FAIL-SAFE MAJORITY LOGIC CIRCUIT AND PARALLEL OUTPUT TYPE ELECTRONIC INTERLOCKING DEVICE USING THIS CIRCUIT

摘要

PROBLEM TO BE SOLVED: To find a single fault in the early stage and to prevent erroneous output to the dangerous side even at the time of the occurrence of the signal fault. ;SOLUTION: In the fail-safe majority logic circuit for majority decision of at least three logical inputs, every two inputs of three inputs are put together by three OR circuits 311, and outputs of these OR circuits 311 are put together by a 3-input AND circuit 321. This control is provided with the control mode and the fault detection mode; and in the fault detection mode, a pattern for fault detection is inputted and the output is observed to detect a fault of parts constituting the circuit. If a fault is detected, the input is forcedly changed so that the circuit doesn't output the output to the dangerous side. This fail-safe majority logic circuit is applied to an electronic interlocking device to improve the safety of this device.;COPYRIGHT: (C)1997,JPO