Patent ID: 6859140

Claim:
A proximity or presence switch arrangement operating in accordance with the inductive principle, comprising at least one inductor integrated in an oscillating circuit and an electronic control and evaluation device connected downstream for sensing or detecting the approach and/or presence of a material influencing electromagnetic fields, characterised in that the oscillating circuit ( 2 ) is excited at predetermined time intervals to generate an independently excited, the excitation signal having a frequency which is equal to or different from the inherent oscillation frequency of the oscillating circuit ( 2 ), in that the electronic device ( 3 ) detects and evaluates the change(s) in one or more parameter(s) and triggers or causes (a) corresponding action(s) if the evaluation results exceed predetermined thresholds, and in that the excitation signal is a periodic pulse signal and in that the independently excited oscillation signal generated has an at least slight amplitude which decays with time, the cycle of the pulse signal being at least five times greater than the cycle of the oscillation generated.