| 摘要 |
1. A device for detecting a magnetic target (7) in a proximity zone comprising a well-defined external limit (14) comprising an inductive sensor (3) having a resonant LC circuit in which the approach of the target causes a variation in the phase displacement between the current and the voltage in the resonant circuit, and an oscillator (1) emitting a voltage signal at stable frequency, characterised in that the resonant circuit is a series circuit and in that the detecting device also comprises an electronic board (11) remote from the sensor (3), comprising the oscillator (1) of which the signal is sinusoidal, of constant amplitude and within the low frequency range, a line control circuit (2) supplied by the oscillator (1) and supplying the sensor (3), a circuit (4) for detecting the passage through zero of the voltage supplied by the oscillator (1), a circuit (5) for detecting the passage through zero of the current supplied by the line control circuit (2), and a phase comparing circuit (6) of which the output changes state when phase displacement between the current and the voltage changes sign, signifying that the target (7) has reached the external limit (14) of the proximity zone. |
