit having an oscillator designed to operate the activated signal oscillating circuit and the activated reference oscillating circuit with an oscillator frequency, respectively;
a detection module designed to determine a number of oscillations of the activated signal oscillating circuit measured within a predetermined gate time and a number of oscillations of the activated reference oscillating circuit measured within the predetermined gate time; and
an evaluation module designed to determine a difference signal on basis of the determined number of oscillations of the activated signal oscillating circuit measured within the predetermined gate time and the determined number of oscillations of the activated reference oscillating circuit measured within the predetermined gate time, and to generate a control signal depending on the difference signal; wherein
the signal oscillating circuit is designed such that the oscillation parameter for the signal oscillating circuit depends on a position of a target in a detection zone;
the reference oscillating circuit is designed such that the oscillation parameter for the reference oscillating circuit is essentially independent of the position of the target in the detection zone;
the signal oscillating circuit includes a signal coil and the reference oscillating circuit includes a reference coil;
the reference coil has a plurality of sub-windings and the sub-windings are designed in a counter-wound manner with respect to one another; and
the reference coil has four sub-windings or a whole-number multiple of four sub-windings.