| 摘要 |
PROBLEM TO BE SOLVED: To easily recognize presence/absence of a failure and, if a failure occurs, to repair the failure. SOLUTION: An XOR circuit 30 determines whether an output of a positive logic gate circuit 10 which selects one of logic signals A, B and an output of a negative logic gate circuit 20 which selects one of inverses A_, B_ of the signals are matched or not. If a determination result F is 1, normality can be recognized but if it is 0, a failure can be recognized. At normal time, a selector circuit 40 outputs a signal via an inverter 11 and a selector circuit 50 outputs a signal via an inverter 21. If a determination result indicates a failure, an output pattern in a case where various logic patterns are given as inputs, is analyzed to recognize whether the failure occurs in the gate circuit 10 or the gate circuit 20. If the failure occurs in the gate circuit 10, the selector circuit 40 is switched to select a signal via an inverter 22 but if the failure occurs in the gate circuit 20, the selector circuit 50 is switched to select a signal via an inverter 12. COPYRIGHT: (C)2009,JPO&INPIT
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