| 摘要 |
<p>PURPOSE:To detect the fault at sensitivity setting by setting the sensitivity with a comparatively simple configuration in the proximity switch. CONSTITUTION:A sensitivity adjustment circuit 21 for adjusting the sensitivity is connected to an oscillating circuit 2. Then a resistance of the sensitivity adjustment circuit 21 is sequentially increased in the oscillating state without use of a sensing object and the resistance at a position where the oscillation is stopped is sensed. In this case, a 1st fault detection means 24c senses faults when no oscillation is started with a maximum resistance. Furthermore, a 2nd fault detection means 24d senses a fault when the oscillation is not stopped with a maximum resistance. The sensitivity is set based on the resistance at the position when the oscillation is stopped when the faults are not in existence. Thus, the sensitivity is set at an optimum position without use of the sensed object.</p> |
