| 摘要 |
PURPOSE:To obtain a field type detector which can detect the defect of the detector itself, by changing applied electromagnetic waves accompanied with a change of the electrostatic capacity to report the disconnection and the short-circuit of a conductor, which detects the approach of a person, through a detection line connected to this conductor. CONSTITUTION:When the electrostatic capacity between a conductor 1 and the earth becomes large because of the approach of a person, the combined impedance becomes small, and the amplitude of electromagnetic waves which have the voltage divided by an oscillating circuit 4 and capacitors 3 and 5 becomes small. Then, the output of a wave detecting circuit 8 is lowered, and the output level of a BPF 9 becomes large, and a reporting circuit 2 is operated by a discriminating circuit 10. Meanwhile, when the conductor 1 is disconnected. The output of a photocoupler, which is formed with a phototransistor 19 and an LED 15 connected to a DC power source 16 of a disconnection detecting circuit 22, is inverted to the high level through a detection line 11 connected to the conductor 1, and the circuit 2 is operated through a comparator 21. Similarly, when the conductor is short-circuited, the continuity of a change of electromagnetic waves for a prescribed time or more is detected by a short-circuit detecting circuit 23 provided in an integral network 25, and a reporting equipment 2 is operated, thus obtaining a field type detector which can detect the defect of itself. |
