| 摘要 |
PURPOSE:To secure fail-safe by providing a delay circuit and a logical circuit and stopping a microprocessor by means of continuous light abnormality which occurs in a short time. CONSTITUTION:The delay circuit 1 delays a reset signal (a) for a fixed set time. When the light abnormality detection signal (e) of the microprocessor, which is detected in an abnormality detection circuit 7, can be obtained within the time which is set in the delay circuit 1, it is assumed to be the occurrence of light abnormality which is not accidental in the microprocessor since the output signal (d) of FF3 is turned off. The AND of the inverse signal of the output signal (d) from FF3 and the light abnormality detection signal (e) is taken in an AND gate 6b, and the stop signal (f) of the microprocessor is outputted to the output terminal. Thus, the microprocessor can be stopped and the safe operation of the microprocessor can be secured. |
