| 摘要 |
A proximity sensor includes an L-C resonator, an oscillator for oscillating the L-C resonator, an oscillation detector, an output circuit, and a burnout detecting means. The L-C resonator has a detection coil for detecting an object, and a resonant capacitor connected across the detection coil. The oscillation detector detects an oscillation of the L-C resonator. The burnout detecting means has a time counter for counting a length of a positive voltage period in which a voltage across the resonant capacitor is kept above a predetermined positive voltage, and a discriminator which determines burnout of the detection coil when the counted length exceeds a half of an oscillation cycle of the L-C resonator. The output circuit outputs a detection signal indicative of whether or not the object exists within a detection range of the detection coil, and provides a burnout signal indicative of the burnout of the detection coil. |
