Inductive proximity detector safety device controlling a mechanical member

The device delivers an electric safety signal which only allows a dangerous movement on a machine under the sole and unique condition that the mechanical member which it controls is definitely in a position making it possible to carry out the movement without danger. The safety inductive proximity detector comprises a high frequency oscillator (1), a rectifier amplifier (4), actuated by an object fitted with an active part comprising an inductor (10) and a multivibrator (12). This object simulates, in the vicinity of the detector, alternately, and at a certain frequency, the presence and absence of a metal object within the sensitive volume of the detector (1 to 8). Its inductor (10) placed in the HF field of the detector supplies the multivibrator and is periodically shortcircuited by the latter, thus simulating the presences and absences. The inductive proximity detector translates, at its output (9) these alternate presences and absences into a succession of electric voltage squareways, these squareways constituting the safety signal. A device makes use of this signal and only supplies an electric current under the sole and unique condition of receiving the safety signal.