| 摘要 |
PROBLEM TO BE SOLVED: To simplify constitution and to facilitate manufacture inspection by comparing the voltage level of the DC components of signals with a prescribed voltage range and recognizing the operation condition of a microcomputer. SOLUTION: The safety pulse output 7 of the microcomputer 1 is smoothed in a CR circuit and converted into a DC level signal 19 as the voltage level signal of the DC components proportional to the pulse duty of safety pulse output signals. The DC level signal 19 is compared with a reference potential in comparators 17 and 18 and power is supplied to a driving circuit power source 8 only when it is in the prescribed voltage range. The output of the comparator 17 becomes High output at the time of the DC level signal 19<Vh (upper limit voltage) and the output of the comparator 18 becomes High output at the time of the DC level signal 19>V1 (lower limit voltage). Thus, the output of the comparators 17 and 18 becomes active and the power is supplied to the driving circuit power source 8 only at the time of being in the voltage range of the V1 < the DC level signal 19<Vh and the driving circuit power source 8 is interrupted at the time of the DC level signal 19<V1 or Vh < the DC level signal 19.
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