| 摘要 |
PURPOSE:To make input ever so sure and simplify a device in structure as well as to prevent the occurrence of wrong operation even at the time of variations in voltage, by altering the partial pressure of a first series partial pressure resistor by operation of an operating switch to both first and second values in common with a power source, while giving these values to a comparator circuit. CONSTITUTION:Partial pressure out of first series partial pressure resistors RA-RC by operation of operating switches S11-S13 is apportioned to each line of second series partial pressure resistors R12-R14 in common with each supply voltage. And, both first and second values are given to comparators C1-C4, and the high level output is inputted into each of AND gates G1-G3. Thereupon a transistor is conducted, and each signal out of these operating switches is surely set to a flip-flop 45, then inputted into a control circuit of a valve 50. In consequence, its structure becomes relatively simple whereby each output of these comparators C1-C4 is in no case altered even if the supply voltage varies. And, even if an interval between a first series partial pressure resistance circuit 35 and these comparators C1-C4 is short- circuited, a signal equivalent to a cancel switch S13 is conducted by a second circuit, thus safety for driving is kept up.
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