| 摘要 |
PURPOSE:To easily obtain a proximity switch with high speed operation and high stability, by giving a bias voltage with a prescribed frequency and amplitude to a parallel resonance circuit consisting of a detecting coil and a capacitor and giving a prescribed amplitude for the oscillation start condition after a body to be detected is parted. CONSTITUTION:An oscillation circuit 1 including a parallel resonance circuit consisting of a detection coil 4 and a capacitor 5 and an amplitude comparison circuit 2 are provided. To this parallel resonance circuit, a bias voltage with a prescribed frequency and amplitude is given, and an detected output of a body to be detected of a proximity switch circuit is given to the base of a transistor TR6 and the collector of a TR9 from a parallel resonance circuit. An AC voltage source 12 is connected in series with the parallel resonance circuit, and a negative conductance is connected in parallel with the series circuit. Thus, according to the oscillated amplitude of the circuit 1, the circuit 2 generates an output signal. Thus, the oscillation start condition after the parting of the body to be detected can be made with a prescribed amplitude. |
