| 摘要 |
PURPOSE:To provide a highly reliable logic operation circuit with high fail safety performance capable of judging both decision by majority and the fault of circuit by letting a binary input signal be a binary signal which is not mistaken as a logic value '1', adding it and converting it into a multilevel signal which is not mistaken on the side with the higher addition value. CONSTITUTION:The output end of a voltage doubler rectifier circuit 23 is connected to the earth terminal of a voltage doubler rectifier circuit 22. The output end of the circuit 22 is successively stacked up and connected toward the earth terminal of the circuit 21. The output voltages Va, Vb, and Vc of diodes D21-D23 for clamp use of the respective circuits 21 to 23 are added and obtained on an output terminal (a). A majority decision circuit 5 produces the output of decision by majority when two inputs or more are at the high level from among inputs given from A to C systems. A monitoring circuit 6, if one of logic operation oscillators 11-13 and rectifier circuits 21-23 has a fault in circuit, the level of the output end (a) can not keep Vc+Vb+Va, resulting in losing the monitoring output. In short, the fail safety performance can be secured for the fault of circuit. |
