Circuit for detecting door state in copying apparatus

摘要

A level shift circuit for indicating the open or closed condition of an access door of a copier senses the powered condition of operating portions of the copier to which the supply of power is interrupted when the access door is open and provides a corresponding logic signal to a sequence control circuit of the copier. In the disclosed embodiment, a series-connected resistor and zener diode are connected to the copier operating portions to provide an output signal through an inverting buffer to the sequence control circuit.