SENSOR DEFECTIVE DETECTING DEVICE

摘要

PURPOSE:To decrease the number of error check timers and to simplify an automatic operation system by grouping plural operation detection sensors in one and using one error detecting circuit for the group. CONSTITUTION:A timer 2 outputs a time-up signal 3 and an AND gate 21 outputs the operation defective signal of the sensor 11 unless an upper-limit operation detection sensor 11 turns on within the set time of the error check timer 2 and a bufferfly kicker enters automatic operation. When the sensor 11 outputs an on signal, the timer 2 is reset before outputting the signal 3 and outputs a downward movement signal 6 on the start of the downward movement of the bufferfly kicker to set the timer 2 and a gate 22 outputs the operation defective signal of a downward movement sensor 12 unless the sensor 12 starts operating. Thus, the system is constituted at low cost and the serviceability is improved.