| 摘要 |
PURPOSE:To check easily and accurately the operation of the operation state display circuit by ORing an operating voltage and a check voltage exclusively and controlling dichroic light emitting elements. CONSTITUTION:A low-level check voltage from a terminal 4 and an operation state voltage from a terminal 5 which is at a high level normally and at a low level in alarm mode are processed by an exclusive OR circuit 21, which generates a high- or low-level output according to whether the operation is normal or not. Then, a light emitting element 2 for one color in normal operation or a light emitting element 3 for the other color in abnormal operation is turned on through an inverting circuit 22 and a double inverting circuit 23. Namely, the high-level check voltage is applied to the terminal in order to check the operation, and then the element 2 or 3 which is on in either normal or abnormal operation turns off and the other element 3 or 2 turns on. Thus, the operation of the operation state display circuit is checked easily and accurately.
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