Inductive proximity switch and method for its operation
AssigneePepperl + Fuchs GmbH
InventorThomas Kuehn
Life of this patent
Estimating the term…
Abstract
The present invention relates to an inductive proximity switch with an oscillator having a resonant circuit and an amplifier and with an evaluating and control device for evaluating an impedance of the resonant circuit and for outputting a switching signal. According to the invention, the proximity switch is characterized in that a frequency measuring device is provided for measuring the oscillation frequency of the oscillator and for eliminating ambiguities of the evaluation result of the evaluating and control device. The invention also relates to a method for operating an inductive proximity switch.
Claims16
Inductive proximity switch, comprising:
- an oscillator with a resonant circuit and an oscillator amplifier,
- an evaluating and control device for evaluating an impedance (Z) of the resonant circuit and for outputting a switching signal, and
- a frequency measuring device for measuring an oscillation frequency of the oscillator and for eliminating ambiguities of an evaluation result of the evaluating and control device with respect to whether a target is a ferrous or a non-ferrous target
- wherein the oscillator amplifier can be set to at least two different gains.
Method for operating an inductive proximity switch comprising:
- evaluating an impedance (Z) of a resonant circuit of an oscillator as a measure for a range of a target, the oscillator including a resonant circuit and an oscillator amplifier,
- comparing the impedance (Z) of the resonant circuit with at least one threshold to obtain and output a switching signal, and
- measuring the frequency of the oscillator in order to eliminate ambiguities of an evaluation result of the impedance (Z) of the resonant circuit with respect to whether a target is a ferrous or a non-ferrous target;
- wherein the oscillator amplifier can be set to at least two different gains.
Dependencies are inferred from the claim text.