| 摘要 |
The invention relates to an inductive proximity switch which has a resonant circuit (Ls, C) comprising a resonant circuit transmission coil (Ls) and a capacitance (C), wherein the resonant circuit transmission coil (Ls) generates an alternating magnetic field which induces a mutual induction voltage in at least one receiving coil (LE), and the oscillation state of the resonant circuit can be influenced by means of a metallic release which enters or moves away from the alternating field. An evaluation circuit is used to obtain a switching signal (uswitch) from the change in the oscillation state of the resonant circuit, wherein the change in the complex coupling between the at least two coils, the transmission coil (Ls) and the receiving coil (LE), can be evaluated, as a switching signal (uswitch), using an auxiliary voltage signal (UHSP) in the presence or absence of the release. The auxiliary voltage signal (UHSP) is obtained in a predefinable ratio (v) as a partial voltage from the resonant circuit voltage (USK) of the resonant circuit (Ls, C), wherein the auxiliary voltage signal (UHSP) is connected in series with the mutual induction voltage induced in the receiving coil (LE) in such a manner that a differential voltage (UD) whose magnitude has been reduced in comparison with the induced mutual induction voltage by the auxiliary voltage signal (UHSP) is obtained at the output of the receiving coil (LE), to earth (G) or to a potential. The differential voltage (UD) is supplied to the evaluation circuit (DG, SK) in a suitable manner in order to obtain the switching signal (Uswitch). The proximity switch may also be in the form of an oscillator.
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