| 摘要 |
<p>PURPOSE:To diagnose whether or not the title sensor has a defect by collating the output of a detecting element which detects the state change of an object of detection with a reference value and outputting an L or H signal, and outputting this L or H signal as a light signal of different kind. CONSTITUTION:When the object to be inspected is a door D, the sensor 1 is fixed to the door frame, etc., oppositely to a magnet 10 fitted to the door D. When the door D is closed to put the sensor 1 in the magnetic field of the magnet 10, the Hall element 2 of the sensor 1 generates an output voltage VH. When the voltage VH exceeds a reference voltage Vref set in a comparator 3, the output of the comparator 3 becomes, for example, L. Further, when the door D is opened to put the sensor 1 outside the magnetic field B of the magnet 10 and the output voltage VH of the element 2 drops below Vref, the output of the comparator 3 becomes a signal H. Then a converter 5 emits the light of a LED 4 by a signal source selected by switching the signals H and L through switches S1 and S2 having signals sources differing in frequency or phase. Thus, the absence of a signal (light emission) is detected as the defect of the sensor.</p> |
