| 摘要 |
<p>PURPOSE:To enable easy checkup of functions of a differential-type detecting device by providing a generating unit of radiation energy at one position whereat distances from a pair of differential-type detecting elements are different from each other. CONSTITUTION:Detecting elements 4 and 5 are operated to monitor a prescribed monitoring area. Generating units 7 and 8 are driven to check up whether the detecting elements 4 and 5 operate or not. When radiation energy is generated alternately from the two generating units 7 and 8 by operations of switching means 9 and 10, the radiation energy received by the two detecting elements 4 and 5 varies in a large degree. Accordingly, there occurs large unbalance in the radiation energy received by the two detecting elements 4 and 5, and a composite output of the two detecting elements 4 and 5 is not 0 but turns to be a prescribed positive or negative output if there is no fault. By checking up this output, functions of a detecting device 1 as a whole can be checked up easily.</p> |
